3-10
Brooks
®
Models 5965, 5851EM
Section 3 Operation
Installation and Operation Manual
X-TMF-5965-5851EM-MFC-eng
Part Number: 541B122AAG
September, 2009
Example:
Controller error = 0.7%
Measured TP2 voltage = -0.567 Volts
TP2 correction = 0.7 x 0.450 = 0.315 Volts
New TP2 correction = 0.315 + (-0.567) = -0.252 Volts
Adjust the linearity potentiometer for an output equal to the new TP2
voltage and then repeat Steps f, g and h.
Note:The voltage at TP2 can range from -10 to +3. It is recommended
however, that this voltage stay between -2.5 and +2.5 Volts for proper
operation. lf the recommended voltage range is exceeded, the desired
accuracy and/or signal stability may not be achieved. lf one of the limits is
reached, check the restrictor sizing (refer to Section 4-6).
3-5 Response
Two methods of adjusting the step response of the Model 5965/5851EM
mass flow controllers 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
5965/5851EM mass flow controller to optimum step response
performance. This method is the preferred way to adjust the step
response. Adjustment of the fast response circuit will not affect the
accuracy of the flow controller as adjusted in Section 3-4.
Response 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 45 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.
