DM-634C Oxygen Sensor Assembly
DM-634C O2 Sensor Instruction Manual Rev. .066
Page 1 of 25
3.0
Description
Detcon MicroSafe™ Model DM-634, oxygen deficiency sensors are non-intrusive “Smart” sensors designed
to detect and monitor O2 in air over the range of 0-25%. One of the primary features of the sensor is its
method of automatic calibration which guides the user through each step via instructions displayed on the
backlit LCD. The sensor features field adjustable, fully programmable alarms and provides relays for two
alarms plus fault as standard. The sensor come with two different outputs: analog 4-20 mA, and serial RS-
485. These outputs allow for greater flexibility in the system integration and installation. The microprocessor-
supervised electronics are packaged as a plug-in module that mates to a standard connector board. Both are
housed in an explosion proof condulet that includes a glass lens window which allows for the display of the
sensor readings as well as access to the sensor’s menu driven features via a hand-held programming magnet.
3.0.1
Sensor Technology
The sensor technology is of the two electrode, galvanic metal air battery type cell, which is housed as a field
replaceable plug–in module. The cell is diffusion limited and functions as a direct current generator
proportional to the amount of oxygen adsorption. The sensors are temperature compensated and show good
accuracy and stability over the operating temperature range -4° to +122° Fahrenheit. The sensor is warranted
for two year and has an expected service life of up to two years in ambient air at 20.9% oxygen.
Figure 1
Construction of Galvanic Cell
