Subject: Ref #178                              Dated: 9/7/99



TO:       	FGIS POLICY BULLETIN BOARD	       9/7/99

FROM:     	David Orr, Director
                Field Management Division

SUBJECT:  	Moisture Samples – Rapid Cooling Procedures

ORIGINATING OFFICE:	  Weighing & Equipment Branch


BACKGROUND:  The Moisture Handbook, page 3-6, outlines a quick 
warm-up procedure for very cold samples.  It recommends use of a 
small sample placed in a 1-gallon, zipper-closure plastic bag, a 
wire rack, and fan.  This procedure can warm a sample to room 
temperature in a few minutes.

The Technical Services Division has conducted several tests to 
determine if the Moisture Handbook procedures for warming cold 
grain samples can also be utilized for cooling samples that are 
very hot (110 degrees F).

POLICY:  The same procedure as used for rapid warming of very cold 
samples can be used for rapid cooling of very warm samples that 
are relatively dry (less than 14 percent moisture content).  The 
procedure will cool grain from 110 degrees F to below 90 degrees F 
in three minutes if the room temperature is about 70 degrees F.  

Caution:  The method is not recommended for grain that is above 14 
percent moisture content, because moisture may condense on the 
inner surface of the plastic bag, wet the grain surface, and cause 
erratic moisture readings.  If droplets of water are visible on 
the inner surface of the bag after cooling, the sample is too wet 
for reliable cooling using this quick method.  Also, this rapid 
cooling method does not ensure accurate readings for grain that 
has moisture gradients within the kernels due to high temperature 
drying.  

Use of quick warm-up or cool-down procedures is optional.  Normal 
temperature equilibration procedures can be followed in most 
cases.  Normal procedures allow samples to equilibrate over a 
longer period of time, while placed in moisture-proof containers 
such as metal cans, plastic bottles, etc..

Please distribute this policy memo to official agencies in your 
circuit.  This policy is effective upon receipt.