Brooks Instrument 5851EM - Manual (Page 35)

3-9
Brooks ® Models 5965, 5851EM
Section 3 Operation Installation and Operation Manual
X-TMF-5965-5851EM-MFC-eng
Part Number: 541B122AAG
September, 2009
Note: The voltage at TP1 is -100 times the output voltage (+100 times
for Current l/O Version) of the sensor. This voltage can range from -1.2
to -12 Volts (+1.2 to 12 Volts for the Current l/O Version), however, it is
recommended that this voltage stay between -2.0 and -9.0 (+2 and +9
for Current l/O Version) Volts for proper operation. lf the recommended
voltage range exceeds the desired range, accuracy and/or signal
stability may not be achieved. lf one of the limits is reached, check the
restrictor and orifice sizing procedures. Refer to Sections 4-5 and 4-6
respectively.
g. Set the command potentiometer for zero percent of flow. Connect the
DVM positive lead to flow signaloutput (Terminal 3 Card Edge,
Pin 2 D-Connector) and the negative lead to TP4. Readjust the zero
potentiometer for an output of zero mV +2 mV as necessary.
h. Set the command potentiometer for 50% of flow (2.500 V) and measure
the flow rate. Calculate the error as a percentage of full scale.
Example:
What is the percent of full scale error when full scale flow rate is equal
to 100 slpm?
Measured flow rate = 48.5 slpm
Desired flow rate = 50.0 slpm
i. Calculate theTP2 correction voltage:
(error recorded in Step h) x 0.450 Volts
Example:
Error = -1.5%
TP2 correction voltage = -1.5 x 0.450 = -0.675 Volts
NewTP2 voltage = zero volts + (-0.675) = -0.675 Volts
j. Set the command potentiometer for 100% flow (5.000 V). Connect the
DVM positive lead to TP2 and the negative lead to TP4.
k. Adjust the linearity potentiometer for an output equal to the new
calculated TP2 voltage.
l. Repeat Steps f, g and h.
1. lf the error recorded in step h is less than 0.5%, then the calibration
procedure is complete.
2. lf the error is greater than 0.5%, set the command potentiometer for
100% (5.000 V). Connect the DVM positive lead to TP2 (linearity
voltage) and the negative lead to TP4 (circuit common). Calculate a
newTP2 voltage as follows: