Brooks Instrument 5850EM - Manual (Page 43)

3-19
Brooks ® Models 5964, 5850EM
Section 3 Operation Installation and Operation Manual
X-TMF-5964-5850EM-MFC-eng
Part Number: 541B121AHG
November, 2008
Adjust the span potentiometer until the TP1 to TP0 (sensor voltage) is
equal to the value calculated above. Recheck the flow rate after the
flow is stable (at least two minutes). Repeat this step until the measured
flow rate is within specification. When the flow rate is within specifica-
tion, record the sensor voltage and proceed to Step h.
Note: The TP1 to TP0 (sensor voltage) can range from about 12 mV to
about 120 mV. However, it is recommended that this voltage stay
between 20 mV and 90 mV 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 orifice
and restrictor sizing using the procedures given in Sections 4-6 and 4-7
respectively.
h. Set the linearity jumper by adjusting the command potentiometer for
50% flow (2.500 V). Allow at least two minutes for the flow to fully
stabilize. Read the flow rate. Calculate the error using the following
equation:
Record the error:
If the error is positive (too much flow), the linearity jumper must be in
the (a) position (negative TP2 voltage).
If the error is negative (too little flow), the linearity jumper must be in the
(b) position (positive TP2 voltage).
i. Measure the linearity voltage by setting the command potentiometer to
100% flow (5.000 V) with the DVM positive lead connected to TP2 and
the negative lead connected to TP4. The proper full scale linearity
voltage can be calculated using the following equation:
Note: Error = The error calculated in Step h.
Adjust the linearity potentiometer until the voltage at TP2 equals the
value calculated above.
k. Readjust the span by allowing the flowrate to stabilize at 100% for at
least 30 seconds. Connect the DVM positive lead to TP1 and
thenegative lead to TP0. Adjust the span potentiometer until the sensor
voltage (TP1 to TP0) equals the sensor voltage measured in Step g.
l. Check the calibration by rechecking zero and adjusting if necessary.
Check the flow rate accuracy at 25, 50, 75 and 100% command values.
m. Adjust the response characteristics. (Refer to Section 3-8).