3-6
Brooks
®
Models 5964, 5850EM
Section 3 Operation
Installation and Operation Manual
X-TMF-5964-5850EM-MFC-eng
Part Number: 541B121AHG
November, 2008
The flow restrictor shown in Figure 3-3 performs a ranging function similar
to a shunt resistor in an electrical ammeter. The restrictor provides a
pressure drop that is linear with flow rate. The sensor tube has the same
linear pressure drop/flow relationship. The ratio of the restrictor flow to the
sensor tube flow remains constant over the range of the meter. Different
restrictors have different pressure drops and produce meters with different
full scale flow rates. The span adjustment, in the electronics, affects the
fine adjustment of the meter's full scale flow.
In addition to the mass flow sensor, the Model 5964/5850EM Mass Flow
Controller has an integral control valve and control circuit as shown in
Figure 3-4. The control circuit senses any difference between the flow
sensor signal and the command input, adjusting the current in the
modulating solenoid valve to increase or decrease the flow.
3-4 Features
Note: All Model 5964/5850EM mass flow controllers/meters are configured
at the factory as ordered and do not require adjustment. The following
section is for reference should installation conditions change. Not all
features are available on all devices.
Refer to Figures 3-5 through 3-9 depending upon the type of printed circuit
board and connector for jumper locations, functions and adjustment
potentiometers.
Note: To obtain access to the jumpers and test points referenced in this
section, the Electronics Cover must be removed. Extract the cover by
removing the three screws and the valve connector. The cover must be
replaced before returning the device to service.
Fast Response
Adjusted by the anticipate potentiometer, and where applicable the
response potentiometer, this circuit, when properly adjusted, allows the
high frequency information contained in the sensor signal to be amplified.
This provides a faster responding flow signal for remote indication and use
by the control valve.
Soft Start
(Refer to Figures 3-10 and 3-11)
This circuit provides a slow injection of the gas as a protection to the
process, particularly those using a volatile or reactive gas. Full gas flow is
achieved in approximately 15 seconds. This is enabled by moving the J2-
Red Jumper on the printed circuit board. Refer to Figures 3-5 through
3-9, as applicable for jumper configurations.
Valve Test Point/Purge
This feature allows the user to monitor a relative control valve voltage
during operation. One terminal of the valve coil is connected to the -15 Vdc
supply, the other terminal is modulated by the electronics. The relative
valve voltage can be measured between circuit common and Pin D of the
card edge version or Pin 7 of the D-Connector version.
