22 November 2001
Grain 2001: Vertical ventilation can work
By FARMERS WEEKLY staff
VERTICAL ventilation can work well to cool grain and avoid insect damage and contamination, Home-Grown Cereals Authority work confirms.
But be sure to remember storage depth when positioning ducts, advises ADASs David Bartlett.
“Our work confirms that rule of thumb established practice for 3m works in most situations, which is comforting. But it may not work so well if you store deeper.
Ducts effective 6.3m (21ft) apart when grain is typically stored at 3m should be no more than 4.4m (14ft) from each other if the depth doubles, he warns.
Equipment for the job costs less than conventional horizontal systems, and both sucking and blowing systems can be effective, he says.
But they need to be planned and managed carefully.
Ideally time switches or differential thermostats should be incorporated so only air that is cooler than the grain is blown.
The aim should be to get grain temperature down to 15C within two weeks, the latest HGCA topic sheet No 53 Vertical ventilation for cooling grain explains.
Growers should then keep cooling so that the bulk reaches 10C within six weeks.
Using vertical ventilation probes to cure hot spots has long been accepted, says Martin Lishman who began supplying suitable equipment 26 years ago.
But the realisation that it can be used for overall cooling and even drying has only caught on in the past five or six years.
“The reason is basically local recommendation that it works.
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