Brooks Instrument 5851i - Manual (Page 49)

4-21
Installation and Operation Manual
X-TMF-5851i-MFC-eng
Part Number: 541B109AAG
September, 2009
Brooks ® Model 5851 i
Section 4 Maintenance
& Troubleshooting
Assembly Procedures
1. Select the proper restrictor element combination.
2. When handling restrictor elements, use care to insure that they are not
contaminated with dirt, grease, oil, etc. The use of rubber gloves is
recommended.
3. Put a lightly lubricated O-ring onto the header plate. The restrictor
assembly can then be installed in the mass flow controller body
(restrictor element(s) go in first). It is important that the restrictor
assembly is put into the body in the correct orientation (Refer to Figure
4-7). Push this assembly in with your fingers. Do not use an arbor press
or hammer to install the restrictor assembly. The restrictor assembly
should be pushed in until it bottoms out. Do not force it beyond this point.
4. Place the end block O-ring in position and install the end block with the
four hex socket screws. Tighten these screws to 49 in./lbs. Do not over-
tighten.
5. Install the inlet adaptor fitting and O-ring.
6. Calibrate the mass flow controller (Refer to Section 3-4). If the TP2
voltage as calculated in the calibration procedure, Section 3-4, step f, is
below 1.2 volts, the flow rate will be greater than desired. If this occurs,
the restrictor assembly should be replaced with the next lower flow rate
assembly. If the TP1 procedure, Section 3-4 step f is greater than 4.5
volts, the flow through the controller will be less than desired. If this
occurs, the restrictor assembly should be replaced with the next higher
flow rate assembly.