Specifications

3. OPERATION
Page 51 © 1998-2007 DH Instruments, a Fluke Company
After 30 seconds, if the stability check is not passed, molbox RFM displays:
• If the pressure was not stable:
Leak is too large to
continue
• If the molbloc temperature change
was too great:
Temp change was too
great to find leaks
• If the offset between the RPTs was
too great:
Offset excessive
check tare
If any of the above three prompts occurs, check the external system for leaks
and/or run the molbox RFM leak check before proceeding. If the tare was
excessive, tare the molbox RPTs before running the leak check again (see Section
3.4.4.1).
Once the 30 second pressure stability/offset
check has been successfully completed,
molbox RFM displays:
347.592 kPaa 347.583
0.101 sccm [ENT]
When [ENTER] is pressed, molbox RFM’s valves actuate to set up the system
leak check configuration which is identical to the normal operating configuration
(see Figure 3). The display becomes:
1. Pressure read by the upstream RPT (left), the
downstream RPT (right) and the pressure unit
of measure (middle).
2. Current measured flow.
3. Time remaining in the leak check in seconds.
347.592 kPaa 347.583
0.101 sccm 30
molbox RFM measures pressure and flow for a 40 second countdown. After the
countdown has elapsed, molbox RFM displays its conclusion from the
measurements. The display will be either:
possible system
upstream leak
or
possible system
downstream leak
or
System passed system
leak check
Upstream and downstream refer to the possible location of the leak relative to
the position of the molbloc and the normal flow direction in the system. If you are
unable to locate a leak in the flow path components, check or replace the
upstream and downstream molbloc to molbox pressure tubes and their connectors
and retry the test. They are a critical part of the pneumatic system and if a
significant leak is present in these tubes, it will cause an error in flow
measurement.
 OPERATION – molbloc-S Operation
In molbloc-S operation, SYSTEM LEAK CHECK is a one-part test which tests for
pressure decay in the closed system.
To access the system leak check press [TARE] and select <3leak check>,
<2system>.
The display is:
Leak check:
1run 2view
If <2view> is selected the test results screen (see below) is displayed with the
results from the most recent leak test.