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Midland Machinery Show 2018
21st & 22nd November


LAMMA 2019
8th & 9th January



Confidence in our design,
materials and care in
manufacturing and installation
is reflected in our
10-year warranty.



FLR Crop Drying is a brand
of Flach & Le-Roy Ltd

Store Operation

How do I calculate the minimum number of air duct outlets I need to open in relation to the volume of air that my fans produce?

Answer:

  1. Assuming 8’ to 10’ storage depth the required airspeed through the crop in a grain store is 20ft/min and the fan working at 4.0”swg pressure:

i.   A 30kw fan will produce 30,000 cfm at 4.0” swg.
ii.  30,000 divided by 20 ft/min airspeed through the crop means that the fan is capable of
ventilating a floor area of 30,000/20 = 1500 sq ft.
iii. If the floor width is 30’, then the length of duct outlets which should be open is 1500 / 30
= 50’ run.
iv. If the duct outlets are every 16” then 50 x 12 / 16 = 37 outlets open. 

  1. Assuming 12’ storage depth the required airspeed through the crop is 24ft/min and the fan working at 6.0” swg pressure.

i.  A 30kw fan will produce 26,000 cfm at 6.0” swg.
ii. 26,000 divided by 24 ft/min airspeed through the crop means that the fan is capable of
ventilating a floor area of 26,000/24 = 1080 sq ft.
iii. If the floor width is 30’, then the length of duct outlets which should be open is 1080 / 30
= 36’ run.
iv. If the duct outlets are every 16” then 36 x 12 / 16 = 27 outlets open.