GE Analytical Instruments ©2006 15-14 DLM 14291 Rev. A
Set the NOA to the Stop mode and wait until the purging cycle is finished and the
pump is off. Use a 7/16” wrench to remove the restrictor from the sample inlet of
the NOA back panel. Use a squeeze bottle to fill the metal tubing on the NOA’s
side of the restrictor with water, then connect the 1/8” nut to a high-pressure gas
source. Turn on the gas the force the water back through the frit. Repeat this
several times to backflush the frit with water and retest the flow.
If backflushing with water does not remove the clog and an ultrasonic cleaner is
available, place the restrictor in the ultrasonic bath using water or a detergent
and sonicate for 10-15 minutes to dislodge any particles that may be blocking the
frit. Rinse the restrictor thoroughly with deionized water. Connect the restrictor
to a high pressure gas supply and backflush the restrictor with high pressure gas to
remove any water and particles that remain in the restrictor. Reconnect the
restrictor to the NOA and repeat the flow check. In some cases, sonication will not
remove the blockage and the restrictor will have to be replaced.
Gas Sampling Particle Filter
The filter in the gas-sampling package will get clogged over time and needs to be
replaced. The filter should be replaced when it becomes visibly dirty or wet. The
cell pressure can be used to test if the filter is partially clogged. Place the NOA in
the Start or Stand-by Mode and monitor the reaction cell pressure in the
Measurement Menu or Status Menu. Note the cell pressure with the filter in-line
and then remove the filter. Normally the cell pressure will increase by ~0.1 torr
when the filter is removed. If a larger increase in cell pressure is observed,
replace the filter. These filters are disposable and are not to be cleaned.
Replacement filters are available from Sievers (HFL 01410) and from most
laboratory supply houses. The filter is Teflon to help block liquid from getting into
the restrictor and reaction cell.
Security
The security features for the NOA must be enabled by Sievers personnel during
installation. Once enabled, passwords are required to change the setup of the
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