Maintenance; Calibration; Sintered Metal Filter Replacement; Sensing Head Replacement - DALEMANS DAT 420 Instruction Manual

4.

MAINTENANCE

4.1.

Calibration

Gas detectors must be calibrated at least once a year to mitigate the possible loss of sensitivity of
the sensor. This calibration must be performed according to the procedure given by DALEMANS
or his local representative, and in any case by qualified personnel who will have received a suita-
ble training.
4.2.

Sintered metal filter replacement

If contamination of the sintered metal filter by solvent, gas or vapour has occurred, the sensing
head must be replaced and the inspection frequency should be increased twofold.
▪ Unscrew the sensing head top using the suitable tool OUT00000113.
▪ Replace the sinter metal filter with a new one MEC00000010.
▪ Screw the sensing head top back on again and tighten.
▪ Make sure the sensing head is still correctly fastened to the junction box.
▪ Perform calibration according to the procedure given by DALEMANS or his representative.
4.3.

Sensing head replacement

Loosen the locking screw of the junction box cover using the 1.5 mm hex key.
▪
▪ Completely turn the cover counterclockwise to unscrew it.
▪ On the terminal block, disconnect the two wires of the sensing head and remove the ferrite.
Unscrew the sensing head using the tool OUT00000114 placed between the base and the
▪
junction box.
▪ Screw the new sensing head back on again and tighten.
▪ Put the ferrite on the wires and reconnect them to the terminal block (see
▪
▪
▪ Screw the cover back onto the junction box and hand tighten ¼ turn.
▪ Put the locking screw of the cover back in place and tighten with the 1.5 mm hex key.
▪ Power on the detector and restore its safety function on the control unit or the PLC.
▪ Perform calibration according to the procedure given by DALEMANS or his representative.
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Prior to carrying out maintenance or service operations on the gas detector,
inhibit the safety function of the detector on the associated control unit or PLC
and secure any output device connected to the system to prevent false alarms
and unintended actuations.
Never open the detector when flammable gas is present.
Regularly remove dust from the detector WITH A DAMP CLOTH ONLY to avoid
the risk of electrostatic sparks.
RED wire on terminal +
BLUE wire on terminal -
Figure 2):
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