Brooks Instrument 5860E - Manual (Page 25)

4-3
Installation and Operation Manual
X-TMF-5860E-MFM-eng
Part Number: 541B106AAG
November, 2008
Brooks ® Model 5860E
Section 4 Maintenance
Table 4-1 lists possible malfunctions which may be encountered during
bench troubleshooting.
C. Sensor Troubleshooting
If it is believed the sensor coils are either open or shorted, troubleshoot
using Table 4-2. If any of the steps do not produce the expected results the
sensor assembly is defective and must be replaced. Refer to Section 4-4
for the disassembly and assembly procedures to use when replacing the
sensor.
Note: Do not attempt to disassemble the sensor.
D. Cleaning Procedures
Should the Model 5860E Mass Flow Meter require cleaning due to
deposition, use the following procedures:
1. Remove the unit from the system.
2. Refer to Section 4-4 to disassemble the flowmeter.
3. Use a hemostat or tweezers to push a 0.007" dia. piano wire through
the flow sensor tube to remove any contamination. For best results
push the wire into the downstream opening of the sensor tube. The
sensor tube can be flushed with a non-residuous solvent (Freon
TF® recommended). A hypodermic needle filled with solvent is a
convenient means to accomplish this.
An alternate method for flushing out the sensor is to replace the
restrictor element with a low flow plug restrictor. This plug forces all
the flow through the sensor and may dislodge any obstructions.
Subject the flow meter to a high differential pressure. Pressurizing
the outlet of the flowmeter higher than the inlet may help force the
obstruction upstream and out of the sensor tube.
4. Deposits of silicon dioxide may be removed by soaking the internal
parts in solution of 5% of hydrofluoric acid (5 parts hydrofluoric acid
(HF), 95 parts water (H
2
O)) followed by Freon TF.
5. Sintered type restrictor elements should be replaced as it is not
always possible to adequately remove deposits from them. Wire
mesh and A.C.L.F.E. type restrictor elements can be cleaned in an
ultrasonic bath. Refer to Section 4-7 for the correct restrictor to use.
6. Blow all parts dry with dry Nitrogen and reassemble. Refer to Section
4-4b (assembly).
7. Purge the assembled controller with dry Nitrogen.
8. Perform the calibration procedure in Section 3-4.
9. When the flowmeter is reinstalled 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.