Detcon DM-634 User Manual
Page 7
* The estimated remaining sensor life. The menu item appears as:
“SENSOR LIFE 100%”
3.4.3.2 Alarm 1 Level Adjustment
The alarm 1 level is adjustable from 2.5% to 22.5%. The menu item appears as:
“SET ALM1 @ 19.5%”
3.4.3.3 Alarm 2 Level Adjustment
The alarm 2 level is adjustable from 2.5% to 22.5%. The menu item appears as:
“SET ALM2 @ 17.5%”
3.4.3.4 Calibration Level Adjustment
The calibration level is adjustable from 15.0% to 25.0% O2. The menu item appears as:
“CalLevel @ xx.x%”
3.5 I
NSTALLATION
Optimum performance of ambient air/gas sensor devices is directly relative to proper location and installation practice.
3.5.1 Field Wiring Table (4-20 mA output)
Detcon MicroSafe™ O2 sensor assemblies require three conductor connection between power supplies and host
electronic controllers. Wiring designators are + (DC), – (DC) , and mA (sensor signal). Maximum single conductor
resistance between sensor and controller is 10 ohms. Maximum wire size for termination in the sensor assembly ter-
minal board is 14 gauge.
AWG
Meters
Feet
20
240
800
18
360
1200
16
600
2000
14
900
3000
Note 1: This wiring table is based on stranded tinned copper wire and is designed to serve as a reference only.
Note 2: Shielded cable may be required in installations where cable trays or conduit runs include high voltage
lines or other sources of induced interference.
The RS-485 (if applicable) requires 24 gauge, two conductor, shielded, twisted pair cable between sensor and host
PC. Use Belden part number 9841. Two sets of terminals are located on the connector board to facilitate serial loop
wiring from sensor to sensor. Wiring designators are A & B (IN) and A & B (OUT).
3.5.2 Sensor Location
Selection of sensor location is critical to the overall safe performance of the product. Five factors play an important
role in selection of sensor locations:
(1) Density of the gas to be detected
(2) Most probable leak sources within the industrial process
(3) Ventilation or prevailing wind conditions
(4) Personnel exposure
(5) Accessibility for routine maintenance
Density - Placement of sensors relative to the density of the target gas is such that sensors for the detection of
heavier than air gases should be located within 2-4 feet of grade as these heavy gases will tend to settle in low lying
areas. For gases lighter than air, sensor placement should be 4-8 feet above grade in open areas or in pitched areas
of enclosed spaces.
Leak Sources - Most probable leak sources within an industrial process include f langes, valves, and tubing connec-
tions of the sealed type where seals may either fail or wear. Other leak sources are best determined by facility engi-
neers with experience in similar processes.
Detcon Model DM-634 Oxygen Sensor PG.7