Servomex DF-310E, Руководство оператора

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34 DF-310E Sample Gas Preparation and Delivery
components. Depending upon the continuous acid gas level and the oxygen
level to be measured, a dilution ratio must be selected such that the resulting
O
2
level is accurately measurable and at least one order of magnitude above
the O
2
level in the N
2
dilution gas. Contact the local Servomex Business
Center for specific recommendations.
Another approach when acid gas levels are continuously above the STAB-EL
limits is to enhance the inherent capabilities of the sensor by using a scrubber
system. The scrubber will remove the bulk of the acid gases, allowing the
Analyzer to provide continuous stable measurements. If a breakthrough
occurs, the sensor's ability to tolerate high levels of acid gas for limited
periods of time will avoid catastrophic loss of performance.
Servomex offers a broad range of scrubbers for applications in severe
environments. Standard scrubber columns are available in various sizes, and
in single or dual bed configurations. The columns are fabricated from clear
PVC and are designed to accept a variety of different acid gas absorbent
media which have a color-change indication to facilitate convenient change-
out. For more information, contact the local Servomex Business Center.
6.2 Sample Gas Scale Factor
The optional GSF (Gas Scale Factor) is used to correct for changes in the rate
of oxygen diffusion when background gases other than nitrogen are present in
the process or sample gas.
In many applications, the sample GSF does not need to be altered from the
default value of 1.00. However, if the sample gas has a significantly different
diffusivity compared with nitrogen (such as helium or hydrogen), the GSF
should be applied. To use the GSF feature, the volumetric percentages of the
sample gas are entered as described on page 79 and the total GSF is
automatically calculated by the analyzer. Alternately, the GSF factor can be
entered manually.
The software in the analyzer supports gases as shown in Table 3.
Contact the local Servomex Business Center for assistance with gases not
listed.
For additional information see the section on Gas Scale Factor in the User
Interface chapter on page 79.