DH Instruments PPC2+, Manual

Page: 48 / 166

PPC2+™ Operation and Maintenance Manual
©2001 DH Instruments, Inc.
Page 40
3.2.6.1 TURNING-OFF CUSTOM CONTROL PARAMETERS
To return to default pressure control parameters for the active range and control
mode, select the control mode using the CONTROL function (see Section 3.2.3).
3.2.7 HEAD
m
PURPOSE
To cause a pressure value representing a difference in height to be added to the pressure
measured by the PPC2+ reference pressure transducer.
m
PRINCIPLE
PPC2+’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 PPC2+’s TEST port.
This difference in height, frequently called head, can cause a significant difference
between the pressure measured by the PPC2+ 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 PPC2+ RPT at its test
port in order to accurately predict the pressure actually applied at a different height.
PPC2+ 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 PPC2+ TEST port and another height.
The height units and the test gas are specified under by pressing [SPECIAL] and
selecting <2Head> (see Section 3.2.7).
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