Fig. 2-Drawing showing the placement of the thermocouple and "dam" in the dryer discharge chute

TM 5-3895-374-24-1 GP467FB Fig. 2-Drawing showing the placement of the thermocouple and "dam" in the dryer discharge chute. IMPORTANT A small clearance (I" maximum) should be provided under the thermocouple so material will not be trapped between the thermocouple and the chute Trapped material will cause a heat loss path and the thermocouple will give erroneous readings. The thermocouple should make good contact with the material but not be subject to severe abrasion caused by high velocities. If the material is moving so fast that it bounces and leaves air adjacent to the thermocouple, the temperature it senses will be lower than the material. It may be necessary to place a dam in the chute so that the thermocouple Is in a relatively slow moving area next to the dam. The dam must only be wide enough and high enough to create a localized area of build-up where the material loses velocity BUT DOES NOT STOP FLOWING. The thermocouple must not be located in a stagnant zone or erroneous temperature readings will result Because of the large number of variables involved, it is impossible to set down any exact size or location of the dam that will always work. Field experimentation will be necessary if good results are to be obtained. It is advisable to tack weld the dam in place so that it can be easily modified if it fails to perform satisfactorily. NOTE During normal operation, the thermocouples should be rotated once a month to expose a different area of its surface to the abrasive forces of the material. This procedure will Increase the effective life of the thermocouple. If excessive wear occurs, a protective tube may be added to shield the shaft In the region of the high velocity flow. (page 3-10)