Detcon DM-634 - Manual (Page 3)

3.0 D ESCRIPTION
Detcon MicroSafe™ Model DM-634, oxygen def iciency 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 f ield adjustable, fully programmable alarms and provides relays for two alarms plus fault as standard.
The sensor comes with two different outputs: analog 4-20 mA, and serial RS-485. These outputs allow for greater
f lexibility in 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 sensor readings as well as access to the sensor’s menu driven fea-
tures 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 f ield
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
Detcon Model DM-634 Oxygen Sensor PG.3
Construction of Galvanic Cell
Cathode
Anode
Electrolyte
Solution
Diffusion Barrier
Air Supply
Load
Resistor