Detcon TP-700 - Manual (Page 15)

Model TP-700
TP-700 Instruction Manual Rev. 3.5 Page 11 of 38
a) TP-700 display reads “0”, and no fault messages are flashing.
b) A temporary upscale reading may occur as the sensor heats up. This upscale reading will decrease to “0”
ppm within 1-2 minutes of power-up, assuming there is no gas in the area of the sensor.
NOTE: A desiccant cap with a desiccant packet is attached to the sensor cell housing to avoid
damage during storage and shipping. This prevents water from contacting the sensor film, and
as a result helps to retain the stability of the factory span calibration.
c) Remove the desiccant cap about 10 minutes after applying power to the sensor and install the
weatherproof splashguard accessory supplied with the sensor.
NOTE: Store the desiccant caps with the desiccant packets in a sealed container (i.e. zip-lock
bag) for future use. It is advisable (but not mandatory) to reinstall the desiccant cap and packet
during prolonged periods without power (more than 1 day is considered “prolonged”). An
active desiccant packet is blue in color and turns pink when consumed. (P/N 960-240010-000)
NOTE: The 4-20mA signal is held constant at 4mA for the first two minutes after power up.
2.7.1 Initial Operational Tests
After a warm up period of 1 hour, the sensor should be checked to verify sensitivity to H
2
S gas.
Material Requirements
 Detcon PN 613-120000-700 700 Series Splash Guard with integral Cal Port -OR-
 Detcon PN 943-000006-132 Threaded Calibration Adapter
 Detcon PN 942-010112-025 Span Gas; 25ppm H
2
S in balance Air at fixed flow rate between 200 -
500cc/min (10ppm for 0-20ppm range)
 Detcon PN 985-241100-321 In-Line Humidifying Tube
NOTE: Do not use H
2
S in Nitrogen background gas mixtures. This will cause significant
reading inaccuracies.
a) Connect the In-Line Humidifying Tube between the cal gas cylinder and the sensor. The humidifying tube
will introduce the ambient relative humidity into the Cal Gas as it passes through the tube.
b) Attach the calibration adapter to the threaded sensor housing. Apply the test gas at a controlled flow rate
of 200 - 500cc/min (200cc/min is the recommended flow). Allow 1-2 minutes for the reading to stabilize.
Observe that during the 1-2 minutes the ITM display increases to a level near that of the applied
calibration gas value.
c) Remove test gas and observe that the ITM display decreases to “0”.
Initial operational tests are complete. Detcon H
2
S gas sensors are factory calibrated prior to shipment, and
should not require significant adjustment on start up. However, it is recommended that a complete calibration
test and adjustment be performed 16 to 24 hours after power-up. Refer to span calibration instructions in
Section 3.4.