Brooks, Mf series – Brooks Instrument Mfi Series User Manual

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4-5

Brooks

Mf Series

Section 4 Maintenance &

Troubleshooting

Installation and Operation Manual
X-TMF-Mfi-Mfx-MFC-eng
Part Number: 541B074AAG
August, 2009

2. Connect the instrument to a source of gas on which it was originally

calibrated. Adjust the setpoint for 100% flow. Adjust flow to 100%
indication (5.00 V) and adjust the inlet and outlet pressures to the
calibration conditions. Verify that the output signal reaches and
stabilizes at 5.00 Volts or 20 mA. Vary the setpoint/flow rate over the 2-
to-100% range and verify that the output signal follows the setpoint/flow
rate. For controller apply the correct voltage to the valve override input
(TB-2, Terminal 5) and verify that the output exceeds 100%. Connect
the valve override pin to power supply common and verify that the
output signal falls below 2%. If possible, connect a flow measurement
device in series with the mass flow instrument to observe actual flow
behavior and verify accuracy of the mass flow instrument. If the mass
flow instrument functions as described above, it is functioning properly
and the problem may lie elsewhere.

Tables 4-1 and 4-2 list possible malfunctions which may be
encountered during bench troubleshooting.

C. Sensor Troubleshooting

If it is believed the sensor coils are either open or shorted, troubleshoot
using Table 4-2. If any of the steps do not produce the expected results,
the sensor assembly is defective and must be replaced. Refer to Section
4-4 for the disassembly and assembly procedures to use when replacing
the sensor.

Note: Do not attempt to disassemble the sensor.

D. Cleaning

No routine external cleaning is required for Brooks thermal mass flow
controllers/meters. Should the Mf Series mass flow controller/meter require
cleaning due to deposition, use the following procedures:

1. Remove the unit from the system.
2. Refer to Section 4-4 to disassemble the controller.

Figure 4-1 Torque Sequence for the Valve Retainer Plate (Controller)

Note: Not all components shown for clarity.

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