Ion Science TVOC - Manual (Page 25)

TVOC MANUAL Ion Science Ltd
Page 25 of 32
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System recommendations
For a gas sample system we have the following recommendations:
1. Where possible use the Flow Adaptor (as described above) that is sold by ISL. This has an integral
o-ring to seal the sensor housing and ports for connection of inlet and out let sample tubes. Please refer
to Spare parts section for part number.
2. The pressure difference of a pumped system relative to atmosphere should be minimised to avoid the
effects of gas law.
3. The maximum pressure that can be applied to the TVOC sensor housing is 300 mbar. However this is
not a recommended working pressure. Ideally working pressure should be +/- 30 mBar relative to
ambient pressure.
4. In line flow restrictions must be minimized. Flow restrictions cause differential pressures which can
directly affect the TVOC ready. If flow restrictions are unavoidable the flow rate should be lowered to
minimize the pressure effects, this however will increase the response time.
5. A flow between 250 and 500 ml/min is recommended for calibration. This will ensure a full response to
applied gas in a sensible time.
6. The working flow should be very similar to that use to calibrate the instrument or errors in output will
occur (see point 2).
7. The response time of the system is defined by the sensor response rate and sample flow rate will in
combination with the tube length and diameter as well as any dead volumes.