When do we get condensation, dripping and crusting in the bin?

The grain drying calculator gives the precise conditions under which condensation will occur; and that is whenever RHthres is greater than 100. (See the blog on dripping).  In playing around with the calculator today, I can give you a rule of thumb for this without using the calculator.

For oilseeds like canola and flax, that is just dry 10% MC; if the grain is more than 5 deg C warmer than the outside air (roof), there will be condensation.  I tried the calculator with GrainTemp – AirTemp,  30 – 25,  20 -15, 10 -5.  So a difference of 5 C gave me an RHthres close to 100%.

For cereals like wheat and barley, that is just dry at 14.5% MC; if the grain is more than 7 deg C warmer than the outside air (roof  & walls) , you have conditions for condensation.  Tried 27 – 20,  17 – 10, 7  – 0 and they gave RHthres close to 100.

This is interesting, because we see that oilseeds are more sensitive to condensation, and we certainly don’t need much of a difference in temperature before condensation starts to form on the top layer of grain and the inside of the roof —  only 5 deg C  difference!!  For example, if you have wheat that is 28 C and the outside temp is 20 C, you could turn on the fan and you are in for a bit of condensation on the inside of your roof, and on the top layer of wheat.

For years and years we have had spoilage from condensation because we did not turn the fans on immediately to cool the grain with a temperature that was close to the actual temperature of the grain?

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