1999 by McCrometer/Printed in U.S.A. 2-99/Lit #: 24509-90 Rev 1.0
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SYMPTOM AREA POSSIBLE PROBLEM / SOLUTION
Transmitter No power to transmitter.
No signal
(0 mA) Transmitter Transmitter not wired correctly. Perform continuity check on wiring.
Negative signal
(< 0 mA) Transmitter Transmitter wires are reversed.
V-Cone V-Cone installed backwards, with gauge lines attached as marked. In this
case, the high pressure tap would be sensing a lower pressure than the low
pressure tap. This negative DP would force the signal below 4 mA.
Gauge
lines Gauge lines are reversed. Transmitter sees more pressure on low side than
high side. Check “H” and “L” marks on V-Cone and transmitter.
Low signal
(<4 mA)
Transmitter Transmitter is malfunctioning. Some transmitters will send a specified
mA signal when a malfunction occurs. This can be set to low values, such
as 3.8 mA, or high values, such as 20.1 mA.
V-Cone Meter has been damaged. Remove meter and visually inspect.
V-Cone No flow in pipeline. Check other system locations to verify flow through
the meter. The meter could be under pressure but still have no flow.
Manifold Manifold / gauge lines closed or blocked. Ensure valves and lines are
open. If fluid is safe, open vent valves on transmitter to verify pressure in
the gauge lines.
Zero signal
(4 mA)
Transmitter Transmitter is check mode. Some transmitters allow for system checks by
forcing the signal to 4 or 20 mA. Vent low side of transmitter to ensure
the signal responds to pressure changes.
V-Cone Process conditions do not match actual conditions. Contact McCrometer
or your sales representative to recalculate using the correct process
conditions.
V-Cone Wrong meter. Verify serial numbers on meters to ensure correct
specifications. Sometimes two meters are interchanged. Remember each
V-Cone has a unique flow coefficient.
Gauge
lines Foreign material trapped in gauge lines. Dirt and sediment can settle into
the gauge lines. If the fluid is safe, vent the gauge lines and inspect for
spurts of solids, gasses, or liquids (whichever should not be there). If the
fluid is not safe, open the center manifold valve for several minutes under
high DP. Close the valve and compare the signal level to before. In a
horizontal, liquid application, install the meter with the taps on the sides of
the pipe (3 or 9 o’clock) For a horizontal, gas application, install at top or
sides of the pipe (12, 3, or 9 o’clock).
Flow
computer Flow calculations are in error. Use loop calibrator and apply 4, 12, and 20
mA to computer / system. Each of these points should correlate with the
V-Cone sizing information.
Wrong signal –
high or low
Flow
computer mA signal is read incorrectly. Apply a known current to the loop and read
the raw signal in the computer. Most computers allow the user to see the
mA signal directly.
