3. GENERAL OPERATION
Page 59
© 1998-2008 DH Instruments, a Fluke Company
Table 18
.
Valve Settings for Operating in Differential Mode
VALVE
VALVE SETTING
Control Selection
To adjust pressure under PG7000 piston: PG
To adjust static pressure: STATIC P
PG Shutoff
Piston is floating or near floating: OPEN
Any other time: CLOSED
Test Bypass
To make differential pressure measurements: CLOSED
To set or check DUT zero: OPEN
Static P Selection
OFF
If static pressure is atmospheric pressure: VENT or OFF
For the highest quality differential mode measurements, use consistent
conditions for static pressure and PG7000 vacuum reference pressure at each point.
Set the PG7000 Differential Mode Interconnections Kit CONTROL valve to STATIC P
to readjust the static pressure to the same value at each point if necessary. This
value should be the same as the value at which the RPM offset was determined.
Typical Differential Mode Operational Sequence
See Figure 9 for a schematic of the Differential Mode Controller and its valves.
Set RPM offset at desired static pressure (see Section 3.9.4.1, Selecting
Differential Mode, Setting Static Pressure, Finding RPM Offset (
<1run>
)).
Select
pressure to mass
or
mass to pressure
mode (see Section 3.9.12).
Put the Differential Mode Controller PG SHUTOFF valve in CLOSED position.
If desired, read DUT output at zero differential pressure with
TEST BYPASS valve open. Put TEST BYPASS valve in CLOSED position. If
desired, put CONTROL valve in STATIC P position and use system control
component to adjust static pressure to starting value.
Press
[ENTER]
and enter a pressure or mass value. Load mass as instructed
on PG7000.
Install bell jar on PG7000, shut the PG7000 vacuum vent valve, open vacuum
reference shutoff valve. Wait for vacuum under bell jar to reach
Ready
condition. If using AMH-38 automated mass handler and mass loading
resolution of 0.1kg, mass can be changed without breaking vacuum.
Put CONTROL valve in PG position and use system control component to float
PG7000 piston. Slowly put PG SHUTOFF valve into OPEN position. Readjust
pressure to float the PG7000 piston if necessary.
If desired, put CONTROL valve in STATIC P position and use system control
component to adjust static pressure to starting value.
When PG7000 indicates
Ready
on all
Ready/Not Ready
indicators, take DUT
reading at differential pressure indicated on the top line of the PG7000 display.
Slowly put PG SHUTOFF valve in CLOSED position.
Shut vacuum reference shutoff valve, open vacuum vent valve. Wait for
pressure under bell jar to return to ambient. Remove bell jar. This step is not
necessary is using AMH-38 automated mass handler and mass loading
resolution of 0.1 kg.