Is it possible for Low Volume cooling fans (not drying fans) to add moisture to dried grain & OSR stored in silos? I have been given conflicting answers from different people who should know what they are on about... If so, how much moisture could be added during cooling after leaving the drier? I seem to be torn between the need to reduce temperatures as quickly as possible, without adding moisture. Should silo fans be used on nights when it is raining? If blowing is restricted to dry nights, the opportunities for cooling are reduced and so cooling would take much longer.

 Simple answer is yes. It all depends on the moisture content of the grain and the relative humidity of the air.

 

Simple answer is yes - Paw is basically right, the grains will be in equilibrium with the RH of the air passing through.

 In reality, it is actually easier to dry than it is to re-wet. Low volume fans might dampen the bottom layer on a foggy night which can cause serious problems at the bottom but mostly you won't cause much harm.

Cold air holds less moisture, hence why you don't get fog or mist on a warm day & why on-floor high volume fans dry less effectively as you get closer to the winter. One day of fan operation in August is worth 3 days in November in terms of drying capacity for the same realtive humidity.

In my experience moisture tends to drop by up to 0.5% when you take about 10oC out of the bulk anyway, so don't worry about the moisture rising if you cool your silo. Are you actually trying to add moisture or are you just storing at the threshold of sale i.e. 15% for wheat/barley or 9% in osr/linseed?

There's a plethora of stuff about this on the internet, especially if you look at some of the the US & Canadian pages via a Google search. I did plenty of homework on drying using on floor stores & relative humidity controllers when I started my previous job, having only ever used high temperature dryers then low volume cooling systems.

Brisel:

 Low volume fans might dampen the bottom layer on a foggy night which can cause serious problems at the bottom but mostly you won't cause much harm.

In my experience moisture tends to drop by up to 0.5% when you take about 10oC out of the bulk anyway, so don't worry about the moisture rising if you cool your silo. Are you actually trying to add moisture or are you just storing at the threshold of sale i.e. 15% for wheat/barley or 9% in osr/linseed?

 Many thanks for your help.

We dry in a continuous flow drier before storage. We would not run fans on a foggy night, but are undecided about nights with rain.

 Slightly dampening the bottom layer is not a problem because we recirculate each silo thoroughly once cooled below 10c.

We dry according to contract spec., so 13.5 - 14.5% for malting/milling, below 15% for feed and below 9% for OSR.