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GA0383P02 Rev. C
Sampling System Components
As noted, the GCM-A’s sampling system is composed of a pipe network that delivers an air
sample to the GCM-A. The individual components of a GCM-A sampling system may differ
from installation to installation (see isometric views Figures 5 though 8 of an open and
closed circuit application). In most instances, the following components are used (see
Figures 9 through 14 for component details):
• Zone Manifold – Two Zone Manifolds are used in the GCM-A system; one for the
Ambient signal, the other for the Generator signal. These components are typically
installed close to the GCM-A and are used to adjust airflow from each segment of the
sampling system network. Each Zone Manifold will be supplied with pipe unions to ease
removal of these components from the sampling system should the need arise.
Communication between Environment One and the power plant customer will confirm
the particular configuration of the pipe unions. A Zone Manifold also contains a
replaceable filter that helps guard against dirt and insects from entering the inlet manifold
of the GCM-A system (possibly obstructing flow).
• Sampling pipe — This material is supplied by the site. Communication between
Environment One and the power plant customer will determine necessary lengths. It is
the responsibility of site management to assure that sampling system piping is installed
in accordance with sampling system design parameters, local codes and professional
practice.
• Sample Heads — Sample Heads may be used as part of the sampling system, and
particularly for the Ambient signal. Sample Heads have a fixed orifice and contain a
replaceable filter that helps guard against dirt and insects from entering the sampling
system (possibly obstructing flow); see Figure 13.
• Sample Probes — Sample Probes are sections of sampling system pipe that have
holes drilled in them at particular spacing and with particular diameters. They are used as
an alternative to Sample Heads and are often preferred for the Generator signal portion of
the sampling system because of their inherent flexibility. Communication between
Environment One and the power plant customer will determine whether Sample Probes
will be used in a GCM-A sampling system; see Figure 14.
• DP Gage — The DP Gage is an external metering component used to confirm the air
flow across a Zone Manifold. The default GCM-A system design parameter for air flow is
14 LPM for each sample line. The DP Gage will be utilized during system commissioning
and at maintenance intervals to validate sampling system operation; see Figure 18.
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