DH Instruments PPCH-G, Руководство по эксплуатации и обслуживанию

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PPCH-G™ OPERATION AND MAINTENANCE MANUAL
© 2007 DH Instruments, a Fluke Company Page 50
The effect of the thermal pressure control unit (TPCU) used in standard dynamic control
mode makes it difficult to run a reliable leak test when the PPCH-G is in dynamic control mode.
Before leak testing, change the control mode to a mode other than standard dynamic and wait at
least 5 minutes for the TPCU to cool down and stabilize (see Section 3.4.6.2).
To access the LEAK CHECK function, press
[LEAK CHECK]
from the MAIN RUN screen.
Select
<1run>
to run a leak test. The display is:
1. Edit field for the time over which the leak check pressure
change will be measured, in seconds.
Set leak check time:
15 s
Edit the leak check time if desired (minimum 1, maximum 999) and press
[ENT]
.
Press
[ENT]
again when ready to start the leak test. The leak test display is:
1. Standard MAIN RUN screen first line showing measured
pressure.
2. Active RPT position indicator
3. Indication that leak test is running and countdown of time
remaining.
70.089 MPa a HI
Leak testing 13 s
[ESC]
can be used to abort the running leak test.
[ENT]
while the leak test is running
restarts the leak check timer. When the leak check timer countdown has completed PPCH-G
beeps three times and the leak check results screen is displayed:
1. Total pressure change from start to finish of leak check time.
2. Indicator of RPT used to run leak check.
3. Average rate of change of pressure over the leak check
time period.
∆ P 0.61 MPa HI
Rate 0.04 MPa/sec
From the leak check results screen, press
[ENT]
to repeat the leak test.
Press
[ESC]
to return to leak check main menu and exit to the MAIN RUN screen.
As a general rule, the maximum acceptable leak rate for optimal PPCH-G automated
pressure control operation and to assure in tolerance measurements with default pressure control
parameters is 0.002 % of reading/second. In dynamic control mode, to handle higher test system leak
rates, increase the hold limit using [SPECIAL], <6control>, <1limits> (see Section 3.4.6.1) or try using
hi volume dynamic control (see Section 3.4.6.2).
To view the results of the most recently completed leak check, press
<2view>
.
Press
[ENTER]
or
[ESC]
to return to the MAIN RUN screen. If NO leak check data is stored
(i.e., if the PPCH-G has never run a leak test or a reset has cleared previous leak test results),
the results screen displays
<Data NOT available>
briefly and returns to MAIN RUN screen.