Detcon DM-434B - Manual (Page 5)

2.0 PRINCIPLE OF OPERATION
Method of detection is by a controlled rate of diffusion. Air and gas diffuse through a sintered stainless
steel filter and a diffusion barrier. As oxygen is adsorbed into the electrolyte solution a current is generat-
ed between the cathode and anode electrodes. This current output rises with increases in oxygen concen-
tration and reverses with lower concentrations. The quick response of the cell results in continuous moni-
toring of ambient air conditions.
3.0 APPLICATION
Model DM-434B sensors are designed to detect and monitor oxygen deficiency in ambient air in the range of
0-25%. Operating temperature range is -4° F. to +122° F. While the sensor is capable of operating outside
these temperatures, performance specifications are verified within the limit.
3.1 Sensor Placement/Mounting
Sensor location should be reviewed by facility engineering and safety personnel. Area leak sources and
perimeter mounting are typically used to determine number and location of sensors. The sensors are gen-
erally located 2 - 4 feet above grade.
3.2 Interference Data
Methane
100% = 0
Hydrocarbons 100% = 0
Hydrogen 100% = < -2%
Carbon Monoxide 20% = < -0.5%
4.0 SPECIFICATIONS
Method of Detection
Air battery diffusion/adsorption
Measurement Range
0-25% O2
Accuracy/Repeatability
± 2% FS
± 2% FS
Response /Clearing Time
T90 < 20 seconds; T90 < 20 seconds
Zero Drift
< 2% per month
Operating Temperature Range
-4° to +122° F; -20°C to +50°C
Operating Humidity Range
0-99% RH (non-condensing)
Detcon Model DM-434B Oxygen Sensor PG.5
FUNCTIONAL BLOCK DIAGRAM
PRE-AMP
SIGNAL
CONDITIONING
(ZERO/SPAN)
XMTR
POWER
SUPPLY
I/O CIRCUIT
PROTECTION
SIGNAL OUT
POWER IN
SENSOR