Brooks Instrument 5860i - Manual (Page 21)

3-5
Brooks ® Model 5860 i
Section 3 Operation
Installation and Operation Manual
X-TMF-5860i-MFM-eng
Part Number: 541B110AAG
November, 2008
Example:
What is the percent of full scale error when full scale is equal to 100 sccm?
Measured flow rate = 50.0 sccm
Indicated flow rate = 48.5 sccm
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. 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.
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:
Sensor 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 volts, however, it is
recommended 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. Refer to Section 4-6.