DH Instruments FPG8601, Руководство по эксплуатации и обслуживанию

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6. FPG TOOLS
Page 103 © 2007 DH Instruments, a Fluke Company
6.9.2 [ABSOLUTE MODE], [GAUGE MODE]
The
[Units]
menu contains selections for measurement mode changes:
[Gauge Mode]
and
[Absolute Mode]
. Prior to selecting either of these modes, make sure all the necessary
pneumatic connections are complete. Refer to Section 4.6 for the hardware requirements of
changing measurement mode. If the system is properly connected, changing measurement
modes simply requires the selection of the
[Gauge Mode]
or
[Absolute Mode]
menu
options. There is typically a minimum 30 minute warm up time required to allow total
equilibrium of conditions around the load cell when measurement modes are changed.
Prior to changing the current FPG measurement mode, make sure that the FPG, VLPC and
the DUT (if connected) are properly connected with all of the necessary plumbing. Refer
to Sections 4.6 and 4.10 for information on how to set up the FPG for a specific
measurement mode.
If the
<Operation Abort>
option is used during measurement mode changes, it is up to the
user to automatically make the necessary valve adjustments to complete the process.
FPG Tools
does not determine the measurement mode based on the current valve state.
The last attempted measurement mode is always used regardless of the valve state.
6.9.2.1 [GAUGE MODE]
Gauge mode operation requires a lubrication pressure of roughly 135 kPa and a
reference port pressure equivalent to ATM. FPG Tools automatically adjusts the
necessary internal valves to obtain this condition. The specific sequence
involved when changing to gauge mode is detailed below.
When changing from absolute to gauge mode, never expose the reference
chamber of the FPG to ATM until the lubrication pressure exceeds ATM.
Failure to follow this step will reverse the pressure direction of the
lubrication gas possibly contaminating the flow pass between the piston and
cylinder.
Vent all system pressure through the VLPC (if active) and open the system
bypass valve.
The internal gauge mode valves are adjusted to set the pressure in the
lubricating volume.
Allow the lubrication pressure to increase to roughly 140 kPa.
FPG Tools does not look for any level of system stability when changing
measurement modes. The system is now in gauge mode with the system
bypass valve open and the VLPC is set to the lowest available gauge
pressure range.
If the FPG was changed from absolute mode, purge the lubrication volume
using the [Purge] toolbar function. This step can be included in the
automated range change sequence (see Section 6.6.2.1). Allow at least 30
minutes before continuing to the next step.
Zero the FPG, then run an internal calibration.