1072_B
6
June 2020
Bulk Material Testing
The dryness of bulk material such as plastic resin, raw materials, or food
products can be inferred from the dew point of air within the storage
container.
Depending on the shape of material and size of storage container, it may be
helpful to use a short length of metal tubing or Hygrodynamic’s sampling wand
to probe into the material. Ideally, you want to sample air near the center of
the container, surrounded by the material to be tested. Avoid testing powdery
or very fine products which may clog the 1072’s sampling system. Product in
granular form is recommended.
Plastics Molding Applications
Model 1072A is commonly used in the plastics molding industry to check for
proper dryer function. To enable testing of your process air, you should provide
fittings in your drying system that will accept the 1072A’s 3/16” ID sample
tubing. This can be a barbed hose fitting or a piece of ¼” copper tube that
penetrates your dryer’s air hoses. The point of attachment must be secure and
leak-free.
The flexible sample tubing supplied with the hygrometer can tolerate
temperatures up to 275
F (135
C). Higher process air temperatures can be
cooled to a safe level by sampling through a few feet of ¼” copper tubing.
Select the sample locations based on your testing needs (refer to diagram
below). It is suggested that you have permanently accessible sample points at
both the dryer output and return hoses. If your dryer has threaded test ports
on the inlet and outlet connections (typically for thermocouples) use these to
make points of connection. Some dryer manufacturers provide a port for
sampling.