Brooks Instrument 5851E - Manual (Page 51)

Brooks ® Model 5851E
4-19
Section 4 Maintenance
Installation and Operation Manual
X-TMF-5851E-MFC-eng
Part Number: 541B104AAG
November, 2008
Table 4-5 Restrictor Selection Guide
Example:
The desired gas is Silane (SiH4)
The desired full scale flow rate is 200 sccm.
Sensor conversion factor is 0.625 from Table 4-3.
Nitrogen equivalent flow = 200/0.625 = 320 sccm Nitrogen
In the example above, the restrictor should be sized for a 320 sccm flow
rate.
If a restrictor assembly is being replaced because the original has become
contaminated, the original may be used as a guide to select the
replacement assembly. The porosity of the original element or elements is
marked on the calibration sheet which was shipped with the flow controller.
The replacement assembly should be replaced in the same orientation as
the original restrictor.
Assembly Procedure
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 O-ring onto the header plate. The restrictor assembly can
then be installed in the MFC 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 4-6). 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
4 hex socket screws. Tighten these screws to 49 inch-lbs. Do not over
tighten.
The end block screws (31) and the valve screws (3) are not
interchangeable. The end block screws are stronger and are needed
to achieve the pressure rating. The end block screws are darker in
color and can be attracted by a magnet.
CAUTION
5. Install the inlet adaptor fitting.
Range slpm Restrictor Element Part Number
Nitrogen Equivalent Flow* Combination
4.6 to 15 1-40 micron (1 inch) S613E604BMT
15 to 26 1-40 micron S613E636BMT
26 to 42 2-40 micron S613E523BMT
42 to 60 3-40 micron S613E526BMT
60 to 79 2-40 micron/1-60 micron S613E528BMT
79 to 93 1-40 micron/2-60 micron S613E529BMT
93 to 130** 3-60 micron S613E527BMT
*Based on 0°C Standard Reference Temperature
**For Hydrogen from 130 slpm to 200 slpm use 3-60 micron restrictor elements.
Note: If the air equivalent flow is between two sizes, choose the larger size.