Introduction |
Sensortech Systems, Inc. has developed several sampling sensors for a variety of applications, of which the Air Purge Down Chute Sensor is the simplest and lowest cost.
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Description |
| The sensor comprises a rectangular horizontal tray with a vertical flange at one end. A 4" square aperture is cut out of the side of a vertical or near vertical chute (for example at the exit of a screw conveyor). The sensor flange attaches the sensor to the side of the chute with the sensor projecting inside the chute directly in the product flow. The instrument waits for a programmed "fill time" to allow the tray to reach overflow capacity. A one-second measurement period is followed by a purge period in which a solenoid actuated valve provides an air blast along the length of tray. The air blast clears the sensor tray and the instrument display holds the last measurement until next cycle completes. Sensor electrode is integrated into bottom of tray. Sensor electronics and pneumatic controls are attached to outside of sensor flange or else mounted remotely for high temperature applications. |
Continuous on-line moisture measurement is
not always possible due to inconsistent product flow. Granular materials may surge or
exhibit intermittent flow resulting in product voids. In these cases a sampling mechanism
may provide adequately frequent moisture updates in order to control a process. The
alternative may be to take samples to be tested off-line by a time consuming laboratory
method.