Brooks Instrument QMBM - Manual (Page 42)

Section 4 Maintenance
4-2
Installation and Operation Manual
X-CM-QmB-eng
Part Number: 541B029AAG
June, 2011
QmB Series IP40, IP66, IP66XP
4-2 Troubleshooting
System Checks
Internal seals and component alignments are extremely critical
within this device. Improper servicing of your Quantim can cause
malfunction of the device and/or personal injury. This device
be serviced by factory personnel only. There are no customer
serviceable components within the device. Disassembly of this
device voids all warranties, explicit or implied.
must
WARNING !
Quantim Flow Meters and Controllers are typically used as a critical
component in fluid systems. These systems can be complex in nature and
therefore isolating a malfunction has to be done with a system perspective.
An incorrectly diagnosed malfunction can cause many hours of
unnecessary downtime. If possible, perform the following system checks
before removing a suspect Mass Flow Meter or Controller for bench
troubleshooting or return to the factory
(especially if the system is new):
1. Identify a low resistance common connection and make sure that the
correct power supply voltage and signals are present at the connector
of the Quantim device.
2. Verify that the process fluid connections have been made correctly,
and that they have been tested for leaks.
3. If the Mass Flow Controller appears to be functioning but cannot
achieve setpoint, verify that there is sufficient inlet pressure and
pressure drop at the controller to provide the required flow.
4. Flow control instability can be a result of using Quantim in a system
that includes other active control elements such as pressure regulators.
Depending on the tuning constants used in the Quantim and the control
dynamics of the other active elements, these devices can interfere with
each other and cause flow instabilities. It is very important to take a
complete system perspective when applying Quantim to flow control
applications.