Detcon 1000 - Manual (Page 25)

Mdl 1000 H2S E-Chem / Inst. Air
Model 1000 H2S E-Chem w Instrument Air Rev. 1.1 Page 21 of 28
10. Display Contrast Adjustment
Detcon MicroSafe™ sensors feature a 16 character backlit liquid crystal display. Like most LCDs, character
contrast can be affected by viewing angle and temperature. Temperature compensation circuitry included in
the MicroSafe™ design will compensate for this characteristic; however temperature extremes may still cause
a shift in the contrast. Display contrast can be adjusted by the user if necessary. However, changing the
contrast requires that the sensor housing be opened, thus declassification of the area is required.
To adjust the display contrast, remove the enclosure cover and use a jeweler’s screwdriver to turn the contrast
adjust screw located beneath the metallic face plate. The adjustment location is marked “CONTRAST”.
11. Low Flow Fault Options
Model 1000 Analyzers offer two low flow fault option PCB’s. One monitors for low sample gas flow, and the
second monitors for low airflow dilution. The Low Flow Fault option for sample gas flow is usually set for
the relay contacts to fire at flow rates ≤ 100cc/min. The Flow Fault option for air dilution is usually set for the
relay contacts to fire at flow rates ≤ 300cc/min. These set points are factory set. Should it become necessary
to adjust the flow fault set points in the field, adjust the flow to the set point target (100 or 300cc/min.) at
Rotameter(s) and adjust the potentiometer on the corresponding Low Flow Fault PCB until the fault LED
toggles between “ON” and “OFF”.
12. Sensor Replacement
Should the electrochemical H
2
S plug-in sensor (part number 370-323200-000) require replacement, use the
following procedure:
1 - (A) If the sensor is mounted in a classified area, system power to the transmitter must first be removed
before proceeding further.
(B) If in an unclassified area, remove front enclosure cover and unplug transmitter module.
2 - Remove gas flow adapter and tubing connections to expose sensor housing.
3 - Unscrew the three screws of the sensor head bottom.
4 - Pull the sensor head bottom down and off.
5 - Grasp the electrochemical sensor cell and unplug by pulling down.
6 - Plug in the new sensor. Replace the sensor head bottom and screw in place.
7 - Re-attach gas inlet adapter and tubing connections.
8 - Restore system power (if classified) or plug in transmitter module and replace enclosure cover (if
unclassified).
9 - Perform a new zero and span calibration after 1-2 hours of warm-up time.