9
3
Maintenance
The operations and adjustments described in this chapter must be performed
by authorized personnel only as they can affect the appliance's reliability in
detection.
It is prohibited to open the transmitter when energized
3.1
Detector OLC 20
Gas detection instruments are potential life-saving devices. Recognizing this fact, OLDHAM Corporation
recommends that a functional “bump” test be performed on every fixed gas-monitoring instruments as part of
a regular maintenance program. A functional test is defined as a brief exposure of the detector to a
concentration of gas(es) in excess of the lowest alarm set-point for each sensor for the purpose of verifying
sensor and alarm operation and is not intended to be a measure of the accuracy of the instrument.
OLDHAM further recommends that a full instrument calibration be performed using a certified
concentration(s) of calibration gas(es) quarterly, every 3 months.* Calibrations may be necessary more or
less frequently based, for example, on application, field conditions, exposure to gas, sensor technology, and
environmental conditions. The frequency of calibration is best determined by company policy or local
regulatory agencies.
If an instrument fails to operate properly during any functional “bump” test, a full instrument calibration
should be performed successfully prior to use.
These recommendations are based on safe work procedures, industry best practises, and regulatory standards
to ensure worker safety. OLDHAM is not responsible for setting safety practices and policies.
*
For new installations it may be prudent to carry out bump tests frequently at first (perhaps weekly),
increasing the time intervals (to, perhaps, monthly or more) as confidence grows with experience in the
installation concerned, on the basis of the maintenance record.
3.1.1
Calibration
On the controller
On the detector
Set the measuring channel to the calibration
position (alarm relays inhibited)
Proceed the zero and span
Set the measuring channel back to the
"normal" position and make sure that it is
working properly.
Apply the calibration cup and perform the
calibration in accordance with the procedure
defined during the training course provided
by OLDHAM or by an OLDHAM’s
authorized person
