HALO Users Manual
Revision G
19
3.8 Pressure and Venting Considerations
Pressure considerations
Sample gas inlet pressure must be between 10-125 psig (1.7-9.6 bara) for moisture analyzers
and 30-125 psig (3.1-9.6 bara) for CH
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analyzers. At pressures below 10 psig, sufficient gas
volume may not be available to maintain the required sample flow. Pressure above 125 psig may
damage the unit’s internal pressure regulator.
Venting instructions
Wherever possible, we recommend that you vent your instrument to atmospheric pressure, but it
may also be connected to a vacuum pump. If a vent line is required, please observe the following
conditions:
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To avoid backpressure from restricted flow, the vent line must consist of ¼” tubing.
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The vent line must end in an area with no greater than atmospheric pressure.
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Care should be taken to insure that the back pressure at the sample outlet never goes above
2 psig (1.15 bara). If it is possible that the vent line could become pressurized, a low
cracking pressure check valve should be employed to prevent back flow into the sample cell.
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If you must use a vacuum pump on the outlet of the HALO, the response of a HALO is not
pressure sensitive. However, the propagation of contaminant gas is. Therefore, pressure
fluctuations will affect the measurement by altering the actual contaminant level in the sample
cell.
ATTENTION
Careful consideration should be given when venting the sample gas. Consult the
gas manufacturer with any questions on this matter.
