MKS Baratron 223B, Инструкция по эксплуатации, Страница: 21 / 31

Chapter Four: Operation How To Adjust the Zero Pot
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Chapter Four: Operation
How To Adjust the Zero Pot
For correct operation, the only adjustment necessary will be trimming of the zero pot, whose
location is clearly marked on the transducer cover. Zeroing must be done only when one is
assured of zero differential pressure across the sensor. This may be accomplished most reliably
by installing the transducer in its system using a pair of isolation valves, one in either pressure
line, and a cross-porting valve connecting the two sensor ports. A zero differential pressure is
assured when both isolation valves are closed and the cross-porting valve is open. Normal
operation is returned by closing the cross-port valve and opening the isolating valves. Use of
these valves makes it possible to remove the sensor from the system, while maintaining system
pressure integrity.
Other than zero adjustment, recalibration of the instrument should not be undertaken as the span
and linearity pots interact. Consult the factory if the calibration is out of specification.
Contamination (moisture and dirt) may affect the stability and sensitivity of the sensor,
particularly in the P
R
side as this side contains the sensing electrode. If contamination (particles)
is expected, suitable traps or filters should be used; if vapor condensation is encountered,
warming the sensor (no higher than 60° C may help. To remove condensate, evacuate both P
X
and P
R
cavities with a mechanical vacuum pump. Once a sensor is contaminated with dirt
(particles), factory cleaning or sensor replacement will be necessary.