PRESSURE DETECTOR FUNCTIONAL USES
Pressure Detectors
PRESSURE DETECTOR FUNCTIONAL USES
Pressure measurement is a necessary function in the safe and efficient operation
of DOE nuclear facilities.
EO 1.3
STATE the three functions of pressure measuring
instrumentation.
EO 1.4
DESCRIBE the three alternate methods of determining
pressure when the normal pressure sensing devices are
inoperable.
EO 1.5
STATE the three environmental concerns which can
affect the accuracy and reliability of pressure detection
instrumentation.
Pressure Detector Functions
Although the pressures that are monitored vary slightly depending on the details of facility
design, all pressure detectors are used to provide up to three basic functions: indication, alarm,
and control. Since the fluid system may operate at both saturation and subcooled conditions,
accurate pressure indication must be available to maintain proper cooling. Some pressure
detectors have audible and visual alarms associated with them when specified preset limits are
exceeded. Some pressure detector applications are used as inputs to protective features and
control functions.
Detector Failure
If a pressure instrument fails, spare detector elements may be utilized if installed. If spare
detectors are not installed, the pressure may be read at an independent local mechanical gauge,
if available, or a precision pressure gauge may be installed in the system at a convenient point.
If the detector is functional, it may be possible to obtain pressure readings by measuring voltage
or current values across the detector leads and comparing this reading with calibration curves.
Environmental Concerns
Pressure instruments are sensitive to variations in the atmospheric pressure surrounding the
detector. This is especially apparent when the detector is located within an enclosed space.
Variations in the pressure surrounding the detector will cause the indicated pressure from the
detector to change. This will greatly reduce the accuracy of the pressure instrument and should
be considered when installing and maintaining these instruments.
IC-02
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