3-22
Brooks
®
Models 5964, 5850EM
Section 3 Operation
Installation and Operation Manual
X-TMF-5964-5850EM-MFC-eng
Part Number: 541B121AHG
November, 2008
Note: The voltage at TP2 can range from -10 to +3 Volts. It is
recommended, however, that this voltage stay between -2.5 and
+2.5 Volts for proper operation. If the recommended voltage range is
exceeded, the desired accuracy and/or signal stability may not be
achieved. If one of the limits is reached, check the restrictor sizing in
Section 4-7.
3-8 Response Adjustment
This section describes the procedure for step response adjustment. For
enhanced response PC Boards (5 potentiometers) follow either one of the
enhanced response procedures. For standard response PC Boards
(4 potentiometers) follow either one of the standard response procedures.
Two methods of adjusting the step response on the enhanced or standard
response PC boards of the Model 5964/5850EM mass flow controller can
be used.
Adjustment #1 describes a method that will get the step response close to
optimum quickly and without any flow measuring equipment. This method
should be used when the response time of the flow controller is not critical
to overall system performance.
Adjustment #2 describes a method that will allow adjustment of your Model
5964/5850EM mass flow controller to optimum step response
performance. This method is the preferred way to adjust the step
response.
Adjustment of the response circuit will not affect the accuracy of the flow
controller as adjusted in Section 3-7.
Note: The output voltage shown in Figure 3-14 is based on a controller
equipped with an elastomeric seat. For a metal valve seat a positive offset
up to 400 mV can be expected for a zero command.
Enhanced Response PC Board Adjustment #1
(specification not guaranteed)
Note: This procedure requires an oscilloscope, chart recorder or a DVM -
with a sample speed of three samples, or greater, per second to monitor
the rate of change of the output signal.
a. Set the command potentiometer for 100% of flow (5.000 V) and wait
about 30 seconds for the flow output signal to stabilize.
b. Step the command signal to zero percent or activate valve override
closed to stop the flow. Observe the flow signal output as it decays.
c. The behavior of the flow signal during this transition between 100% and
zero percent flow indicates the adjustment required of the anticipate
potentiometer. Refer to Figure 3-14.
