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RPM4™ OPERATION AND MAINTENANCE MANUAL
© 2004-2007 DH Instruments, a Fluke Company Page 76
Operation returns to normal when the disagreement between the two Q-RPTs
returns to normal.
When using parallel measurement mode, the Hi and Lo Q-RPTs should be
connected IN PARALLEL to the pressure to be measured (both Q-RPTs
connected to the same pressure). The measured pressure indicated in
parallel measurement mode is the average of the Hi and Lo Q-RPTs.
3.5.7.4 <4LO VNT>
PURPOSE
To cause an RPM4’s Gxxx or BGxxx Q-RPT TEST(-) vent valve to stay open or
closed rather than open and close automatically.
This feature is active only when the active Q-RPT is a Gxxx (gauge) or
BGxxx (bi-directional gauge) Q-RPT.
PRINCIPLE
An RPM4 equipped with a Gxxx (gauge) or BGxxx (bi-directional gauge) Q-RPT has
a TEST(-) vent valve in its Q-RPT module (see Figure 8, Gxxx, BGxxx, Valve C).
The TEST(-) vent valve is used to open the TEST(-) port to atmosphere which
also connects the Q-RPT and the device or system under test low side to atmosphere.
In normal RPM4 operation, the TEST(-) valve is closed to isolate the low pressure
circuit from fluctuations in ambient pressure when the Q-RPT is being used to
measure pressure. It is open only when SDS is closed (see Section 3.2.7).
However, it may be desirable to open the TEST(-) port to atmosphere while
measuring pressure and/or without closing SDS. For example, this may be
necessary to assure that the pressure on the low side of the Q-RPT and the
system under test does not move too far away from atmosphere. [SPECIAL],
<7internal>, <4lo vnt> allows the TEST(-) vent valve to be set to be
permanently open, permanently closed or to operate in its default, automated
condition. It also allows the current status of the valve to be viewed.
OPERATION
The normal, default setting for the TEST(-) vent valve is <1auto> in which RPM4
automatically controls the valve based on current Q-RPT module operation.
Setting other than <1auto> should only be selected by advanced users.
To access the LO VNT function press [SPECIAL], <7internal>, <4lo vent>. If the
RPM4 does not have a Gxxx (gauge) or BGxxx (bi-directional gauge) Q-RPT, the
display is: <Available with Gxxx or BGxxx Q-RPT only>. If the RPM4 has
more than one Gxxx or BGxxx Q-RPTs, the Hi or Lo Q-RPT must be selected.
The next display is:
Test(-) vent:1auto
2open 3close 4view
Select <1auto> for the TEST(-) vent valve operation to be controlled automatically
by RPM4 based on current operation. This is the default and recommended setting.
Select <2open> to cause the TEST(-) valve to open and remain open regardless
of RPM4 operation until the setting is changed. If RPM4 detects a condition