Gas Installation - Systech Instruments EC900 series Operator's Instruction Manual

EC900 Series Operation Manual
V4.7

7.2 Gas Installation

The instrument can be used to measure different oxygen concentrations. If the application is the
measurement of percent oxygen, then the instrument may be connected with plastic/nylon/ptfe tubing
otherwise all fittings and sample lines to the instrument should be high integrity so ensuring no
ambient air is allowed to leak into the system.
It is recommended that stainless steel or copper lines be used for the sample inlet.
If a vent line (sample outlet) is fitted then this may be of nylon tubing or similar, but should be
installed so that no back pressure may build up due to a restricted outlet.
The inlet and outlet pipe size is 1/8 inch compression (standard).
The two valves on the gas chassis serve to seal off the instrument from the sample and the sample
inlet valve will also serve as a flow regulator valve.
When a pressurised supply of sample gas has been connected to the instrument, the cell outlet valve
should be opened fully, and then the sample inlet valve should be opened sufficiently to obtain a
desirable flow: approximately 100 - 150ml/min will be adequate.
For analyzers fitted with the pump option, the cell inlet valve should be opened fully and the cell outlet
valve opened sufficiently to obtain 100 - 150 ml/min.
Too high a flow rate will pressurise the measuring cell and cause an error in the reading for some
time.
Conversely, the instrument should be disconnected from the sample by reversing the above
procedures. In other words at no time should the cell be pressurised with the sample inlet pressure,
or by the pump. Failure to follow this procedure may result in irreparable damage to the cell.
NOTE: Instruments fitted with a RACE cell only have one sample isolation valve.
Important
EC9x1 EC9x2
Sample lines and upstream pressure regulators should be thoroughly purged before connecting to
the analyzer. If a bypass flowmeter and adjustment valve has been fitted to the instrument, then the
purging can be achieved easily before the isolation valves are opened.
Pressure Regulation
There is no need to regulate the pressure upstream from the analyzer unless it is either above 29psi
(2 Bar) or can fluctuate wildly, thereby changing the flow through the instrument. If one is measuring
low ppm oxygen and a pressure regulator is necessary, then only a high quality regulator will suffice
(see spare parts.)
If however, the pressure of the sample gas is below 3.5psi (0.25 Bar) and is not enough to pass a
sample through the analyzer, then a pump will be required and the same comments are applicable as
above. Consult Systech / Illinois Instruments for advice.
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