Brooks Instrument 5861i - Manual (Page 21)

3-5
Installation and Operation Manual
X-TMF-5861i-MFC-eng
Part Number: 541B111AAG
November, 2008
Brooks ® Model 5861 i
Section 3 Operation
f. Shut off the flow. Connect the DVM positive lead to flow signal output
(pin 2 D-connector) and the negative lead to TP4. Readjust the zero
potentiometer for an output of 0mV±2mV as necessary.
g. Adjust flow rate for a flow signal output of 50% (2.500V) and mea-
sure the flow rate. Calculate the error as a percentage of full scale.
Note: indicated flow rate can be found using the following formula:
Example:
What is the percent of full scale error when full scale is equal to 50 slpm?
Measured flow rate = 25.75 slpm
Indicated flow rate = 25 slpm
h. Calculate the TP2 correction voltage:
(error recorded in step g) x -0.450 volts
Example:
Error = -1.5%
TP2 correction voltage = -1.5 x- 0.450 = 0.675 volts
New TP2 voltage = 0 volts + (0.675) = 0.675 volts
i. Adjust flow rate for a flow signal output of 100% (5.000V). Connect
the DVM positive lead to TP2 and the negative lead to TP4.
j. Adjust the linearity potentiometer for an output equal to the new
calculated TP2 voltage.
Note: the output signal should be kept at
5.000 V during this adjustment.
This can be done by varying the actual flowrate.
k. Repeat steps d, e, f and g.
1. If the error recorded in step g is less than 0.5%, then the calibration
procedure is complete.
2. If the error is greater than 0.5% set the flow rate for a flow signal
output of 100% (5.000V). Connect the DVM positive lead to TP2
(linearity voltage) and the negative lead to TP4 (circuit common).
Calculate a new TP2 voltage as follows:
Example:
Full scale error = 0.7% (found in step g)
Measured TP2 voltage = -0.567 volts
TP2 correction = 0.7 x -0.450 = -0.315 volts
New TP2 correction = -0.315 + (-0.567) = -0.882 volts