DH Instruments PPCH, Руководство по эксплуатации и обслуживанию

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PPCH™ OPERATION AND MAINTENANCE MANUAL
© 2009 DH Instruments, a Fluke Company Page 40
Pressing [+/-] from the MAIN RUN screen provides a shortcut to a momentary view of the
range identification screen for the active range.
PPCH saved AutoRange ranges that use Q-RPTs in external RPM4s are available for
selection from the [RANGE] key. AutoRange ranges saved locally on the RPM4, are not available
on the PPCH [RANGE] key.
Many PPCH settings and functions are range specific. See Table 7 for identification of
range specific settings.
To protect against overpressure situations and for maximum measurement performance,
the active range can only be changed when the system is vented. If [ENT] is pressed while in the
RANGE function when PPCH is NOT vented, the display indicates <Vent system fully to change
range>. Pressing the [VENT] key causes PPCH to vent and complete the range change.
Before operating PPCH with external Q-RPTs, check carefully that the external Q-RPT
TEST(+) port is connected to the PPCH TEST port. If the external Q-RPT is NOT connected to the
PPCH TEST port, it will not measure the pressure generated by PPCH and PPCH 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. When using
external Q-RPTs in RPM4s as reference pressure measurement devices with a PPCH, 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 is protected automatically.
3.3.2 [UNIT]
 PURPOSE
To select the unit of pressure in which PPCH displays pressure values.
For information on selecting the measurement mode (absolute, gauge), see Section 3.3.3.
 PRINCIPLE
PPCH allows the unit of measure in which pressure values are displayed to be changed.
PPCH supports 15 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 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).