Brooks Instrument Mfi Series - Manual (Page 22)

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Brooks ® Mf Series
Section 2 Installation Installation and Operation Manual
X-TMF-Mfi-Mfx-eng
Part Number: 541B074AAG
August, 2009
Recommended installation procedures:
a. The Mf Series instrument should be located in an environment relatively
free from shock and vibration.
b. Leave sufficient room for access to the electrical components.
c. Install in such a manner that permits easy removal if the instrument
requires cleaning.
When used with a reactive (sometimes toxic) gas, contamination
or corrosion may occur as a result of plumbing leaks or improper
purging. Plumbing should be checked carefully for leaks and the
controller purged with dry Nitrogen before use.
CAUTION
d. The Mf Series controllers and meters can be installed in any position.
However, mounting orientations other than the original factory calibra-
tion will result in a ±0.5% maximum full scale shift after re-zeroing.
e. When installing controllers with full scale flow rates of 10 slpm or
greater, be aware that sharp abrupt angles in the system piping directly
upstream of the controller may cause a small shift in accuracy. If
possible, have at least ten pipe diameters of straight tubing upstream of
the Mf devices.
Note: The control valve in the Mf controller provides precision control and
is not designed for positive shut-off. If positive shut-off is required, it is
recommended that a separate shut-off valve be installed in-line.
Special considerations to be taken when installing the Mf53 MFC:
The Model Mf53 has a valve design that is different from standard low flow
Brooks TMFC’s. The Mf53 consists of a dual stage, pilot operated valve.
The pilot valve (located on top of the MFC) controls a differential pressure
across the main valve which, in turn controls the flow through the device.
The main valve is a pressure operated valve that utilizes a bellows spring
and diaphragm to control flow. This bellows and diaphragm assembly can
be susceptible to damage by pressure spikes or surges. For this reason, it
is recommended that process line startups are handled with care.
The bellows spring is offered in two levels. A low force for low differential
pressures (delta P < 30psig), and a high force (delta P >30 and <300 psig).
The selection of the bellows spring is mainly determined by the differential
pressure as specified on the customer order. This should reflect your
actual process conditions. The low force bellows consists of a softer
bellows spring which is required to allow flow control at lower differential
pressures.
During startup conditions, when a process line is being pressurized, the