Bronkhorst Mass Flow - Manual (Page 26)

BRONKHORST HIGH-TECH B.V.
4.9 Calibration procedure
All instruments are factory calibrated. This procedure is for recalibration or range changing only.
Calibration of flow / pressure meters / controllers requires the use of accurate digital volt or current meters,
and an accurate calibration device.
General procedure:
a) Apply power to the system and allow approx. 30 minutes for the instrument to warm up and stabilize.
b) Check system on operation.
c) Remove cover during adjustment.
d) Connect digital meter to the output signal.
e) Adjust potmeter ‘L’ till 0% flow/pressure reads 0.010 Vdc output, while disconnecting fluid supply. In
case of an absolute pressure sensor, apply vacuum to the system during adjustment.
f) Adjust potmeter ‘H’ till 100% flow/pressure reads 5.000 Vdc output.
g) Adjust potmeter ‘M’ till 50% flow reads 2.500 Vdc output (not applicable to pressure meters).
h) Repeat steps ‘e’ thru ‘g’ till the deviation between the adjusted and desired values are smaller than the
F.S. accuracy needed.
Notes:
a) In case of other F.S. signal levels, recalculate the 0.010, 2.500 and 5.000 Vdc levels belonging to the 0,
50 and 100% points.
b) Potmeters ‘H’ and ‘M’ can be adjusted without shifting the ‘L’ adjustment.
c) Adjusting potmeter ‘L’ automatically results in a corresponding shift in the positions of potmeters ‘H’ and
‘M’.
d) Potmeter ‘M’ can be adjusted without shifting the positions of potmeters ‘L’ and ‘H’.
e) For the positions of the potmeters consult the instrument specific enclosure.
page 26 9.17.001