RKI Instruments GD-K8A - Manual (Page 14)

10 • Model GD-K8A Diffusion Detector Head
Slow or No Response/Difficult or Unable to Calibrate
Symptoms
• The GD-K8A responds slowly or does not respond during the monthly response test.
• Unable to accurately set the zero or response reading during the calibration
procedure.
• The GD-K8A requires frequent calibration.
NOTE: Under “normal” circumstances, the GD-K8A requires calibration every 3 - 6
months. Some applications may require a more frequent calibration schedule.
Probable causes
• The calibration cylinder is low, out-dated, or defective.
• The GD-K8A is malfunctioning.
Recommended action
1. Verify that the calibration cylinder contains an adequate supply of a fresh test sample.
2. If the calibration/response difficulties continue, replace the sensor.
3. If the calibration/response difficulties continue, contact RKI Instruments, Inc. for
further instruction.
Storing the GD-K8A
The GD-K8A’s ASK keeps a bias voltage on the sensor whenever there is no incoming
power, such as during shipment, storage, or power outages. This circuit is powered by the
alkaline batteries. If the batteries are dead when power to the GD-K8A is turned off or is
lost, then the bias voltage normally on the sensor during operation will not be applied to
the sensor. If the sensor is without the bias voltage for an extended period, it will take
some time to stabilize and be ready for use after power is restored. If the sensor is off bias
for too long, it may not be usable when power is restored.
When starting with a full charge, the alkaline batteries will last approximately 8 months.
Be sure to replace the batteries periodically to assure that the sensor will always be on bias
during power outages.
If the GD-K8A is going to be stored, make sure fresh batteries are installed to maintain a
bias on the sensor. See the next section for instructions to change the batteries.
In addition to keeping the sensor on bias during storage, the GD-K8A must be kept
upright. If the GD-K8A is stored, it must be oriented so that the sensor is upright.
WARNING: If the GD-K8A is not stored in an upright position, the sensor membrane
which allows gas into the sensor may dry out and the sensor may not
recover proper operation.
Replacing Components of the GD-K8A
Replacing the Sensor
1. Turn off the controller.
2. Turn off power to the controller.
3. Open the GD-K8A’s housing door.