Detcon TP-624C - Manual (Page 15)

NOTE: When switching between ranges, remember to readjust your Cal Level setting if necessary (see section 3.7.2).
Also remember to adjust your alarm setpoints if necessary (see section 3.9.1)
3.6.5 Setting Heater Voltage
The Detcon TP-624C H2S sensor is factory set for the correct heater voltage and should be ready to install without
further adjustment being required. The correct heater voltage for the sensor is 5.25 VDC when set at 25°C room
temperature. It is not normally necessary to adjust this heater voltage unless 1) the sensor is going to be used in
the remote mount format or 2) the sensor is being swapped out with a new replacement sensor.
If the user needs to adjust the heater voltage due to the above-mentioned conditions, it is necessary to make the
adjustment based on the current ambient temperature condition. Refer to the table below for guidance on proper
heater voltage set-point:
Ambient Temp Heater Voltage Set-point
25°C 5.25 VDC
35°C 5.18 VDC
45°C 5.10 VDC
55°C 5.00 VDC
15°C 5.32 VDC
5°C 5.39 VDC
-5°C 5.45 VDC
-15°C 5.50 VDC
-25°C 5.55 VDC
-40°C 5.60 VDC
3.7 C ALIBRATION
NOTE: Before calibration, verify the range setting as described in section 3.6.4.
3.7.1 Material Requirements
* Detcon PN 3270 MicroSafe™ Programming Magnet
* Detcon PN 6038 Threaded Calibration Adapter
* Span gas containing the H2S gas in air. Nitrogen mixtures are not acceptable. H2S gas concentration is recom-
mended at 25 ppm (which is the factory default for ranges 0-50 ppm and 0-100 ppm) or 10 ppm (which is the
factory default for the range 0-20 ppm) at a controlled f low rate of 200 to 500 ml/min. Other concentrations
can be used as long as they fall within allowable levels. See section 3.7.2 for details.
* Detcon PN 985-241100-321 In-Line Humidifying Tube.
NOTE: Span gas bottles contain 0% humidity and this ultra-low humidity condition will cause inaccurate readings
when used to calibrate a sensor. To prevent this error, Detcon prescribes the use of a 24” f lexible In-Line
Humidifying Tube, which adds the relative humidify to the span gas. The humidifying tube is not necessary when
using a gas generating calibration device that consists of pumped ambient air and an H2S generating source.
3.7.2 Calibration Procedure - Span
CAUTION: Verif ication of the correct calibration gas level setting and calibration span gas concentration is
required before “span” calibration. These two numbers must be equal.
Calibration consists of entering the calibration function and following the menu-displayed instructions. The display
will ask for the application of span gas in a specif ic concentration. This concentration is equal to the calibration gas
level setting. The factory default setting for span gas concentration is 10 ppm for the range 0-20 ppm and 25 ppm
for the ranges 0-50 ppm and 0-100 ppm. If a span gas containing the prescribed default concentration is not avail-
able, other concentrations may be used as long as they fall within 10% and 50% of full-scale range. However, any
alternate span gas concentration value must be programmed via the calibration gas level menu before proceeding
with span calibration. Follow the instructions below for span calibration.
Detcon Model TP-624C Hydrogen Sulfide Sensor PG.15