AE-106

Purdue University

Cooperative Extension Service

West Lafayette, IN 47907



FAN SIZING AND APPLICATION FOR BIN DRYING/COOLING OF GRAIN



Bruce A. McKenzie and George H. Foster,
Extension Agricultural Engineers, Purdue University
Sherwood S. DeForest, P.E.
Agricultural Engineer, Consultant


Contents



Introduction   
                                        
Air Flow System Performance and Energy Relationships
  Grain depth vs. fuel efficiency
  Grain depth vs. air flow
  Air flow resistance vs. air velocity
  Grain depth vs. static pressure
  Static pressure vs. fan type

Fan Performance Data                                  
  Packing factor
  Fan efficiency
  Determining specific fan performance
  Air flow guidelines

Using the Bin Drying Performance Tables                 

Dryeration and Bin Cooling Performance Table and Guidelines
  Using the performance table
  Estimating required horsepower and surface area

Plotting Air Flow System Performance                    

Factors Affecting Fan Performance                       
  Drying capacity vs. grain depth
  Fines and air flow uniformity
  Unusual fan horsepower ratings

Bin Drying Air Flow Rate Performance Tables             

Crop-Fan-Match Computer Program Input Form          

The sizing and application of fans are important in determining how much time is needed to dry and cool grain, what these jobs will cost and, in the final analysis, how much energy you will use. The less time involved in drying and cooling, the less your energy requirement will be. This, of course, will be reflected in a lower dollar cost for fan operation.

This publication presents data and tables for determining the air flow, system performance and energy relationships in bin drying and cooling. This will help you (1) to select the fan(s) for your particular application, and (2) through the use of example problems, to calculate the type and size of fans needed for your own grain facility.

From the information presented here, you should be able to answer such questions as:

The data presented cover fans that range in air flow delivery capacity from 0.33 to 10.0 or more cubic feet per minute per bushel (cfm/bu.) for drying and cooling shelled yellow corn and soybeans. The data are applicable to fans for (1) dryeration or simple cooling, using air flow rates in the range of 0.5 to 1.0 cfm/bu., and (2) bin drying systems normally operating in the range of 1.0 to 10.0 cfm/bu. (No data are included for the air flow range normally used in aeration--typically 0.1 to 0.5 cfm/bu. for farm installations--and as low as 1/50th cfm/bu. for some elevator facilities.)

AIR FLOW, SYSTEM PERFORMANCE AND ENERGY RELATIONSHIPS

It is important to understand the relationship between grain depth and air flow resistance, velocity and static pressure conditions that occur in a bin. These relationships, in turn, have a marked effect on proper drying performance. If we understand the principles that make for efficient grain drying, we can best select the proper fan needed for operation--and thus conserve energy.

Grain Depth vs. Fuel Efficiency

A common error in operating bin dryers is to place too much grain in the bin. This is especially true in bin drying procedures that use partial fills but can occur in full-bin drying also.

All bin drying processes are energy efficient for bed depths 2 1/2 feet and above, in terms of using the heat applied to the drying air. Fuel efficiency does not change much as the bed depth increases above the minimum, but air flow efficiency does. Proper fan selection and application are prime contributors to overall dryer efficiency.

Grain Depth vs. Air flow

A common misconception among users of bin dryers is that air flow resistance through a bed of grain is independent of air velocity. Indeed it is not. Consider this: If you have 1000 bushels of grain to dry, there is a very great difference between drying it "1000 bushels wide and one bushel deep" and drying it "one bushel wide and 1000 bushels deep!"

The wider and thinner grain can be spread out, the less fan capacity-required to dry it in a given period of time. This principle is illustrated in Figure 1. The column of grain in the center of the bin has a cross-sectional area of exactly 1.25 square feet (sq. ft.). Each foot of column height contains one bushel (one bushel equals 1.25 cubic feet).

Figure 1. Grain bin cross section with a 1.25 square foot area grain "chimney" filled to 12-, 16- and 20-foot depths. Each foot of grain column contains one bushel. At an air flow rate of 2 cfm/bu., required air velocity for grain is 24 cfm at the 12-foot depth, 32 cfm at 16 feet and 40 cfm at 20 feet.

Assume that an air flow rate of 2 cfm/bu. is applied to the bin, flowing upward through the column of grain. A 12-foot depth, then, requires 24 cfm (2 cfm/bu. x 12 bu.). The air flow entering the column has a velocity of 24 cfm/1.25 sq. ft. of floor area or 19.2 feet per minute (fpm).

Adding 4 feet of grain and maintaining the same 2 cfm/bu. air flow level requires a velocity of 25.6 fpm (32 cfm ÷ 1.25 sq. ft.). Adding another 4 feet of grain and maintaining the same 2 cfm/bu. air flow level requires 32 fpm (40 cfm ÷ 1.25 sq. ft.).

These grain depth/air flow relationships and their effect on horsepower are seen in Table 1. The table shows the fan horsepower required to deliver air flow through 10-, 12-, 16- and 20-foot depths of grain in a 30-foot diameter grain bin.

Table 1 Air Flow Rates for Various Depths in a 30-Foot Diameter Bin

		Power needed to deliver air flow thru grain depth of--
Air flow    -------------------------------------------------------------
  rate       10 feet          12 feet         16 feet           20 feet 
--------------------------------------------------------------------------
cfm/bu

1.0            ---             2.5 hp          6.7 hp           14.2 hp
2.0            7.1 hp         13.2 hp         36.2 hp           80.6 hp
         (16.0 cfm.sq ft) (19.2 cfm/sq ft)  (25.6 cfm/sq ft) (32.0 cfm/sq ft)
3.0            ---            36.8 hp        103.5 hp            ----
------------------------------------------------------------------------------

Note how much the horsepower has to increase to sustain a 2 cfm/bu. air flow delivery as the grain depth increases. Doubling the depth from 10 to 20 feet requires over 10 times more horsepower! Also notice that holding the grain depth constant at 16 feet and doubling the air flow from 1 to 2 cfm/bu. increases the fan horsepower required by more than 5 times,

In neither case does the bin diameter or amount of open space between the kernels change. But in both cases, the air flow rate per square foot or bin floor area doubles. This means the air velocity has to double.

These relationships suggest two rules of thumb for sizing fans for drying systems: (1) doubling the grain depth at the same cfm/bu. air flow rate requires 10 times more horsepower; and (2) doubling the cfm/bu. air flow rate on the same depth of grain requires 5 times more horsepower.

Air Flow Resistance vs. Air Velocity

Resistance to air flow is closely related to air bvelocity. Air flow resistance increases exponentially (increases at an increasing rate) as velocity increases. Doubling fan size from 10 to 20 horsepower (hp), for example, does not double the air volume. To double the air volume, the power must be increased from 10 to over 50 hp!

It makes little difference what brand or type of fan you use within the range of correct application for that fan. Although there are small differences in the performance of competing manufacturers' fans of the same general horsepower and size, their overall performance will be similar to the generalized data included in this publication.

Grain Depth vs. Static Pressure

Static pressure is the force required to overcome the resistance to air flow through grain and is usually expressed in inches of water column. It is also the measure used to rate a fan's performance under load conditions such as drying, cooling and aerating grain.

Static pressure is measured with a simple instrument known as a manometer (Figure 2), which is connected to the air plenum of a grain bin (air space below the false floor). An operating fan creates a pressure in the plenum great enough to push air up through the grain. This pressure also pushes on the open end of the manometer tube, causing the fluid in the manometer to move down one leg of the U-shaped tube and up the other. The difference in the level of the two columns (measured in inches of water) is the static pressure supplied by the fan.

Figure 2. A simple manometer connected to a section of grain bin. To measure static pressure (non-moving, no-velocity air), the opening at the end of the manometer tube that extends into the bin plenum must be at a right angle to the moving air; the other end is open to the atmosphere. On a frame with a scale calibrated in inches, the tube is `U' shaped and partly filled with fluid (sometimes colored for easier reading). In this figure, the difference in the fluid level between the two columns of the `U' is 2 inches, meaning the fan is operating under 2 inches of static pressure (water column).

The easier the air moves through the grain, the lower the static pressure. Thus, as a grain bin is filled with the fan "on," air flow is restricted and the static pressure increases. Increasing the air flow rate for a given depth of grain will increase the static pressure rapidly.

This relationship of static pressure and grain depth is presented graphically in Figure 3. To use the graph, follow the 16-foot depth line from the bottom of the graph, projecting upward to intersect the 1 and 2 cfm/bu. curves. Project these intercepts across to the static pressure scale on the left side of the graph. You will read approximately 2.4 and 6.4 inches of water column static pressure.

Figure 3. Grain depth vs. static pressure at selected air flow rates for bin drying shelled corn and soybeans.

As you see, static pressure nearly triples when the air flow doubles. Pressure values for other combinations of fill depths and air flow levels can be estimated similarly.

Static Pressure vs. Fan Type

Table 2 compares typical air performance data for a vane-axial fan and a centrifugal fan, each with a 10 hp motor. Air flow capabilities of the two types of fan differ significantly above and below the equal-performance point, which is about 4.0-4.5 inches of static pressure.

Table 2. Typical Fan Data for a 10-hp Vane Axial Fan and a 10-hp Centrifugal Fan.


                                        Air flow at static pressures of--
Type of      fan     ------------------------------------------------------------------------------               
 fan       diameter  1.0"   1.5"    2.0"   2.5"    3.0"    3.5"    4.0"    4.5"  5.0"   5.5"  6.0"
---------------------------------------------------------------------------------------------------
            inches                             cubic feet per minute

Vane axial    28   19,000  18,100 17,000  16,200  14,900  13,800  12,700   --   9,400   --      --
Centrifugal   24   13,200    __   12,700   --     12,100   --     11,300   --   9,000   --    8,500
-----------------------------------------------------------------------------------------------------

Vane-axial fans (Figure 4a) supply more cfm per horsepower at static pressures below 4.0-4.5 inches of water than centrifugal units. For this reason, these fans are generally better adapted to shallow-depth bin drying systems, such as batch-in-bin and continuous-in-bin systems, and to deep bin drying up to 20-foot depths requiring 1 cfm/bu. air flow or less. They are generally lower in initial cost, but operate at a higher noise level than centrifugal fans.

Centrifugal fans (Figure 4b) supply more cfm per horsepower at static pressures above 4.0-4.5 inches of water than vane-axial fans. They are especially advantageous when the application requires relatively high air volumes through deep grain levels (12-20 feet), and where low noise is important.

Figure 4. Basic fan types for bin drying/cooling. (a) The vane-axial type has a propeller and vanes, and is best for static pressures under 4.0-4.5 inches of water. (b) The centrifugal type generally supplies more cfm per horsepower at static pressures over 4.0-4.5 inches of water and is often used where low noise level is desired.

FAN PERFORMANCE DATA

The tables and charts in this publication can help you estimate fan performance for bin drying or cooling. The data, although based on shelled yellow-dent corn, are also generally applicable to soybeans. Fan performance is based on a packing factor of 1.5 times that of clean shelled corn and an installed fan efficiency typical of commercial fans.

Packing Factor

Packing factor is an index or ratio of the air flow resistance of a given grain depth to the resistance of the same grain when cleaned and piled in a loose fill. Loose fill occurs when grain is introduced into a bin at nearly zero velocity (without dropping), flowing into a cone-shaped pile. The descending grain then rolls or slides slowly down the coned grain surface.

In contrast, the grain in your bins usually has greater resistance to air flow than loose-fill grain. This is because it contains `fines,' is often dropped some distance onto the pile or is thrown by a distributor to the grain surface. As grain is distributed from above onto a surface of accumulated grain, the impact of the dropping, skipping kernels agitates the surface of the grain already in place. This agitation tends to orient the grain kernels into tightly-compacted positions, and causes fines to sift into the open spaces between kernels. The result is a "compacted fill."

The amount and the distribution of fines in grain for drying or aeration are very important. A high level of fines sharply increases the grain resistance to air flow. And the uneven distribution of fines prevents uniform air flow through various sections of the grain mass.

A packing factor is usually applied to grain in designing air flow systems in order to compensate for normal packed fill, fines deposit and air duct losses. A packing factor of 1.5 is a good design value for shelled corn and assumes a 50 percent increase in overall air flow resistance compared to loose fill.

Fan Efficiency

Fan efficiency for crop-drying and aeration fans will typically range from a high of 55-60 percent down to 40 percent. The installed efficiency depends on: (1) the quality of the fan and (2) the static pressure of the load in relation to the fan's performance curve. If the load very nearly matches the high performance range of the fan's output curve, the installed fan efficiency will be high. Conversely, if the fan output curve and load characteristics match poorly, the installed fan performance may be low.

The fan performance data in this publication are based on fan curves for each horsepower size, derived by averaging the data from a number of commercial fans. These fans, when applied correctly, will normally operate in an efficiency range of 50-60 percent.

Air Flow Guidelines

In selecting or evaluating fans for grain drying and bin cooling systems, the guidelines in Table 3 may be used.

Table 3. Recommended Air Flow Rates for Bin Cooling and Drying.


                         Rate max. and min. or    Recommended
       System            grain moisture level    air flow rate
 ------------------------------------------------------------------
  Dryeration & bin cooling   Minimum                0.5  cfm/bu.
                             Good design            0.75 cfm/bu.
                             Maximum                1.0  cfm/bu.
------------------------------------------------------------------
 Deep bed bin drying*
      Corn                 20-22%  moisture          1.0 cfm/bu.
                           22-24%  moisture          2.0 cfm/bu.
                           24-26%  moisture          3.0 cfm/bu.
----------------------------------------------------------------
      Soybeans                17%  moisture          1.0 cfm/bu.
                              19%  moisture          2.0 cfm/bu.
                              21%  moisture          3.0 cfm/bu.
-------------------------------------------------------------------
  * 12-16 feet deep preferred, 20 feet maximum recommended.

The air flow rates listed for dryeration and bin cooling are adequate. But the question is, how fast do you wish to cool the grain? At 0.5 cfm/bu. air flow rate, the cooling time will be roughly 10-15 hours of fan operation. A 1.0 cfm/bu. rate will cut this time roughly in half-to 6-8 hours.

Dryeration air flow rates should not exceed the maximum recommended design level of 1.0 cfm/bu. to avoid exhausting the warm air from the corn before it can pick up a full load of moisture. The air flow rate is not critical during bin cooling if there is no heat-soak or tempering period prior to cooling. But grain that is bin-cooled immediately (with the higher air flow rates used for bin drying) could suffer a reduction in quality.

The air flow rates listed for corn and soybean drying are only for deep-bed bin drying systems. Partial-fill systems using batch-in-bin or continuous-in-bin methods run at much higher air flow and drying rates.

USING THE BIN DRYING PERFORMANCE TABLES

This publication provides air flow rate performance tables for bin drying with selected tan sizes and grain depths in bins 14, 18, 21, 24, 27, 30, 33, 36, 40, 42 and 48 feet in diameter (Tables 6-16). For purposes of illustration here, Table 4 (repeated later as Table 11) presents the performance data for a 30-foot bin.

In the table, grain depth and corresponding bushel volume are shown across the top of the columns, while fan horsepower is arranged down the left-most column. The data in the body of the table are air flow rates in cfm/bu. All grain fills are assumed to be level (not peaked).

Now, let's apply this example table to several typical, practical situations:

How do I choose fan horsepower for an existing or new bin?

Assume that you wish to dry 16 feet of shelled corn in a 30-foot diameter bin at a 1.5 cfm/bu. air flow rate. Enter Table 4 at the 16-foot depth heading at the top of the chart. Follow down the air flow values until you find one of at least 1.5 cfm/bu. (1.55 cfm/bu.). Then move left to the first column and read the required horsepower (15).

Table 4. Air Flow Rates at Various Fan Sizes and Grain Depths for Drying Shelled Corn and Soybeans in a 30-Foot Diameter Bin (Average commercial fan performance and 1.5 packing factor).*



              Air flow rate needed for a grain depth (and corresponding bushel volume) of--
        ----------------------------------------------------------------------------------------
 Fan    2 ft.   4 ft.  6 ft.  8 ft.  10 ft.  12 ft. 14 ft. 16 ft.  18 ft.  20 ft.  22 ft.   24 ft.
 hp    (1131)  (2262) (3393) (4524)  (5655)  (6786) (7917) (9048)  (10179) (11310) (12441)  (13572)
--------------------------------------------------------------------------------------------------
                                  cfm/bushel **

0.33    1.38    .68    .45    .34    .27     .22    .19     .16     .14     .13     .12      .11
0.5     1.80    .89    .59    .44    .35     .29    .25     .21     .19     .17     .15      .14
0.75    1.94    .97    .64    .48    .38     .32    .27     .24     .21     .19     .17      .16

1.0     2.58   1.29    .85    .64    .51     .42    .36     .31     .28     .25     .22      .20
1.5     3.75   1.86   1.23    .92    .73     .60    .51     .44     .39     .35     .31      .28
2.0     4.58   2.25   1.48   1.09    .86     .70    .60     .51     .45     .40     .36      .32

3.0     5.83   2.89   1.90   1.41   1.11     .92    .77     .66     .58     .51     .45      .41
4.0     7.31   3.62   2.37   1.74   1.36    1.10    .92     .78     .68     .59     .53      .47
5.0     9.43   4.63   3.00   2.18   1.69    1.36   1.13     .96     .83     .72     .64      .57

7.5    11.39   5.54   3.57   2.58   1.99    1.60   1.33    1.12     .97     .85     .75      .66
10.0   13.51   6.58   4.23   3.02   2.32    1.86   1.53    1.28    1.10     .96     .84      .75
12.5   15.43   7.37   4.71   3.36   2.56    2.04   1.67    1.39    1.19    1.04     .92      .81

15.0   19.76   9.18   5.64   3.92   2.93    2.30   1.86    1.55    1.32    1.14     .99      .88
20.0   22.46  10.20   6.25   4.30   3.18    2.46   1.99    1.65    1.39    1.20    1.05      .93
25.0   25.93  11.31   6.77   4.66   3.44    2.65   2.12    1.76    1.49    1.27    1.10      .97
										----------------	
30.0   29.53  12.66   7.45   5.02   3.68    2.86   2.28    1.87    1.57    1.34 | 1.18      1.06
					                ------------------------
40.0   33.00  13.78   7.97   5.33   3.89    2.99   2.38 |  2.04    1.63    1.56   1.39      1.25
50.0   39.39  15.57   8.92   5.87   4.26    3.27   2.58 |  2.21    1.92    1.70   1.52      1.36
--------------------------------------------------------------------------------------------------
   * Fan performance based on an average of a number of commercial
fans for each hp.  Packing factor assumes 1.5 x Shedd's data for
clean, loose-filled grain (10.0). See reference section for source
details.

   **Cfm values below stepped line are centrifugal fans; above line
are van axial designs.  Change normally occurs between 4 and 5 inches
static pressure.

How do I determine the air flow with an existing fan and bin combination?

Assume that you have a 10-hp fan and a 12-foot grain depth. Enter the 10-hp row on the left column of Table 4. Follow this row to the right until you come to the column headed by a 12-foot depth, and read the estimated fan air delivery (1.86 cfm/bu.).

Should I have a vane-axial or centrifugal fan for the above bin reference?

Referring to Figure 3, enter the 12-foot grain depth line (along the bottom of the graph), and follow it upward till it intersects with an air flow curve that would correspond to 1.86 cfm/bu. (estimated point between the 1.5 and 2.0 cfm/bu. curves). Follow the intersect point horizontally to the left margin, and read the static pressure (2.8 inches).

You should choose a vane-axial fan because the static pressure is below 4.0-4.5 inches of water. The fan should deliver at least 12,622 cfm at 2.8 inches static pressure (1.86 cfm x 6786 bu., as listed for a 12-foot depth in Table 4).

How will a change in grain depth affect the air delivery of my existing fan?

Again assuming a 10-hp fan and a 12-foot grain depth in a 30-foot diameter bin, let's compare the total air flow with that required for grain depths of 6 feet and 16 feet. Table 4 shows the following values for a 10 hp fan:

  Grain depth        6 ft.        12 ft.         16 ft.
  Grain volume     3,393 bu.    6,786 bu.      9,048 bu.
  Est. air flow   4.23 cfm/bu   1.86 cfm/bu.  1.28 cfm/bu.
  Total air flow   14,352 cfm    12,622 cfm    11,581 cfm

The total air flow values are simply grain volume multiplied by cfm/bu. Note that total air flow increases as the grain depth and volume decrease. In this way, air flow per bushel and-drying potential are sharply increased.

What effect would doubling horsepower have on air flow?

Looking at the same 6-, 12- and 16-foot grain depth columns in Table 4, we see that doubling the fan horsepower from 10 to 20 hp increases the air delivery-- both per bushel and total--by only about one-third. Thus, roughly two-thirds of the horsepower (energy) is expended with no increase in air flow.

  Grain depth     6 ft.       12 ft.         16 ft.
  Grain volume  3,393 bu.     6,786 bu.     9,048 bu.
  10-hp fan    4.23 cfm/bu.  1.86 cfm/bu.  1.28 cfm/bu.
  20-hp fan    6.25 cfm/bu.  2.46 cfm/bu.  1.65 cfm/bu.

What, then, happened to this two-thirds of the additional 10 horsepower? It was converted into heat, because of the "churning" of the air that the fan produced as it worked to force the increased air flow through "the same size hole" (i.e., the bin diameter which did not change). Although this loss reflects a loss in air flow efficiency, it is not a total loss, since the added heat is useful in drying grain.

Performance data for two fans having the same horsepower and air flow capabilities can be added to estimate total system performance. Two smaller fans may actually deliver slightly more or less air flow than a larger fan of the same total horsepower, depending on the combined air flow characteristics of the two smaller units compared with the larger one. But the difference will usually be small.

DRYERATION AND BIN COOLING PERFORMANCE TABLE AND GUIDELINES

Since air flow rates for dryeration and bin cooling are below that required for bin drying, greater depths of grain (up to 50 feet) may be processed when air flow rates are 0.5 cfm/bu. Also, cooling fronts traverse the grain bed roughly 50 times faster than drying fronts. Thus, whereas grain spoilage is the limiting criterion for any drying bed over 20 feet deep (involving more than a point or two of moisture removal), the upper limits of cooling depths are determined largely by the cost of owning and operating the horsepower required to push air through the grain mass.

Using the Performance Table

Table 5 presents data to help estimate the horsepower required for dryeration and bin cooling structures. The data apply to both hopper- and flat-bottom storages. The critical consideration is to make sure that the air supply system is adequate--i.e., has sufficient perforated floor area, supply duct cross-sectional area and fan horsepower.

All static pressure values for a given air flow rate are the same for each corresponding grain depth, regardless of bin size. For instance, the static pressure for the 0.5 cfm/bu. air flow rate is 4.4 inches of water for a 30-foot grain depth at all bin diameters. The reason is that the air flow per bushel and grain depth are the same in all cases.

Doubling a bin's floor area doubles its bushel capacity for the same grain depth. But if twice the number of bushels is to be aerated at the same 0.5 cfm/bu., the total amount of air flow must also double. However, the velocity of air flowing through any one column of grain will be constant, so static pressure will also be constant.

In contrast, increasing the air flow rate from 0.5 to 0.75 cfm/bu. in the 30-foot diameter bin for a 30-foot grain depth, for instance, increases the static pressure from 4.4 to 7.5 inches. Pushing more air through the "same size hole" sharply increases air velocity, resulting in greater air drag and resistance. In this case, a centrifugal rather than a vane-axial fan should be used.

For example, consider a 24-foot diameter bin, filled to a 20-foot level. The holding capacity is shown in Table 5 to be 7238 bushels--a big day's run for a large grain farm. Reading across the 24-foot diameter, 20-foot grain depth line, note that 2.3 hp is required to deliver 0.5 cfm/bu. Doubling the air flow rate to 1.0 cfm/bu. requires 10.2 hp-almost a five-fold increase!

The amount of perforated surface area needed to deliver the required air into the grain is shown in the three righthand "duct area" columns of Table 5. If the perforated area shown for your cooling bin is too small, increase it to bring the air distribution system into the recommended range. If this is not possible, shift to a lower air flow rate or lower grain depth to reduce air flow to the capacity of the perforated surface area.

Estimating Required Horsepower and Surface Area

If the size of your cooling bin is not listed in Table 5, you can estimate the horsepower and perforated surface areas as follows:

1. Calculate the holding capacity of your bin for the grain depth desired, using a factor of 1.25 cu.ft./bu.

2. Select the bin diameter from Table 5 closest in bushel capacity for the same storage height, but larger than your unit.

3. Divide the bushel capacity of your bin by that of the bin in Table 5. (Remember, the bushel capacities of the two bins must be for the same fill height.) The result is the ratio of your bin size to the slightly larger unit of Table 5.

4. Read the horsepower and perforated surface area values for the larger bin from Table 5.

5. Multiply these larger bin horsepower and surface area values by the ratio in step 3 to find the values for your bin. The only restriction is that your bin must have a uniform cross-sectional area for its full height.

Table 5. Design Requirements for Air Flow Rates of 1/2, 3/4 and 1 Cfm/Bu. in Dryeration and Bin Cooling of Shelled Corn for Various Bin Diameters and Grain Depths.*



                        Air volume       Static pressure        Fan power          Duct area
Bin   Grain   Grain   -------------       -------------       -------------        ----------
dia.  depth  volume   1/2   3/4   1      1/2   3/4    1      1/2   3/4     1      1/2  3/4   1
--------------------------------------------------------------------------------------------------
ft.    ft.     bu.     cu.ft./min.           in. water             sq.~.               sq.in.

14     2.5     308    154   231  308    0.52  0.53   0.54    0.03   0.04   0.05    5     8   10
       5.0     616    308   462  616    0.57  0.62   0.67    0.06   0.09   0.13   10    15   21
       7.5     924    462   693  924    0.67  0.77   0.89    0.10   0.17   0.26   15    23   31
      10.0    1232    616   924  1232   0.83  1.03   1.28    0.16   0.30   0.50   21    31   41
      12.5    1539    770  1155  1539   1.03  1.36   1.80    0.25   0.49   0.87   26    38   51
      15.0    1847    924  1385  1847   1.31  1.85   2.17    0.38   0.81   1.26   31    46   62
      17.5    2155   1078  1616  2155   1.60  2.34   3.65    0.54   1.19   2.48   36    54   72
      20.0    2463   1232  1847  2463   2.06  3.08   4.40    0.80   1.79   3.41   41    62   82
      30.0    3695   1847  2771  3695   4.40  7.50  11.30    2.56   6.54  13.14   62    92  123
      40.0    4926   2463  3695  4926   8.30 14.90   ****    6.43  17.32   ****   82   123  ***
      50.0    6158   3079  4618  6158  14.00  ****   ****   13.56   ****   ****  103   ***  ***

18    2.5      509    254   382   509   0.52  0.53   0.54    0.04   0.06   0.09    8    13   17
      5.0     1018    509   763  1018   0.57  0.62   0.67    0.09   0.15   0.21   17    25   34
      7.5     1527    763  1145  1527   0.67  0.77   0.89    0.16   0.28   0.43   25    38   51
     10.0     2036   1018  1527  2036   0.83  1.03   1.28    0.27   0.49   0.82   34    51   68
     12.5     2545   1272  1909  2545   1.03  1.36   1.80    0.41   0.82   1.44   42    64   85
     15.0     3054   1527  2290  3054   1.31  1.85   2.17    0.63   1.33   2.09   51    76  102
     17.5     3563   1781  2672  3563   1.60  2.34   3.65    0.90   1.97   4.09   59    89  119
     20.0     4072   2036  3054  4072   2.06  3.08   4.40    1.32   2.96   5.64   68   102  136
     30.0     6107   3054  4580  6107   4.40  7.50  11.30    4.23  10.81  21.72  102   153  204
     40.0     8143   4072  6107  8143   8.30 14.90   ****   10.63  28.63   ****  136   204  ***
     50.0    10179   5089  7634 10179  14.00  ****   ****   22.42   ****   ****  170   ***  ***

21    2.5      693    346   520   693   0.52  0.53   0.54    0.06   0.09   0.12   12    17   23
      5.0     1385    693  1039  1385   0.57  0.62   0.67    0.12   0.20   0.29   23    35   46
      7.5     2078   1039  1559  2078   0.67  0.77   0.89    0.22   0.38   0.58   35    52   69
     10.0     2771   1385  2078  2771   0.83  1.03   1.28    0.36   0.67   1.12   46    69   92
     12.5     3464   1732  2598  3464   1.03  1.36   1.80    0.56   1.11   1.96   58    87  115
     15.0     4156   2078  3117  4156   1.31  1.85   2.17    0.86   1.81   2.84   69   104  139
     17.5     4849   2425  3637  4849   1.60  2.34   3.65    1.22   2.68   5.57   81   121  162
     20.0     5542   2771  4156  5542   2.06  3.08   4.40    1.80   4.03   7.67   92   139  185
     30.0     8313   4156  6235  8313   4.40  7.50  11.30    5.75  14.71  29.56  139   208  277
     40.0    11084   5542  8313 11084   8.30 14.90   ****   14.47  38.97   ****  185   277  ***
     50.0    13855   6927 10391 13855  14.00  ****   ****   30.52   ****   ****  231   ***  ***

24    2.5      905    452   679  905    0.52  0.53   0.54    0.07   0.11   0.15   15    23   30
      5.0     1810    905  1357  1810   0.57  0.62   0.67    0.16   0.26   0.38   30    45   60
      7.5     2714   1357  2036  2714   0.67  0.77   0.89    0.29   0.49   0.76   45    68   90
     10.0     3619   1810  2714  3619   0.83  1.03   1.28    0.47   0.88   1.46   60    90  121
     12.5     4524   2262  3393  4524   1.03  1.36   1.80    0.73   1.45   2.56   75   113  151
     15.0     5429   2714  4072  5429   1.31  1.85   2.17    1.12   2.37   3.71   90   136  181
     17.5     6333   3167  4750  6333   1.60  2.34   3.65    1.59   3.50   7.27  106   158  211
     20.0     7238   3619  5429  7238   2.06  3.08   4.40    2.35   5.26  10.02  121   181  241
     30.0    10857   5429  8143 10857   4.40  7.50  11.30    7.52  19.22  38.61  181   271  362
     40.0    14477   7238 10857 14477   8.30  14.90  ****   18.90  50.90   ****  241   362  ***
     50.0    18096   9048 13572 18096  14.00  ****   ****   39.86   ****   ****  302   ***  ***

27    2.5     1145    573   859  1145   0.52  0.53   0.54    0.09   0.14   0.19   19    29   38
      5.0     2290   1145  1718  2290   0.57  0.62   0.67    0.21   0.34   0.48   38    57   76
      7.5     3435   1718  2577  3435   0.67  0.77   0.89    0.36   0.62   0.96   57    86  115
     10.0     4580   2290  3435  4580   0.83  1.03   1.28    0.60   1.11   1.84   76   115  153
     12.5     5726   2863  4294  5726   1.03  1.36   1.80    0.93   1.84   3.24   95   143  191
     15.0     6871   3435  5153  6871   1.31  1.85   2.17    1.42   3.00   4.69  115   172  229
     17.5     8016   4008  6012  8016   1.60  2.34   3.65    2.02   4.43   9.21  134   200  267
     20.0     9161   4580  6871  9161   2.06  3.08   4.40    2.97   6.66  12.68  153   229  305
     30.0    13741   6871 10306 13741   4.40  7.50  11.30    9.51  24.32  48.86  229   344  458
     40.0    18322   9161 13741 18322   8.30 14.90   ****   23.93  64.43   ****  305   458  ***
     50.0    22902  11451 17177 22902  14.00  ****   ****   50.45   ****   ****  382   ***  ***

30    2.5     1414    707  1060  1414   0.52  0.53   0.54    0.12   0.18   0.24   24    35   47
      5.0     2827   1414  2121  2827   0.57  0.62   0.67    0.25   0.41   0.60   47    71   94
      7.5     4241   2121  3181  4241   0.67  0.77   0.89    0.45   0.77   1.19   71   106  141
     10.0     5655   2827  4241  5655   0.83  1.03   1.28    0.74   1.37   2.28   94   141  188
     12.5     7069   3534  5301  7069   1.03  1.36   1.80    1.15   2.27   4.00  118   177  236
     15.0     8482   4241  6362  8482   1.31  1.85   2.17    1.75   3.70   5.79  141   212  283
     17.5     9896   4948  7422  9896   1.60  2.34   3.65    2.49   5.46  11.37  165   247  330
     20.0    11310   5655  8482 11310   2.06  3.08   4.40    3.67   8.22  15.66  188   283  377
     30.0    16965   8482 12724 16965   4.40  7.50  11.30   11.74  30.03  60.32  283   424  565
     40.0    22620  11310 16965 22620   8.30 14.90   ****   29.54  79.54   ****  377   565  ***
     50.0    28274  14137 21206 28274  14.00  ****   ****   62.28   ****   ****  471   ***  ***

33    2.5     1711    855  1283  1711   0.52  0.53   0.54    0.14   0.21   0.29   29    43   57
      5.0     3421   1711  2566  3421   0.57  0.62   0.67    0.31   0.50   0.72   57    86  114
      7.5     5132   2566  3849  5132   0.67  0.77   0.89    0.54   0.93   1.44   86   128  171
     10.0     6842   3421  5132  6842   0.83  1.03   1.28    0.89   1.66   2.76  114   171  228
     12.5     8553   4277  6415  8553   1.03  1.36   1.80    1.39   2.75   4.84  143   214  285
     15.0    10264   5132  7698 10264   1.31  1.85   2.17    2.12   4.48   7.01  171   257  342
     17.5    11974   5987  8981 11974   1.60  2.34   3.65    3.01   6.61  13.75  200   299  399
     20.0    13685   6842 10264 13685   2.06  3.08   4.40    4.44   9.95  18.95  228   342  456
     30.0    20527  10264 15395 20527   4.40  7.50  11.30   14.21  36.33  72.99  342   513  684
     40.0    27370  13685 20527 27370   8.30 14.90   ****   35.74  96.24   ****  456   684  ***
     50.0    34212  17106 25659 34212  14.00  ****   ****   75.36   ****   ****  570   ***  ***

36    2.5     2036   1018  1527  2036   0.52  0.53   0.54    0.17  0.25    0.35   34    51   68
      5.0     4072   2036  3054  4072   0.57  0.62   0.67    0.37  0.60    0.86   68   102  136
      7.5     6107   3054  4580  6107   0.67  0.77   0.89    0.64  1.11    1.71  102   153  204
     10.0     8143   4072  6107  8143   0.83  1.03   1.28    1.06  1.98    3.28  136   204  271
     12.5    10179   5089  7634 10179   1.03  1.36   1.80    1.65  3.27    5.77  170   254  339
     15.0    12215   6107  9161 12215   1.31  1.85   2.17    2.52  5.33    8.34  204   305  407
     17.5    14250   7125 10688 14250   1.60  2.34   3.65    3.59  7.87   16.37  238   356  475
     20.0    16286   8143 12215 16286   2.06  3.08   4.40    5.28  11.84  22.55  271   407  543
     30.0    24429  12215 18322 24429   4.40  7.50  11.30   16.91  43.24  86.86  407   611  814
     40.0    32572  16286 24429 32572   8.30 14.90   ****   42.53  **8*    ****  543   ***  ***

40    2.5     2513   1257  1885  2513   0.52  0.53   0.54    0.21  0.31    0.43   42    63   84
      5.0     5027   2513  3770  5027   0.57  0.62   0.67    0.45  0.74    1.06   84   126  168
      7.5     7540   3770  5655  7540   0.67  0.77   0.89    0.79  1.37    2.11  126   188  251
     10.0    10053   5027  7540 10053   0.83  1.03   1.28    1.31  2.44    4.05  168   251  335
     12.5    12566   6283  9425 12566   1.03  1.36   1.80    2.04  4.03    7.12  209   314  419
     15.0    15080   7540 11310 15080   1.31  1.85   2.17    3.11  6.58   10.30  251   377  503
     17.5    17593   8796 13195 17593   1.60  2.34   3.65    4.43  9.72   20.21  293   440  586
     20.0    20106  10053 15080 20106   2.06  3.08   4.40    6.52 14.61   27.84  335   503  670
     30.0    30159  15080 22620 30159   4.40  7.50  11.30   20.88 53.38    ****  503   754  ***
     40.0    40213  20106 30159 40213   8.30 14.90   ****   52.51  ****    ****  670   ***  ***

42    2.5     2771   1385  2078  2771   0.52  0.53   0.54    0.23  0.35    0.47   46    69   92
      5.0     5542   2771  4156  5542   0.57  0.62   0.67    0.50  0.81    1.17   92   139  185
      7.5     8313   4156  6235  8313   0.67  0.77   0.89    0.88  1.51    2.33  139   208  277
     10.0    11084   5542  8313 11084   0.83  1.03   1.28    1.45  2.69    4.46  185   277  369
     12.5    13855   6927 10391 13855   1.03  1.36   1.80    2.25  4.45    7.85  231   346  462
     15.0    16625   8313 12469 16625   1.31  1.85   2.17    3.43  7.26   11.35  277   416  554
     17.5    19396   9698 14547 19396   1.60  2.34   3.65    4.88  10.71  22.28  323   485  647
     20.0    22167  11084 16625 22167   2.06  3.08   4.40    7.18  16.11  30.69  369   554  739
     30.0    33251  16625 24938 33251   4.40  7.50  11.30   23.02  58.85   ****  554   831  ***
     40.0    44334  22167 33251 44334   8.30 14.90   ****   57.89   ****   ****  739   ***  ***

48    2.5     3619   1810  2714  3619   0.52  0.53   0.54    0.30  0.45    0.61   60    90  121
      5.0     7238   3619  5429  7238   0.57  0.62   0.67    0.65  1.06    1.53  121   181  241
      7.5    10857   5429  8143 10857   0.67  0.77   0.89    1.14  1.97    3.04  181   271  362
     10.0    14477   7238 10857 14477   0.83  1.03   1.28    1.89  3.52    5.83  241   362  483
     12.5    18096   9048 13572 18096   1.03  1.36   1.80    2.93  5.81   10.25  302   452  603
     15.0    21715  10857 16286 21715   1.31  1.85   2.17    4.48  9.48   14.83  362   543  724
     17.5    25334  12667 19000 25334   1.60  2.34   3.65    6.38 13.99  29.10   422   633  844
     20.0    28953  14477 21715 28953   2.06  3.08   4.40    9.38 21.05  40.09   483   724  965
     30.0    43430  21715 32572 43430   4.40  7.50  11.30   30.06 76.87   ****   724   ***  ***
     40.0    57906  28953 43430 57906   8.30 14.90   ****   75.62  ****   ****   965   ***  ***
----------------------------------------------------------------------------------------------------
* Airflow resistance is based on ASAE standard data for clean shelled
corn, increased 50 percent for fire material and compaction plus 0.5
inches of water column allowance for duct and entrance loss.  Fan
horsepower is calculated on the basis of 50 percent "installed" fan
efficiency.

PLOTTING AIR FLOW SYSTEM PERFORMANCE

Figure 5 relates fan performance, grain depth and air flow rate simultaneously for a particular fan. The instructions for plotting the performance curve for your present or proposed fan are given with the graph.

The cfm-vs.-static-pressure data for the two 10-hp fans listed in Table 2 have been converted in Figure 5 into cfm/sq.ft. values for each static pressure level, assuming a 30-foot diameter bin. These values have been plotted in Figure 5 for both fans.

The two fan curves cross at about 4.6 inches of static pressure--the equal performance point--forming the basis for selecting fan type. The intersection of either fan curve with the grain depth and air flow rate curve specifies the system performance at that combination.

Fan curves for other sized units may be plotted similarly using the worksheet. Use thin paper or clear plastic overlay sheets to protect the original and reduce confusion.

FACTORS AFFECTING FAN PERFORMANCE

Drying Capacity vs. Grain Depth

It should be apparent from the previous examples and from Tables 6-16 that grain depth has a marked influence on drying system performance and, therefore, on drying capacity. If you are having drying capacity or grain spoilage problems in bin drying systems, reduce the grain depth! This reduces the static pressure and allows the fan to deliver more total air to a smaller quantity of grain. The higher air volume will then permit you to use higher temperatures (for the same limits on moisture), thereby further increasing your drying rate.

Many farmers don't like to batch dry in a bin at shallow depths, because their handling methods are not sized or convenient for frequent transfers of grain. However, in a given period of time and with the same equipment, you can dry roughly twice as much grain doing it in 4-foot deep batches as you could in 8-foot batches. Rather than assuming the drying system is at fault, maybe you should re-evaluate your grain transfer system to increase drying capacity.

Fines and Air Flow Uniformity

Distribution of fine material in grain influences the rate and distribution of air flow. Paradoxically, a perfect distribution of fines causes the highest air flow resistance, because particles of fine material are in every open space between all adjacent kernels throughout the bin. Such perfect distribution may result in as much as a 200-400 percent increase in air flow resistance, compared with grain distributed as loose fill. This does not mean, though, that the fan air volume will be halved or quartered.

We noted earlier from Table 2 that fan delivery drops off as air flow resistance (static pressure) increases, but not on a one-to-one basis. Most high-pressure grain drying fans do not drop off rapidly in air volume capacity until the static pressure becomes high enough that the fan begins to "stall out."

Non-uniform air distribution, caused by uneven deposit of fines, means non-uniform drying or cooling. The fan must operate longer to accomplish drying or cooling in high resistance areas--requiring extra energy, time and cost. Bin drying and cooling performance is very dependent on air flow. The management and distribution of fine materials should not be taken lightly.

Unusual Fan Horsepower Ratings

Manufacturers' horsepower listings on grain drying fans are sometimes confusing. For example, some fans show a dual rating, such as "10.0-12.5 hp." This stems from three practices.

First, some electric power suppliers restrict motor size on their lines to a maximum 7.5 or 10 hp, while others permit installing a dual-rated motor, as long as the lower rating falls within the prescribed restriction.

Second, axial-flow crop drying fans are "air-over" motor designs that generally supply added freedom in motor rating because of the increased cooling provided by the flowing air.

Third, fan horsepower depends on the pounds of air a fan moves per unit of time at a specified temperature. A fan moves the same volume of air in cold weather as in warm weather. But since cold air is denser than warm air (weighs more per cubic foot), the fan pumps more pounds of air in winter, requiring more power than in summer.

Thus, a fan may demand only 10 hp under one set of operating conditions early in the season, but may increase its demand to 12.5 hp as air becomes colder and drying circumstances change.

Figure 5. Fan/air system performance chart and example.

The two fan curves in the chart were developed from fan performance data similar to that supplied by all fan manufacturers. You may plot similar curves for your own specific fan(s) characteristics by following these instructions:

(Suggestion: Plot fan curves on clear overlay sheets to preserve the master chart for repeated use.)

Example: Fan horsepower = 10 hp

Floor area of 30 foot diameter bin = (30)2(3.1416)/4
= (900)(3.1416)/4
= 706.86 sq ft

   

                                                           Static pressure (inches water)
	-------------------------------------------------------------------------------------------------------------------------------------------
           1.0          1.5          2.0           2.5          3.0           3.5          4.0          4.5          5.0        5.5         6.0
        -------------------------------------------------------------------------------------------------------------------------------------------
        cfm   cfm/   cfm   cfm/   cfm   cfm/   cfm    cfm/   cfm   cfm/   cfm    cfm/   cfm   cfm/    cfm  cfm/   cfm  cfm/   cfm  cfm/  cfm  cfm/
             sq.ft.       sq.ft        sq.ft         sq.ft.       sq.ft.        sq.ft.       sq.ft.       sq.ft.      sq.ft.      sq.ft.     sq.ft.
---------------------------------------------------------------------------------------------------------------------------------------------------
Vane-  19,400 27.4  18,400 26.0  17,300 24.5  16,300  23.1  15,100  21.4  14,000 19.8  12,800  18.1    -    -     9,500 13.4   -    -    -      - 
axial
--------------------------------------------------------------------------------------------------------------------------------------------------
Centri-
fugal  13,600 19.2    -          13,000 18.4    -           12,000  17.0    -          11,000  15.6    -         10,000 14.1   -        8,500  12.0
---------------------------------------------------------------------------------------------------------------------------------------------------

Your Calculations: Fan Horsepower =

Floor area of _____ - foot diameter bin =

   

                                                           Static pressure (inches water)
	-------------------------------------------------------------------------------------------------------------------------------------------
           1.0          1.5          2.0           2.5          3.0           3.5          4.0          4.5          5.0        5.5         6.0
        -------------------------------------------------------------------------------------------------------------------------------------------
        cfm   cfm/   cfm   cfm/   cfm   cfm/   cfm    cfm/   cfm   cfm/   cfm    cfm/   cfm   cfm/    cfm  cfm/   cfm  cfm/   cfm  cfm/  cfm  cfm/
             sq.ft.       sq.ft        sq.ft         sq.ft.       sq.ft.        sq.ft.       sq.ft.       sq.ft.      sq.ft.      sq.ft.     sq.ft.
---------------------------------------------------------------------------------------------------------------------------------------------------
Vane- 
axial
--------------------------------------------------------------------------------------------------------------------------------------------------
Centri-
fugal 
---------------------------------------------------------------------------------------------------------------------------------------------------

Bin Drying Air Flow Rate Performance Tables

Table 6. Air Flow Rates at Various Fan Sizes and Grain Depths for Drying Shelled Corn and Soybeans In a 14-Foot Diameter Bin (Average commercial fan performance and 1.5 packing factor) .*



           Air flow rate needed for a grain depth (and corresponding bushel volume) of--
        ------------------------------------------------------------------------------------
Fan    2 ft.  4 ft.  6 ft.  8 ft.  10 ft.  12 ft. 14 ft.  16 ft. 18 ft.  20 ft.  22 ft. 24 ft.
 hp    (246)  (493)  (739)  (985)  (1232)  (1478) (1724) (1970) (2217)  (2463)  (2709) (2956)
-----------------------------------------------------------------------------------------------
                                        cfm/bushel**
0.33   6.09   2.92   1.87   1.34    1.03    .83    .68    .57    .49     .42     .37    .33
0.5    7.95   3.81   2.36   1.65    1.24    .97    .78    .64    .54     .46     .40    .35
0.75   8.75   4.24   2.65   1.88    1.39   1.08    .86    .71    .60     .52     .45    .39
  
1.0   11.59   5.46   3.39   2.36    1.76   1.36   1.08    .87    .73     .61     .53    .46
1.5   16.18   7.20   4.29   2.94    2.17   1.68   1.35   1.12    .94     .81     .70    .61
2.0   18.66   8.26   5.02   3.42    2.52   1.95   1.57   1.30   1.09     .93     .81    .71
			                                       ----------------------------
3.0   23.68   10.17  5.99   4.02    2.93   2.25   1.79   1.47 | 1.26    1.10     .97    .87
4.0   27.43   11.31  6.51   4.34    3.13   2.39   1.89   1.54 | 1.29    1.11     .98    .88
				  ----------------------------|
5.0   32.50   13.03  7.44   4.89 |  3.53   2.74   2.21   1.84   1.56    1.34    1.18   1.04
	             -------------
7.5   36.85   14.47 | 8.45  5.79    4.25   3.29   2.64   2.18   1.83   1.59     1.40   1.24
	     ------	
10.0  41.17 | 16.97  9.87   6.66    4.88   3.77   3.02   2.51   2.13   1.84     1.61   1.42
12.5  44.25 | 17.84 10.39   7.03    5.18   4.03   3.24   2.70   2.30   1.99     1.74   1.54
	    | 	
15.0  47.66 | 18.41 10.90   7.40    5.46   4.27   3.47   2.89   2.45   2.13     1.88   1.67
------------
20.0  50.03   20.81 12.08   8.21    6.05   4.70   3.81   3.17   2.69   2.32     2.04   1.82
25.0  52.57   21.96 12.95   8.79    6.48   5.12   4.19   3.51   3.00   2.61     2.29   2.03

30.0  57.18   23.83 13.94   9.52    7.08   5.55   4.51   3.77   3.21   2.77     2.43   2.16
40.0  66.06   26.58 15.51  10.61    7.85   6.10   4.95   4.13   3.53   3.08     2.70   2.39
50.0  72.49   29.09 16.86  11.46    8.46   6.61   5.37   4.49   3.83   3.31     2.89   2.55
--------------------------------------------------------------------------------------------
   *and **  See footnotes accompanying Table 4.

Table 7. Air Flow Rates at Various Fan Sizes and Grain Depths for Drying Shelled Corn and Soybeans in a 18-Foot Diameter Bin (Average commercial fan performance and 1.5 packing factor).*



           Air flow rate needed for a grain depth (and corresponding bushel volume) of--
        ------------------------------------------------------------------------------------
Fan    2 ft.  4 ft.  6 ft.  8 ft.  10 ft.  12 ft. 14 ft.  16 ft.  18 ft. 20 ft.  22 ft. 24 ft.
 hp   (407)  (814)  (1221) (1629)  (2036)  (2443) (2850) (3257)  (3664) (4072)  (4479) (4886)
-----------------------------------------------------------------------------------------------
                               cfm/bushel**

0.33   3.76    1.84   1.20    .88    .69     .56    .47     .40    .35    .31     .27    .25
0.5    4.90    2.40   1.56   1.15    .88     .71    .59     .50    .43    .37     .33    .29
0.75   5.34    2.64   1.74   1.27    .98     .79    .66     .56    .48    .42     .36    .32
 
1.0    7.10    3.51   2.27   1.65   1.28    1.02    .84     .70    .60    .52     .45    .40
1.5   10.23    4.93   3.15   2.22   1.68    1.33   1.08     .90    .76    .65     .57    .50
2.0   12.11    5.70   3.58   2.54   1.94    1.55   1.27    1.07    .91    .78     .68    .60

3.0   15.62    7.28   4.49   3.14   2.37    1.87   1.51    1.26   1.07    .92     .80    .71
4.0   19.20    8.54   5.13   3.52   2.61    2.03   1.64    1.36   1.15    .99     .86    .75
										--------------
5.0   23.53   10.26   6.06   4.09   3.03    2.34   1.87    1.54   1.29   1.10  |  .97    .86
					  -------------------------------------
7.5   27.61   11.80   6.89   4.63   3.37 |  2.63   2.16   1.81   1.54   1.33     1.16   1.03
			    -------------
10.0  31.92   13.30   7.74 | 5.40   4.04    3.15   2.55   2.11   1.79   1.54     1.34   1.18
12.5  34.96   14.34   8.32 | 5.73   4.26    3.33   2.70   2.24   1.90   1.64     1.43   1.27
			   |		
15.0  39.44   15.54   8.93 | 5.91   4.41    3.48   2.84   2.37   2.01   1.73     1.52   1.34
                     ------
20.0  42.19   16.36 | 9.63   6.74   5.01    3.90   3.17   2.64   2.25   1.94     1.70   1.50
25.0  45.08   17.15 |10.12   7.05   5.30    4.18   3.41   2.84   2.42   2.09     1.83   1.62
            --------
30.0  48.22 | 18.06  11.07   7.69   5.74    4.52   3.68   3.08   2.62   2.28     2.01   1.78
40.0  50.24 | 21.10  12.58   8.62   6.40    5.03   4.10   3.43   2.94   2.56     2.25   1.99
50.0  54.46 | 22.95  13.81   9.46   7.01    5.49   4.46   3.73   3.18   2.76     2.43   2.16
-----------------------------------------------------------------------------------------------
   *and **  See footnotes accompanying Table 4.

Table 8. Air Flow Rates at Various Fan Sizes and Grain Depths for Drying Shelled Corn and Soybeans in a 21-Foot Diameter Bin (Average commercial fan performance and 1.5 packing factor).*



           Air flow rate needed for a grain depth (and corresponding bushel volume) of--
        ------------------------------------------------------------------------------------
Fan    2 ft.  4 ft.  6 ft.  8 ft.  10 ft.  12 ft. 14 ft.  16 ft.  18 ft. 20 ft.  22 ft. 24 ft.
 hp   (554)  (1108) (1663) (2217)  (2771) (3325) (3879)  (4433)  (4988) (5542)  (6096)  (6650)
------------------------------------------------------------------------------------------------
                                cfm/bushel**

0.33   2.78   1.37    .90   .66     .52    .43    .36      .31    .27    .24     .22     .20
0.5    3.63   1.79   1.17   .87     .68    .56    .47      .40    .35    .30     .27     .24
0.75   3.94   1.96   1.29   .96     .77    .62    .52      .45    .39    .34     .30     .27

1.0    5.24   2.60   1.72  1.27     .99    .81    .68      .58    .50    .44     .39     .35
1.5    7.58   3.73   2.42  1.76    1.36   1.08    .89      .75    .64    .56     .49     .44
2.0    9.12   4.38   2.82  2.03    1.56   1.25   1.04      .88    .76    .66     .58     .51

3.0   11.70   5.67   3.61  2.57    1.97   1.57   1.29     1.09    .94    .81     .71     .62
4.0   14.56   6.85   4.25  2.97    2.24   1.77   1.44     1.20   1.03    .89     .78     .69
5.0   18.37   8.35   5.11  3.56    2.63   2.05   1.67     1.39   1.18   1.02     .89     .78
								-----------------------------
7.5   21.84   9.80   5.92  4.07    3.00   2.33   1.87     1.55 | 1.31   1.15    1.02     .91
					 ----------------------
10.0  25.82  11.34   6.72  4.59    3.38 | 2.70   2.22     1.86   1.58   1.37    1.20    1.06
12.5  28.69  12.43   7.27  4.96    3.64 | 2.88   2.35     1.96   1.67   1.45    1.27    1.13
					|					
15.0  33.74  13.87   8.01  5.38    3.93 | 2.97   2.43     2.03   1.74   1.52    1.34    1.19
				--------
20.0  37.04  14.73   8.47  5.64 |  4.26   3.39   2.79     2.34   1.97   1.71    1.50    1.33
			   ------			
25.0  39.75  15.66   8.96 |5.93    4.48   3.56   2.92     2.46   2.11   1.83    1.61    1.44
			  |
30.0  43.20  16.79   9.41 |6.44    4.92   3.92   3.20     2.68   2.29   1.99    1.75    1.56
		    ------
40.0  45.74  17.42 |10.66  7.49    5.62   4.43   3.61     3.02   2.57   2.23    1.96    1.75
50.0  50.42  18.72 |11.56  8.20    6.17   4.86   3.96     3.32   2.83   2.45    2.15    1.91
------------------------------------------------------------------------------------------------
   *and **  See footnotes accompanying Table 4.

Table 9. Air Flow Rates at Various Fan Sizes and Grain Depths for Drying Shelled Corn and Soybeans in a 24-Foot Diameter Bin (Average commercial fan performance and 1.5 packing factor).*



           Air flow rate needed for a grain depth (and corresponding bushel volume) of--
        ------------------------------------------------------------------------------------
Fan    2 ft.  4 ft.  6 ft.  8 ft.  10 ft.  12 ft. 14 ft.  16 ft.  18 ft. 20 ft.  22 ft. 24 ft.
hp     (724) (1448) (2171) (2895)  (3619) (4343)  (5067)  (5791)  (6514) (7238)  (7962) (8686)
------------------------------------------------------------------------------------------------
                                cfm/bushel**

0.33   2.14   1.06   .70     .52     .41    .34    .29    .25      .22    .19     .17    .16
0.5    2.79   1.38   .91     .68     .53    .44    .37    .32      .28    .25     .22    .20
0.75   3.02   1.50  1.00     .74     .59    .49    .42    .36      .31    .28     .25    .22

1.0    4.02   2.00  1.32     .99     .78    .64    .54    .47     .41     .36     .32    .29
1.5    5.83   2.88  1.90    1.39    1.09    .89    .74    .63     .54     .48     .42    .38
2.0    7.07   3.43  2.22    1.62    1.26   1.02    .85    .73     .63     .55     .49    .44

3.0    9.04   4.44  2.90    2.11    1.63   1.31   1.08    .92     .79    .69      .61    .54
4.0   11.33   5.48  3.50    2.50    1.91   1.52   1.25   1.06     .90    .78      .68    .60
5.0   14.48   6.81  4.27    3.02    2.29   1.82   1.48   1.24    1.05    .91      .80    .71
 
7.5   17.33   8.08  5.01    3.51    2.64   2.08   1.69   1.41    1.19   1.03      .90    .80
							-------------------------------------
10.0  20.56   9.46  5.81    4.01    2.99   2.35   1.90 | 1.59    1.38   1.21     1.07    .95
12.5  23.03  10.51  6.38    4.36    3.25   2.54   2.05 | 1.71    1.47   1.28     1.13   1.00
						       |
15.0  28.49  12.21  7.18    4.85    3.56   2.76   2.22 | 1.76    1.52   1.32     1.17   1.04
						-------|
20.0  31.51  13.32  7.68    5.15    3.77   2.90 | 2.38   2.01    1.73   1.52     1.34   1.19
25.0  34.62  14.36  8.23    5.50    3.99   3.04 | 2.51   2.12    1.82   1.59     1.41   1.26
					 -------
30.0  38.41  15.32  8.84    5.84    4.20 | 3.31   2.75   2.33    2.01   1.75     1.55   1.38
			   --------------|
40.0  42.54  16.16  9.18  | 6.34    4.86   3.89   3.18   2.67    2.29   1.99     1.75   1.55
50.0  46.69  17.59  9.91  | 6.86    5.28   4.25   3.51   2.95    2.52   2.19     1.93   1.71
------------------------------------------------------------------------------------------------
   *and **  See footnotes accompanying Table 4.

Table 10. Air Flow Rates at Various Fan Sizes and Grain Depths for Drying Shelled Corn and Soybeans in a 27-Foot Diameter Bin (Average commercial fan performance and 1.5 packing factor).*



           Air flow rate needed for a grain depth (and corresponding bushel volume) of--
        ------------------------------------------------------------------------------------
Fan    2 ft.  4 ft.  6 ft.  8 ft.  10 ft.  12 ft. 14 ft.  16 ft.  18 ft. 20 ft.  22 ft. 24 ft.
 hp    (916) (1832) (2748) (3664)  (4580)  (5497) (6413)  (7329)  (8245) (9161) (10077) (10993)
------------------------------------------------------------------------------------------------
                                            cfm/bushel** 

0.33   1.70    .84    .56   .41     .33     .27     .23    .20     .18    .16     .14    .13
0.5    2.21   1.10    .72   .54     .43     .35     .30    .26     .23    .21     .18    .17
0.75   2.39   1.19    .79   .59     .47     .39     .33    .29     .26    .23     .21    .19

1.0    3.18   1.58   1.05   .79     .63     .52     .44    .38     .33    .30     .27    .24
1.5    4.62   2.29   1.51  1.13     .89     .73     .61    .53     .46    .41     .36    .32
2.0    5.63   2.75   1.80  1.32    1.03     .84     .71    .61     .53    .47     .42    .37

3.0    7.18   3.54   2.32  1.72    1.35    1.09     .91    .77     .67    .59     .52    .47
4.0    9.00   4.43   2.88  2.10    1.62    1.30    1.08    .91     .78    .68     .60    .53
5.0   11.61   5.59   3.57  2.56    1.97    1.58    1.30   1.10     .92    .82     .72    .63
  
7.5   13.94   6.67   4.23  3.01    2.30    1.83    1.50   1.26    1.08    .94     .82    .73
										       --------
10.0  16.52   7.92   4.94  3.50    2.64    2.09    1.70   1.43    1.22   1.06     .93  | .83
12.5  18.77   8.81   5.49  3.85    2.89    2.26    1.85   1.55    1.32   1.14    1.00  | .89
										       |
15.0  23.66  10.63   6.38  4.38   3.24     2.51    2.03   1.68    1.43   1.23    1.07  | .92
								-----------------------|
20.0  26.69  11.76   6.98  4.72   3.45     2.67    2.15   1.78 |  1.50   1.32    1.17   1.05
25.0  30.23  12.78   7.56  5.07   3.69     2.86    2.28   1.87 |  1.58   1.39    1.23   1.10
							-------|
30.0  33.89  14.02   8.11  5.44   3.97     3.03    2.41 | 1.99    1.73   1.52    1.35   1.22
					 ---------------|
40.0  37.25  14.95   8.58  5.71   4.13  |  3.33    2.77   2.35    2.03   1.77    1.56   1.39
50.0  43.54  16.70   9.33  6.26   4.45  |  3.61    3.01   2.57    2.23   1.96    1.73   1.54
------------------------------------------------------------------------------------------------
  *  and **  See footnotes accompanying Table 4.

Table 11. Air Flow Rates at Various Fan Sizes and Grain Depths for Drying Shelled Corn and Soybeans in a 30-Foot Diameter Bin (Average commercial fan performance and 1.5 packing factor).*



          Air flow rate needed for a grain depth (and corresponding bushel volume) of--
	---------------------------------------------------------------------------------
 Fan   2 ft.  4 ft.  6 ft.  8 ft.  10 ft. 12 ft. 14 ft. 16 ft. 18 ft.  20 ft.  22 ft.  24 ft.
 hp   (1131) (2262) (3393) (4524) (5655) (6786) (7917) (9048) (10179) (11310) (12441) (13572)
-----------------------------------------------------------------------------------------------
                                            cfm/bushel**

0.33  1.38    .68    .45    .34    .27    .22     .19    .16     .14    .13     .12      .11
0.5   1.80    .89    .59    .44    .35    .29     .25    .21     .19    .17     .15      .14
0.75  1.94    .97    .64    .48    .38    .32     .27    .24     .21    .19     .17      .16

1.0   2.58   1.29    .85    .64    .51    .42     .36    .31     .28    .25     .22      .20
1.5   3.75   1.86   1.23    .92    .73    .60     .51    .44     .39    .35     .31      .28
2.0   4.58   2.25   1.48   1.09    .86    .70     .60    .51     .45    .40     .36      .32

3.0   5.83   2.89   1.90   1.41   1.11    .92     .77    .66     .58    .51     .45      .41
4.0   7.31   3.62   2.37   1.74   1.36   1.10     .92    .78     .68    .59     .53      .47
5.0   9.43   4.63   3.00   2.18   1.69   1.36    1.13    .96     .83    .72     .64      .57

7.5  11.39   5.54   3.57   2.58   1.99   1.60    1.33    1.12     .97   .85     .75      .66
10.0 13.51   6.58   4.23   3.02   2.32   1.86    1.53    1.28    1.10   .96     .84      .75
12.5 15.43   7.37   4.71   3.36   2.56   2.04    1.67    1.39    1.19  1.04     .92      .81

15.0 19.76   9.18   5.64   3.92   2.93   2.30    1.86    1.55    1.32  1.14     .99      .88
20.0 22.46  10.20   6.25   4.30   3.18   2.46    1.99    1.65    1.39  1.20    1.05      .93
25.0 25.93  11.31   6.77   4.66   3.44   2.65    2.12    1.76    1.49  1.27    1.10      .97
									     ------------------
30.0 29.53  12.66   7.45   5.02   3.68   2.86    2.28    1.87    1.57  1.34  | 1.18     1.06
						       ----------------------|
40.0 33.00  13.78   7.97   5.33   3.89   2.99    2.38  | 2.04    1.63  1.56    1.39     1.25
50.0 39.39  15.57   8.92   5.87   4.26   3.27    2.58  | 2.21    1.92  1.70    1.52     1.36
-----------------------------------------------------------------------------------------------
   *and **  See footnotes accompanying Table 4.

Table 12. Air Flow Rates at Various Fan Sizes and Grain Depths for Drying Shelled Corn and Soybeans in a 33-Foot Diameter Bin (Average commercial fan performance and 1.5 packing factor).*



          Air flow rate needed for a grain depth (and corresponding bushel volume) of--
	------------------------------------------------------------------------------------
Fan   2 ft.   4 ft.  6 ft.  8 ft. 10 ft. 12 ft. 14 ft.  16 ft.  18 ft.  20 ft.   22 ft.  24 ft.
hp   (1368)  (2737) (4105) (5474) (6842) (8211) (9579) (10948) (12316) (13685) (15053) (16422)
--------------------------------------------------------------------------------------------------
                                   cfm/bushel**

0.33   1.14    .57    .38    .28   .22    .18    .16    .14     .12     .11      .10     .09
0.5    1.49    .74    .49    .37   .29    .24    .21    .18     .16     .14      .13     .12
0.75   1.60    .80    .53    .40   .32    .26    .23    .20     .17     .16      .14     .13

1.0    2.13   1.06    .71    .53   .42    .35    .30    .26     .23      .21     .19     .17
1.5    3.10   1.54   1.02    .76   .61    .50    .43    .37     .33      .29     .26     .24
2.0    3.80   1.88   1.23    .91   .72    .59    .50    .43     .38      .34     .31     .28

3.0    4.83   2.40   1.58   1.18   .93    .77    .65    .57     .50      .44     .39     .35
4.0    6.06   3.00   1.98   1.46  1.15    .95    .79    .68     .59      .52     .46     .42
5.0    7.81   3.88   2.53   1.85  1.44   1.17    .98    .83     .72      .63     .56     .50
 
7.5    9.43   4.65   3.03   2.22  1.73   1.40   1.17    .99     .86      .75     .66     .59
10.0  11.23   5.51   3.60   2.63  2.03   1.63   1.36   1.15     .99      .87     .77     .68
12.5  12.88   6.25   4.02   2.92  2.26   1.81   1.50   1.27    1.09      .95     .83     .74

15.0  16.50   7.87   4.97   3.50  2.64   2.09   1.71   1.43    1.22     1.05     .92     .82
20.0  18.94   8.88   5.51   3.87  2.91   2.28   1.84   1.53    1.30     1.12     .98     .87
25.0  22.21  10.09   6.08   4.21  3.14   2.48   1.99   1.64    1.39     1.20    1.05     .93

30.0  25.76  11.37   6.79   4.65  3.42   2.65   2.13   1.77    1.50     1.28    1.11     .98
								     ------------------------
40.0  29.02  12.57   7.38   4.98  3.64   2.81   2.25   1.85    1.56  |  1.36    1.22    1.10
50.0  35.76  14.74   8.37   5.61  4.04   3.09   2.48   2.03    1.69  |  1.47    1.32    1.19
--------------------------------------------------------------------------------------------------
   *and **  See footnotes accompanying Table 4.

Table 13. Air Flow Rates at Various Fan Sizes and Grain Depths for Drying Shelled Corn and Soybeans in a 36-Foot Diameter Bin (Average commercial fan performance and 1.5 packing factor).*



           Air flow rate needed for a grain depth (and corresponding bushel volume) of--
        -----------------------------------------------------------------------------------
 Fan   2 ft.  4 ft.  6 ft.  8 ft.  10 ft. 12 ft. 14 ft.  16 ft.  18 ft.  20 ft.  22 ft.  24 ft.
 hp   (1629) (3257) (4886) (6514) (8143) (9772) (11400) (13029) (14657) (16286) (17915) (19543)
-------------------------------------------------------------------------------------------------
                                  cfm/bushel**

0.33   .96    .48    .32    .24    .19    .16    .13     .12     .10     .09     .08      .08
0.5   1.25    .62    .41    .31    .25    .20    .17     .15     .13     .12     .11      .10
0.75  1.35    .67     45    .33    .27    .22    .19     .17     .15     .13     .12      .11

1.0   1.79    .90    .60    .45    .36    .30    .25     .22     .20     .18     .16      .15
1.5   2.61   1.30    .86    .64    .51    .43    .36     .32     .28     .25     .23      .20
2.0   3.20   1.58   1.05    .78    .61    .51    .43     .37     .33     .29     .26      .24

3.0   4.07   2.02   1.34   1.00    .79    .66    .56     .48     .43     .38     .34      .31
4.0   5.10   2.53   1.68   1.25    .99    .81    .69     .59     .52     .46     .41      .37
5.0   6.57   3.27   2.15   1.58   1.24   1.01    .85     .73     .64     .56     .50      .45

7.5   7.93   3.95   2.58   1.90   1.49   1.21   1.02     .87     .75     .66     .59      .53
10.0  9.48   4.67   3.07   2.26   1.78   1.44   1.20    1.02     .89     .78     .69      .61
12.5 10.85   5.33   3.46   2.53   1.98   1.61   1.34    1.14     .98     .86     .76      .68

15.0 13.95   6.79   4.33   3.12   2.38   1.89   1.56    1.31    1.12     .98     .86      .76
20.0 16.20   7.72   4.86   3.46   2.63   2.09   1.71    1.43    1.21    1.05     .92      .81
25.0 19.13   8.88   5.47   3.81   2.87   2.26   1.85    1.55    1.31    1.13     .98      .87
   
30.0 22.27  10.12   6.16   4.26   3.17   2.47   2.00    1.65    1.40    1.21    1.06      .94
40.0 25.52  11.32   6.79   4.64   3.41   2.64   2.12    1.76    1.48    1.27    1.11      .97
50.0 32.36  13.52   7.94   5.26   3.86   2.96   2.35    1.93    1.63    1.40    1.21     1.05
-------------------------------------------------------------------------------------------------
   *and **  See footnotes accompanying Table 4.

Table 14. Air Flow Rates at Various Fan Sizes and Grain Depths for Drying Shelled Corn and Soybeans in a 40-Foot Diameter Bin (Average commercial fan performance and 1.5 packing factor).*




            Air flow rate needed for a grain depth (and corresponding bushel volume) of--
       ---------------------------------------------------------------------------------------
Fan   2 ft.  4 ft.  6 ft.  8 ft.  10 ft.  12 ft.  14 ft.  16 ft.  18 ft.  20 ft.  22 ft.  24 ft.
hp   (2011) (4021) (6032) (8042) (10053) (12064) (14074) (16085) (18096) (20106) (22117) (24127)
---------------------------------------------------------------------------------------------------
                                           cfm/bushel**

0.33   .78   .39    .26     .19   .15     .13      .11     .09    .08     .08      .07     .06
0.5   1.01   .50    .34     .25   .20     .17      .14     .12    .11     .10      .09     .08
0.75  1.09   .55    .36     .27   .22     .18      .15     .13    .12     .11      .10     .09

1.0   1.45   .73    .48     .36   .29     .24      .21     .18    .16     .14      .13     .12
1.5   2.12  1.05    .70     .52   .42     .35      .30     .26    .23     .21      .19     .17
2.0   2.60  1.29    .85     .63   .50     .42      .35     .31    .27     .24      .22     .20

3.0   3.30  1.64   1.09     .81   .65     .54      .46     .40    .35     .31      .28     .26
4.0   4.13  2.06   1.37    1.02   .81     .67      .57     .49    .43     .39      .35     .31
5.0   5.32  2.65   1.76    1.31  1.03     .85      .72     .62    .54     .48      .43     .39

7.5   6.43  3.20   2.12    1.57  1.24    1.01      .85     .73    .64     .57     .51      .46
10.0  7.70  3.81   2.52    1.87  1.47    1.21     1.02     .87    .76     .67     .59      .53
12.5  8.79  4.37   2.87    2.11  1.66    1.35     1.14     .98    .85     .75     .66      .59

15.0 11.37  5.60   3.64    2.65  2.06    1.66     1.37    1.16   1.00     .88     .77      .69
20.0 13.34  6.40   4.14    2.97  2.29    1.84     1.52    1.29   1.10     .96     .85      .75
25.0 15.72  7.48   4.74    3.35  2.53    2.02     1.65    1.39   1.19    1.04     .92      .81

30.0 18.49  8.67   5.38    3.78  2.84    2.24     1.83    1.52   1.30    1.12     .98      .87
40.0 21.49  9.80   6.01    4.17  3.11    2.43     1.96    1.63   1.38    1.19    1.04      .92
50.0 28.39 12.15   7.19    4.92  3.57    2.76     2.22    1.83   1.53    1.31    1.14     1.01
---------------------------------------------------------------------------------------------------
   *and **  See footnotes accompanying Table 4.

Table 15. Air Flow Rates at Various Fan Sizes and Grain Depths for Drying Shelled Corn and Soybeans in a 42-Foot Diameter Bin (Average commercial fan performance and 1.5 packing factor).*




            Air flow rate needed for a grain depth (and corresponding bushel volume) of--
        -------------------------------------------------------------------------------------
 Fan   2 ft.  4 ft.  6 ft.  8 ft.  10 ft.  12 ft.  14 ft.  16 ft.  18 ft.  20 ft.  22 ft.  24 ft.
 hp   (2217) (4433) (6650) (8867) (11084) (13300) (15517) (17734) (19950) (22167) (24384) (26601)
----------------------------------------------------------------------------------------------------
                                    cfm/bushel**

0.33   .70    .35    .23    .17     .14    .12     .10     .09    .08      .07     .06     .06
0.5    .92    .48    .30    .23     .18    .15     .13     .11    .10      .09     .08     .07
0.75   .99    .49    .33    .25     .20    .16     .14     .12    .11      .10     .09     .08
 
1.0   1.32    .66    .44   .33     .26    .22     .19     .16     .14     .13     .12      .11
1.5   1.92    .96    .64   .48     .38    .32     .27     .24     .21     .19     .17      .15
2.0   2.36   1.17    .78   .58     .46    .38     .32     .28     .25     .22     .20      .18

3.0   2.99   1.49    .99   .74     .59    .49     .42     .36     .32     .29     .26      .24
4.0   3.75   1.87   1.24   .93     .74    .61     .52     .45     .40     .35     .32      .29
5.0   4.83   2.41   1.60  1.19     .94    .78     .66     .57     .50     .44     .40      .36

7.5   5.83   2.91   1.93  1.43    1.13    .93     .79     .68     .59     .53     .47      .42
10.0  6.99   3.47   2.29  1.70    1.35   1.11     .94     .80     .70     .62     .55      .50
12.5  7.98   3.98   2.62  1.93    1.52   1.24    1.05     .90     .79     .69     .62      .55

15.0 10.33   5.10   3.35  2.44    1.90   1.55    1.29    1.10     .95     .83     .73      .65
20.0 12.17   5.87   3.80  2.76    2.13   1.72    1.43    1.21    1.05     .91     .81      .72
25.0 14.33   6.89   4.39  3.15    2.39   1.90    1.57    1.32    1.13     .99     .87      .78
 
30.0 16.94   8.03   5.02  3.56    2.69   2.13    1.74    1.46    1.24    1.08     .94      .84
40.0 19.77   9.11   5.64  3.95    2.96   2.33    1.88    1.57    1.33    1.15    1.00      .89
50.0 26.34  11.45   6.84  4.71    3.47   2.66    2.14    1.77    1.49    1.28    1.11      .97
----------------------------------------------------------------------------------------------------
   *and **  See footnotes accompanying Table 4.

Table 16. Air Flow Rates at Various Fan Sizes and Grain Depths for Drying Shelled Corn and Soybeans in a 48-Foot Diameter Bin (Average commercial fan performance and 1.5 packing factor).*



           Air flow rate needed for a grain depth (and corresponding bushel volume) of--
	-------------------------------------------------------------------------------------
Fan   2 ft.  4 ft.  6 ft.  8 ft.   10 ft.  12 ft.  14 ft.  16 ft.  18 ft.  20 ft.  22 ft.  24 ft.
hp   (2895) (5791) (8686) (11581) (14476) (17372) (20267) (23162) (26058) (28953) (31848) (34744)
----------------------------------------------------------------------------------------------------
                                    cfm/bushel**

0.33   .54   .27     .18   .13     .11     .09     .08    .07     .06      .05      .05      .04
0.5    .70   .35     .23   .17     .14     .12     .10    .09     .08      .07      .06      .06
0.75   .76   .38     .25   .19     .15     .13     .11    .09     .08      .08      .07      .06

1.0   1.01   .50     .34   .25     .20     .17     .14    .13     .11      .10      .09      .08
1.5   1.47   .73     .49   .37     .29     .24     .21    .18     .16      .14      .13      .12
2.0   1.81   .90     .60   .45     .35     .29     .25    .22     .19      .17      .16      .14

3.0   2.29  1.14     .76   .57     .45     .38     .32    .28     .25     .22       .20      .18
4.0   2.88  1.43     .95   .71     .57     .47     .40    .35     .31     .28       .25      .23
5.0   3.70  1.85    1.23   .92     .73     .61     .52    .45     .39     .35       .32      .29

7.5   4.47  2.23    1.48  1.11     .88     .73     .62    .54     .47     .42       .38      .34
10.0  5.37  2.67    1.77  1.32    1.05     .87     .74    .64     .56     .50       .45      .41
12.5  6.11  3.05    2.03  1.50    1.19     .98     .83    .72     .63     .56       .50      .46

15.0  7.94  3.94    2.60  1.93    1.52    1.24    1.04    .90     .78     .69       .61       .55
20.0  9.40  4.60    3.00  2.21    1.73    1.41    1.18   1.01     .88     .77       .68       .61
25.0 11.09  5.43    3.52  2.56    1.99    1.61    1.33   1.13     .97     .85       .76       .67

30.0 13.26  6.36    4.10  2.94    2.26    1.82    1.50   1.27    1.09     .95       .84       .75
40.0 15.59  7.36    4.65  3.32    2.53    2.02    1.66   1.39    1.19    1.03       .91       .80
50.0 21.18  9.73    5.87  4.09    3.05    2.41    1.96   1.61    1.36    1.17      1.03       .91
----------------------------------------------------------------------------------------------------
   *and **  See footnotes accompanying Table 4.

Related Publications

Single copies of the following Purdue Extension publications dealing with grain drying and handling are available to Indiana residents from their county Cooperative Extension Service offices or by writing to the CES Mailing Room, 310 S. Second St., Lafayette, IN 47905-1232:

AE-90, "Managing Grain (or Year-Round Storage"

AE-91, "Temporary Corn Storage in Outdoor Piles"

AE-93, "Adapting Silage Silos for Dry Grain Storage"

AE-107,"Dryeration and Bin Cooling tor Grain"

AE-108,"Solar Heat tor Grain Drying"

AED-20,"Managing Dry Grain in Storage"

ID-96, "Double Cropping Winter Wheat and Soybeans in Indiana"

The following Midwest Plan Service publications are available at the cost indicated from the Farm Building Plan Service, Agricultural and Biological Engineering Building, Purdue University, West Lafayette, IN 47907:

      MWPS-13, "Planning Grain-Feed Handling ($2.50)
      MWPS-22, "Low Temperature and Solar Grain Drying ($3.00)

For more information, contact Dirk Maier, Agricultural and
Biological Engineering, phone: 317-494-1175 or e-mail:
maier@ecn.purdue.edu 


New 7/80

Cooperative Extension work in Agriculture and Home Economics, State of Indiana, Purdue University and U.S. Department of Agriculture cooperating: H.A. Wadsworth, Director, West Lafayette, IN. Issued in furtherance of the acts of May 8 and June 30, 1914. The Cooperative Extension Service of Purdue University is an equal opportunity/equal access institution.