3. OPERATION
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© 2007 DH Instruments, a Fluke Company
Before operating PPCH-G with external Q-RPTs, check carefully that the external Q-RPT
TEST(+) port is connected to the PPCH-G TEST port. If the external Q-RPT is NOT connected to
the PPCH-G TEST port, it will not measure the pressure generated by PPCH-G and PPCH-G may
reach a pressure higher than the target pressure before its watchdog function recognizes that
the external Q-RPT is not connected.
Take care not to overpressure external Q-RPTs when using them with a PPCH-G. When using
external Q-RPTs in RPM4s as reference pressure measurement devices with a PPCH-G, the user is
responsible to setting up hardware and following procedures to protect lower range Q-RPTs from
overpressure. Only the Lo Q-RPT (IL) built-into the PPCH-G is protected automatically.
3.3.2
[UNIT]
PURPOSE
To select the unit of pressure in which PPCH-G displays pressure values.
For information on selecting the measurement mode (absolute, gauge), see Section 3.3.3.
PRINCIPLE
PPCH-G allows the unit of measure in which pressure values are displayed to be changed.
PPCH-G supports 17 different pressure units of measure as well as user defined units.
To simplify operation, quick access to six unit choices is made available under the
[UNIT]
key.
The default units available depend on whether the PPCH-G was originally configured as an
SI or US version. The
[UNIT]
key contents can be customized by the user to any
configuration of six units (see Section 3.5.6).
Internally, PPCH-G always operates in Pascal (Pa), the SI unit of pressure. Values of
pressure are represented in other units by the application of conversion factors to convert from
Pa (see Section 7.2.1).
OPERATION
To change the pressure unit of measure for the active
range, press
[UNIT]
from the MAIN RUN screen while
the range is active. The display is:
1MPa 2kPa 3hPa
4bar 5mbar 6psi
The cursor is on the number corresponding to the pressure unit of measure active for the current range.
To change the pressure unit of measure, select the desired unit. Making the selection
returns to the MAIN RUN screen with the selected unit active.
The pressure measurement unit selected is range specific. When in a given range, all
functions and settings are represented in the current measurement unit for that range. However,
certain internal and/or metrological functions (e.g., Q-RPT calibration coefficients) are always
represented in Pa regardless of the active range unit of measure.
