Industrial Scientific OLDHAM 300 Series, Operating And Maintenance Manual

Page: 16 / 49

17
Now inject the recommended test gas at a flow rate of 30 l/h (use the calibration kit and follow all
recommendations)
Wait until the signal has stabilized, read the mV value on the voltmeter (Fig. 13, rep 1), with the full
scale at 1600 mV, calculate the value to be read as a function of your test gas. Adjust using the
potentiometer (Fig. 14, rep 2).
Example: CO sensor scale 0-300 ppm / test gas injected at a content of 100ppm
Reading
533 mV
Shut off the calibration gas injection and withdraw the gas injection pipe. Then wait and check that
the scale has returned to zero (otherwise repeat the procedure).
Switch the maintenance on/off switch to the “MES” (measure) position (rep 5, Fig. 3)
1.4. COX 300 Calibration, “OXYGEN” type
COX 300 “oxygen” with display screen.
See paragraph 1 – 3 (Method 1). Proceed with adjusting sensitivity ONLY by injection of test gas.
COX 300 “oxygen” without display screen or diodes (DEL)
See paragraph 1 – 3.( Method 2). Proceed ONLY with sensitiv ity adjustment.
Signal value in mV =
- 1600 mV for full scale = 30% O
2
- 1115 mV for 20.9 % O
2
- 0 mV for 0% O
2
Notes:
The signal sent from the CTX/COX 300 (toxic or oxygen) sensor to the central controller can be
measured on the main circuit by connecting a millivoltmeter to the pins designed for this purpose
(Fig. 16).
-
400 mVCC

4 mA
-
2 VCC

20 mA
-
V
+ Circuit principal du capteur
Fig. 16