Brooks Instrument 5851i - Manual (Page 35)

4-7
Installation and Operation Manual
X-TMF-5851i-MFC-eng
Part Number: 541B109AAG
September, 2009
Brooks ® Model 5851 i
Section 4 Maintenance
& Troubleshooting
8. Purge the assembled controller with dry nitrogen.
9. Perform the calibration procedure in Section 3-4.
10. When the controller is re-installed in the system, the connections
should be leak-tested and the system should be purged with dry
nitrogen for 30 minutes prior to start-up to prevent the formation of
deposits.
4-3 Sensor Tube
The sensor tube is part of a calibrated flow divider that is designed to
operate within a preset gas flow range. The sensor assembly may be
removed or replaced by referring to Section 4-4, Disassembly and
Assembly. If the sensor assembly is cleaned and reinstalled, a calibration
check should be performed. Refer to Section 3-4.
4-4 Disassembly and Assembly
The Model 5851 i Mass Flow Controller may be disassembled in the field
by the user for cleaning, reranging or servicing. Disassemble and
assemble the controller as follows:
NOTE: The 5851 i Mass Flow Controller should be disassembled and
assembled in a clean environment to prevent particulate contamination.
A. Disassembly
The numbers in parentheses refer to the spare parts exploded view in
Figure 5-1.
1. Remove the jam nut (1) on top of the valve assembly.
2. Unplug the valve connector from the electronics cover and remove the
coil assembly (2).
3. Remove the hex socket screws (3) securing the valve retaining plate
(4) attaching the valve stem assembly (6).
4. Carefully remove the valve stem assembly (6).
5. Remove the plunger assembly (7, 8, 9 and 11).