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5
OPERATION
Once the meter is installed, the regulating valve should be opened slowly. The fluid flow will
move the float which, by means of magnetic coupling, moves the indicating needle.
Any variations of working conditions with respect to those when calibrated can induce
reading errors. The calibration working conditions are indicated on the instrument's
dataplate.
5.1
Gas flow measurement
The working pressure and temperature are of maximum importance for correct gas
measurement as they directly affect the scale readings.
For example, if a meter is calibrated at 2 bar gauge and the working pressure is 1 bar gauge
there will be an error of about 22%.
In the same way, if working temperature does not match calibrating temperature, errors will
be induced in the flow rate readings.
In applications of gas flow measurement where the calibrating pressure of the instrument
corresponds to the inlet pressure, being higher than the atmospheric pressure, the
regulating valve must be installed downstream of the flowmeter. Thus, it is ensured that the
instrument works at calibrating pressure and a back pressure that keeps the float in
equilibrium is obtained.
The flow should be adjusted by means of the regulating valve, while keeping the shut off
valve fully open.
REGULATING VALVE
SHUT OFF VALVE
NOTE:
Scheme
measurement applications with a pressure
higher than atmospheric. For gases at
atmospheric pressure, turn valves upside
down.
9
valid
for
gas
flow
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