Oldham MX 52, Commissioning, Operating And Maintenance Manual

Page: 47 / 96

47
REMARK
The authorized wind speed is increased to 4.1 m/s when the detector is fitted with a weather
protective device.

Prepare the measuring channel for calibration:
- Open and swivel the front panel of the MX52 unit.
- Manually set the channel to be calculated using keys + and - on the MX52 keypad (item
D, Fig. 26).
- Press the CALIBRATION key (item C, Fig. 26).
- At the bottom right-hand side of the display panel, the letter C flashes and the yellow
LED for the relevant channel flashes, indicating that the measuring channel is in the
“CALIBRATION” position.
REMARK
When a measuring channel is in the CALIBRATION position, all the alarm relays are inhibited (in
order to avoid interfering with the slaving control networks) and the corresponding current output is
maintained at 2 mA.
- Turn the sensitivity potentiometer (item A, Fig. 27) five times in the clockwise direction
(using a screwdriver).
- Adjust the DETECTOR ZERO.
NOTE
If the ambient air is not pure, inject air using a “synthetic air” cylinder and the gas injection pipe or
a remote calibrating fixed device with a flow rate of 60 litres per hour for 25 seconds directly on the
detector or a flow rate of 170 litres per hour for 1 min 45 s using a remote calibrating fixed device.
As soon as the signal is stable on the MX52 display panel, adjust the “MEASUREMENT ZERO”
by adjusting the ZERO potentiometer (item A, Fig. 27) and corresponding to channel to be set up,
so as to read ZERO on the MX52 display panel.

Adjust the detector sensitivity:
- Inject the calibration gas using the gas injection pipe (or a remote calibrating fixed
device) in the same conditions as those applicable for the synthetic air (zero adjustment).
When the measurement has stabilized, set the value corresponding to the reference gas
concentration on the display panel of the MX52 unit by adjusting the sensitivity potentiometer for
the relevant channel (item A, Fig. 27).