Brooks Instrument 4800 Series - Manual (Page 26)

4-4
Brooks ® 4800 Series
Section 4 Maintenance and Troubleshooting Installation and Operation Manual
X-TMF-4800-MFC-eng
Part Number: 541B072AAG
September, 2013
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.
Bench Troubleshooting
1. Establish a proper connection between the Brooks 4800 Series Mass
Flow Meter or Controller (using Figure 4-1 as a reference). Switch on
the power and allow the instrument to warm-up for 15 minutes. In case
of a Controller model, adjust the Setpoint to zero. Do not connect the
device to a gas source yet. Observe the output signal and, if necessary,
perform the zero adjustment procedure (see Section 3 for information
about the zeroing function). If the output signal does not zero properly,
please contact Brooks Instrument.
2. Connect the instrument to a source of the same gas used for it's
original calibration. Regulate the Setpoint to 100% flow and adjust the
inlet and outlet pressures to calibration conditions. Verify that the output
signal reaches its full scale value and stabilizes at that value. Vary the
command voltage over the 1 to 100% range and verify that the output
signal follows the Setpoint If possible, connect a flow measurement
device to monitor the actual flow behavior and verify the accuracy of the
mass flow instrument. If the mass instrument performs as described
above, then it is functioning correctly and the problem may lie else-
where.
Table 4-1 lists possible malfunctions which may be encountered during
bench troubleshooting.
For Controller Models Only: Apply +5 Vdc to the +15 Vdc valve override pin
(pin 12) and verify that the output exceeds 100%. Connect the valve
override pin to earth and verify that the output signal falls below 2%.