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Chapter 6. MAINTENANCE AND TROUBLESHOOTING
(5) Supplying air pressure to the flowmeter and inside of the pipe, make sure that
the instantaneous flow rate shows zero when there is no flow.
(6) Be sure that the air does not leak.
(7) After replacement, enter the replacement date in the space
marked “Date” at the bottom of the unit change label, and
attach the label to the MCF.
Handling Precautions
• The measurement accuracy is ±5 %FS ±1 digit after the measurement
module is replaced with a new one.
• When replacing an RS-485 communications model with a 4 to 20 mA
output model, or vice versa, make sure that there are no wiring errors
before turning on the MCF, in order to protect the connected equip-
ment from damage.
Note
• Flow path identifier.
The flow path identifier is a property of the main path. It refers to the diver-
sion ratio adjustment of the main path. The flow path identifiers 0 to 2 corre-
spond to diversion ratio adjustments 0 to 2. If the flow path identifier is reg-
istered in the measurement module in maintenance mode, the MCF can
adjust the output for the properties of the main path. Therefore the MCF is
able to maintain accuracy.
■ Troubleshooting
● Remedy for abnormal phenomena
Phenomenon Remedy
The display does not indicate anything. • Check that the supplied power and polarity are correct.
• Check that the connector is connected correctly.
Shutting the front and back valves of the • Check for air leaks
MCF, etc., the actual flow rate should be • Check that wiring is correct.
zero, but the flow rate display does not • When the MCF is mounted on a horizontal pipe and the display unit
indicate zero. faces the side, zero point drift may be caused by the mounting
direction. Set the low flow cutoff to 5 %FS.
• If the MCF is mounted where the ambient temperature or the
temperature of the measured gas fluctuates widely, the MCF might
detect convection inside the pipe as a flow. Try measuring after the
temperature stabilizes.
Measurement error has increased and • Check for air leaks.
exceeds the accuracy specifications. • Check if foreign matter is stuck on the main path orifices. If so, remove
it.
• After detaching the measurement module from the main path, check if
foreign matter is present or stuck on the bypass inlet/outlet of the main
path. If so, blow it off with compressed air.
• After detaching the measurement module from the main path, check if
the internal filter is stained. If so, clean it.
• Check if foreign substances such as dust or oil are present on the pipe
or the connection port of the MCF. If so, ask Azbil Corporation for repair.
• Check that the wiring is correct.
• Check if the flow fluctuates widely, or if it greatly exceeds the
measurable limit.
• Check if there is a pulsation source.
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