Sierra Monitor Corporation 4501-05 - Manual (Page 28)

Model 4501-XX Toxic Gas Sensor Module
Page 24 of 35
8.4 APPENDIX D: 4501-25 & 4501-26 GAS SENSOR MODULE
1. Calibration of 4501-26 (Follow instructions in Section 6)
2. Calibration of 4501-25 (See below)
3. Equipment Required
The following tools and equipment will be required for calibration:
- Permeation Device Calibrator (Model 9210-00), with
Ammonia Permeation Tube (Model 9211-09).
- Calibration Adapter (Model 5358-01).
4. Permeation Device Calibrator Operation
The calibrator is a portable device with a pump that operates from a 1.5 V
alkaline size D battery. A fresh battery should allow 8 hours of continuous
operation. The permeation device will probably be shipped separately,
usually in a pipe with screw cap ends, one of which will be marked for
opening. The permeation device should come fitted with a scrubber, but, as a
precaution, open the pipe and remove the permeation device in a
well ventilated area.
1. Remove the scrubber from the permeation device and attach the device
to the stainless steel “Tee” assembly inside the calibrator box. Tighten
the connection with a wrench, with the device resting inside one of the
openings in the rack.
2. Close the door of the calibrator and turn on the pump switch.
3. Set the flow rate for the desired ppm of ammonia. The desired flow rate for calibration of the Model
4501-25 is 300-500 cc/min. and the concentration range should be set between the high alarm point and
100 ppm full scale.
The carrier gas flow rate can be calculated from the formula:
P = (CxF)/K
Where P = the permeation rate in nanograms/min., and C = ppm of span gas, F = carrier gas flow rate in
ml./min. and K = 1.437 for ammonia. The permeation rate for the temperature read on the front of the
calibrator can be obtained from permeation rate vs. temperature chart.
4. Run the gas calibrator for 30 min. before attaching the output hose to the ammonia sensor.
5. When the use of the calibrator is completed, do not turn off the pump unit until the permeation device
has been removed from the “Tee” and the gas scrubber reattached. Failure to remove the permeation
device when the pump has been turned off will contaminate the system with high amounts of the
permeating gas and result in erroneous concentrations. The device, with scrubber, can be stored in the
storage rack overnight, but should not stay in the gas calibrator for longer storage periods.
5. Calibration Procedure
Follow procedures outlined in Section 6.0
Figure 8 - 1: Module
Components