GasCheck
Operating Manual V2.4
12
5.
SERVICE AND MAINTENANCE
A full after sales calibration and service facility is provided by Edinburgh
Instruments. Service parts and equipment are also available.
5.1
Calibration
Edinburgh Instruments products are inherently stable and will maintain their
calibration over extended periods with minimal maintenance. We recommend
that the calibration of the GasCheck is checked at least once a year. Any
adjustments should be small.
ZERO (nitrogen) and SPAN calibration gases must be applied to the sensor in
order to check its calibration. To supply gas from a pressurized bottle a
pressure regulator, a needle valve, a gas flow meter and an inlet pipe are
needed. When supplying gas the following conditions should be maintained:
the CO
2
concentration of the SPAN gas should be between 80 and
105 % of the full scale
the tolerance of the CO
2
volume concentration of the gas bottle
should be 2% or better
the output pressure from the regulator should only slightly exceed the
ambient pressure
CAUTION
Never connect cylinders or other pressure sources
directly to the sensor as the high pressure in the
cylinder may damage the sensor unit.
Gas may be safely connected to the instrument by providing excess flow and
venting off the excess gas through an open T-piece with a 1 m pipe connected
to it. The procedure for checking/adjusting the calibration is as follows:
1. Any adjustments are made using the ZERO and SPAN adjust
potentiometers on the detector printed board (the printed board on the
sensor head, see Figure 4.1).
Note:
on the linearised version the offset and gain potentiometers
VR1 and VR2 on the main PCB are for adjusting out electrical
tolerances and should not be used.
