ANALOX 1371 MK 2 SURVEYOR CARBON DIOXIDE MONITOR
1371-810-03 User Manual, August 2007
1117
5
CALIBRATION
5.1
GENERAL COMMENTS
Calibration requires gases to be fed from cylinders of certified concentration. These gases
MUST NOT be delivered directly at cylinder pressure to the Instrument, otherwise the internal
pump will be damaged. Scottish Anglo E.P. Ltd. supply calibration kits for the 1371 Instrument,
comprising two cylinders of gas, a cylinder mounted flowmeter with control valve and suitable
tubing. It is strongly recommended that this kit is used for Calibration.
If alternative calibration equipment is used, precautions must be taken to limit the gas
pressure and flowrate to a value not exceeding 1.0 Litres per Minute.
Under no circumstances must excessive gas pressure or flow be applied to the instrument
otherwise damage to the pump and/or Transducer will be inevitable.
5.2
CALIBRATION PROCEDURE
5.2.1 Zero calibration
Using a Calibration Kit cylinder of 'Zero Gas' ie Nitrogen, fit the Flowmeter/control valve
assembly on to the Cylinder screw connector. There may be a small escape of gas just before the
assembly is fully tightened - this is quite normal. Connect the delivery tube to the small Barbed
connector on the flowmeter and then to the 'GAS IN' port on the Instrument. Adjust the rotary
valve on the flowmeter until the indicator ball is level with the middle graduation on the flowmeter.
This produces a flow of approximately 1 Litre per minute. Allow the displayed reading to stabilise
and if necessary, adjust the 'ZERO' trimmer, to the left of the display, until the Display shows
'000'.
5.2.2 Span Calibration
Using a Calibration Kit cylinder of 'Span Gas' having a concentration of CO
2
between 75% and
100% of Instrument measuring range, fit the Flowmeter/control valve as described in Section
5.2.1. Adjust the rotary valve on the flowmeter until the indicator ball is level with the middle
graduation on the flowmeter. This produces a flow of approximately 1 Litre per minute. Allow the
displayed reading to stabilise and if necessary, adjust the 'SPAN' trimmer, until the reading on
the display is the same as the concentration of the Certified gas mixture.
5.2.3 Close the control valve, remove the plastic tubing from the instrument and the flowmeter and
remove the flowmeter/control valve assembly from the gas cylinder. The control valve is not
designed to provide a total gas shut-off when closed so to conserve gas supplies, it should only be
fitted immediately before use.
