Brooks Instrument Mfi Series - Manual (Page 41)

4-3
Brooks ® Mf Series
Section 4 Maintenance &
Troubleshooting
Installation and Operation Manual
X-TMF-Mfi-Mfx-MFC-eng
Part Number: 541B074AAG
August, 2009
Table 4-1 Bench Troubleshooting
Trouble Possible Cause Check/Corrective Action
Actual flow overshoots controller setpoint Anticipate potentiometer out of Adjust anticipate potentiometer. Refer to Section 3-5.
by more than 5% full scale.* adjustment
Output stays at zero and there is flow Clogged sensor. Clean sensor.Refer to cleaning, Section 4-2d.
through instrument
Output stays at zero regardless of setpoint/ Clogged control valve.* Check TP3 with the setpoint at 100%. If the voltage is greater
flow and there is no flow through the than 11V, disassemble and repair the control valve. Refer to
controller. Section 4-4c.
Valve override input is grounded.* Check valve override input (TB-2, Terminal 5).
Defective PC board. Replace PC board. Refer to Section 4-4.
Output signal stays at +6.8 V or 26 mA Valve stuck open or leaky.* Clean and/or adjust control valve. Refer to cleaning procedure
regardless of setpoint and there is flow and/or Section 4-4c.
through the instrument.
+15 V -28 Vdc applied to the valve Check the valve override terminal (TB-2, Terminal 5).
override input.*
Defective PC board. Replace PC board. Refer to Section 4-4.
Controller output signal follows setpoint at Leaky control valve. Disassemble and repair valve. Refer to Section 4-4c.
higher setpoints but will not go below 2% .*
Controller output signal follows setpoint at Insufficient inlet pressure or pressure drop. Adjust pressures, inspect in-line filters and clean/replace as
lower setpoints but does not reach necessary.
full scale.*
Partially clogged sensor. Check calibration. Refer to Section 3-4.
Partially clogged valve. Disassemble and repair control valve. Refer to Section 4-4.
Valve out of adjustment. Adjust valve. Refer to Section 4-4.
Valve guide spring failure. Controller oscillates (see below).
Instrument grossly out of calibration. Flow is Partially clogged sensor. Clean sensor, refer to the cleaning procedure, Section 4-2d.
higher than desired.
Instrument grossly out of calibration. Flow is Partially clogged restrictor. Replace restrictor. Refer to Section 4-4.
lower than desired.
Instrument oscillates. Pressure drop or inlet pressure excessive.* Adjust pressures.
Oversized orifice.* Check orifice size. Refer to Section 4-5.
Valve out of adjustment.* Adjust valve. Refer to Section 4-4c.
Anticipate potentiometer out of adjustment. Adjust anticipate potentiometer. Refer to Section 3-4.
Faulty pressure regulator. Check regular capacity.
Defective PC board. Replace PC board. Refer to Section 4-4.
*For controller only (Models Mf50/51/53).