DH Instruments PPCK PLUS, Руководство по эксплуатации и обслуживанию

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PPCK+™ Operation and Maintenance Manual
©2001 DH Instruments, Inc .
Page 38
3.2.7 [HEAD]
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PURPOSE
To cause a pressure value representing a difference in height to be added to the
pressure measured by the PPCK+ reference pressure transducer.
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PRINCIPLE
PPCK+'s reference pressure transducers measure gauge or absolute pressure at the
height of the rear panel TEST port. Frequently, when performing a calibration or test,
the device or system under test is at a different height than the PPCK+’s TEST port.
This difference in height, frequently called
head , can cause a significant difference
between the pressure measured by the PPCK+ at its TEST port height and the pressure
actually applied to the device under test which is at a different height. In this case, it is
useful to make a head correction to the pressure measured by the PPCK+ RPT at its test
port in order to accurately predict the pressure actually applied at a different height.
PPCK+ can accurately calculate head pressures for nitrogen, helium and air as the test
gas over its working pressure range. The HEAD function allows the height difference to
be specified and causes the resulting head pressure to be added to the pressure
measured at the TEST port.
The [HEAD] function key is used to turn the head correction function ON and OFF and to
specify the height difference between the PPCK+ TEST port and another height.
The height unit of measure and the test gas are specified by pressing
[SPECIAL] and
selecting <2Head> (see Section 3.4.2).
In PPCK+’s measurement ranges with gas as the test medium, specifying the head height
within
±
30 cm (12 in.) is adequate to assure that, even in the worst case, the
uncertainty on the head correction will be insignificant relative to the tolerance on the
measurement.
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OPERATION
To access the HEAD function, press the [HEAD] function key. The display is:
1. Test gas currently specified for the head correction.
2. Entry field for head height.
2
Edit head height:
95 cm N2