5. To eliminate air bubbles in the MVT, manifold and legs connecting them to the meter, fill the legs with fluid. Choose
a fluid that is safe for the environment and stable when depressurized.
Important If the process fluid does not present an environmental risk and is stable when depressurized, it
may be used to bleed air from the lines. If the process fluid can contaminate the environment or is
highly volatile when depressurized as with liquefied gases, a different seal fluid should be used to
fill the legs. An ideal seal fluid is one that does not dissolve in the process fluid.
6. If
process fluid
is to be used, bleed air from the lines as follows. If a different seal fluid is to be used, proceed to step
8.
a. Make sure the shut-off valves in the tubing near the meter pressure taps are closed, and the meter is filled with
process fluid.
b. Open the equalizer and bypass/block valves on the block manifold. Make sure the vent valve is closed.
c. Open one of the shut-off valves near the meter.
d. Slowly loosen the corresponding vent screw on the MVT, and throttle the rate of flow from the vent with the
shut-off valve.
e. When air bubbles are no longer visible around the MVT vent, tighten the MVT vent screw.
f. Repeat steps 7a through 7e for the other leg.
g. Proceed to step 9.
7. If a fluid
other than the process fluid
is to be used, bleed air from the lines as follows:
a. Make sure the shut-off valves in the tubing near the pressure taps are open.
b. Open the equalizer and bypass/block valves on the block manifold. Ensure the vent valve is closed.
c. Remove the vent screw from one side of the MVT and insert a fitting to allow connection of a hand pump or
funnel. If a funnel is used, attach a length of Tygon tubing long enough to elevate the funnel well above the
meter pressure taps to force the fluid up the legs.
d. Connect a hand pump or funnel to the fitting.
e. Estimate the amount of fill fluid required to fill the tubing and push any air bubbles into the meter.
f. Pour fill liquid into the funnel, tapping the tubing occasionally to dislodge any bubbles.
g. When the leg is full of fluid, remove the fitting from the MVT vent and quickly replace the vent screw and
tighten.
h. Repeat steps 8a through 8g for the other leg.
8. Follow guidelines outlined in MVT manual to perform a manifold leak test.
9. Wire outputs or COM connections from the MVT to the inputs or COM connections on the back of the QRATE
Scanner 3300.
10. Verify the zero offset (and other calibration points), if required.
CAUTION Do not put the MVT into operation until the valves are positioned properly so that pressure is sup-
plied to both sides of the transducer.
46
Section 2
QRATE Scanner 3300 integrated control flow computer
