Brooks Instrument Mfi Series - Manual (Page 49)

4-11
Brooks ® Mf Series
Section 4 Maintenance &
Troubleshooting
Installation and Operation Manual
X-TMF-Mfi-Mfx-MFC-eng
Part Number: 541B074AAG
August, 2009
10.Install the coil assembly (21) over the valve stem assembly (24) and
secure with jam nut (20). Make sure O-rings (1) are installed on
retaining plate (23) and jam nut (20).
11.Install the PC board (20) and two screws. Plug the connector from the
sensor assembly onto the PC board. The flow arrow on the connector
should be pointing toward the valve assembly. Attach PC board ground
lug to body with screw and washer (41, 42). Install the grounding spring
(43) in the flat bottom hole on the body.
12.Install the electronics housing (6) on the controller, secure with four
screws (4).
13.Connect the valve wires to terminal (TB-3). Tighten P67 fitting into
eletronics housing and tighten dome nut. Plug in signal wire terminal.
Strip connectors TB-1 and TB-2.
14.Install cover (3) and tighten four screws until cover touches electronics
housing.
15.Prior to installation, leak and pressure test to any applicable pressure
vessel codes.
C. Normally Closed Valve Adjustment
The Mf Series control valve has been factory adjusted to insure proper
operation. Readjustment is only required if any of the following parts have
been replaced: ( Refer to Figure 4-3a ).
orifice (33)
valve stem (24)
plunger (26)
lower guide springs (29)
valve seat (32)
The valve is adjusted in Brooks Mass Flow Controllers by adding spacers
(28A and 28B) to the control valve assembly to vary the air gap and initial
preload. Spacers are used to affect the proper adjustment because they
provide a reliable and repeatable means for adjustment. Screw type
adjustment mechanisms can change with pressure or vibration and
introduce an additional dynamic seal that is a potential leak site and source
for contamination. (Refer to Figure 4-3a) for spacer locations.