Brooks Instrument 5866M - Manual (Page 28)

5-5
Troubleshooting
1. Remove the unit from the system.
2. Refer to Section 5-3 to disassemble the controller.
Do not soak the pressure transducer assembly in a cleaning
solution. If solvent seeps into the transducer assembly, it may
damage the transducer or, at least, significantly alter its operating
characteristics.
CAUTION
3. Inspect the orifice for clogging by holding it in front of a light source and
looking for light through the bore. Clean by soaking in a suitable non-
residuous solvent and directing a stream of compressed dry nitrogen
through the bore.
4. Deposits of silicon dioxide may be removed by soaking the internal
parts in a solution of 5% hydrofluoric acid (5 parts hydrofluoric (HF), 95
parts water (H
2
O) followed by Freon TF TM .
5. Blow all parts dry with dry nitrogen and reassemble. Refer to Section 5-4
Assembly Procedure.
6. Purge the assembled controller with dry nitrogen.
7. Perform calibration procedure in Section 6 if needed.
8. When the controller is reinstalled in the system, the connections should
be leak-tested and the system should be purged with dry nitrogen or
argon for thirty minutes prior to start-up to prevent the formation of
deposits.
5-4 Assembly
The assembly procedures below detail the downstream control version of
the Model 5866 with a Normally Closed control valve. The procedures for
the upstream control version and the Normally Open control valve are
substantially the same.
Do not get halocarbon grease on the hands. This is a special inert
lubricant which is not easily removed.
CAUTION
Note: It is recommended that all O-rings be replaced during assembly. All
O-rings should be lightly lubricated with halocarbon lubricant prior to their
installation.
Note: Gloves should be worn to reduce the possibility of contaminating the
Model 5866 or process.
A. Assembly Procedure [numbers in ( ) refer to Fig. 7-1]
1. Examine all parts for signs of wear or damage, replace as necessary.
2. Install the transducer O-ring (5) on the transducer assembly (26). The
O-ring (5) is placed below (process side) the Teflon backup ring on the
transducer.
3. Install the transducer (26) and base plate (27), securing it with two
screws (3) tightened to 15 in/lbs.
Note: The orifice can easily become clogged with skin or other foreign
matter during assembly. Do not touch the orifice with the bare hand
during installation. Use rubber gloves, finger cotts or pliers to start the
orifice in the body.