P
AGE
10
Section 7 - Troubleshooting
HM FLOWMETER TROUBLESHOOTING GUIDE
PROBLEM
CAUSE
ACTION
No output or
erratic output
• Failed Probe (no output)
• Probe not seated
• Moisture and/or corrosion
in probe-to extension
cable connector
• Flow rate too low
• Obstructed Rotor
• Incorrect wiring
• Bad cable splice
• No scale factor entered
• Signal interface problem
• Replace Probe
• Check probe: must be threaded to bottom
• Disconnect extension cable at probe for
visual check, dry or clean if required
•
Check meter specification for flow range
• Check rotor (should spin freely)
•
Check manual for correct wiring configuration
• Check color code and continuity integrity
• Check readout device scale factor
• Check signal input specs of receiving device
HT75000
• Incorrect coil resistence
•
Check black/white signal wires for 975Ω
Poor
accuracy/
repeatability
• Air in system
•
Process flow rate out of
meter flow range
• Obstructed Rotor
• Probe not seated
• Poor meter installation
• Poor system hydraulics
• Incorrect scale factor
• Electrical noise
• Changing product
characteristics density
and/or viscosity
• Inaccurate proving
standard
• Operating error – poor
testing method
• Rotor wear
• Damaged housing
• Add air elimination device
•
Check meter specs for flow range info (adjust
flow rate or change-out meter)
• Check rotor (should spin freely)
• Check probe: must be threaded to bottom
• Locate meter in low spot (see installation)
•
Backflow? (Install check valve) Valve closing
time?
• Check: scale factor, K factor and unit of
measure
• Check: shielding, separate signal from AC
wires
• Check: product weight, viscosity, scale
accuracy, control temp. Multiple products?
•
Verify accuracy of proving standard (vessel/
scale)
• Observe test procedure
•
•
Remove and inspect (figure: 6.4)
•
Remove and inspect (figure: 6.5)
