Analysis of Scene Problems for Oval Gear Flowmeter

Fault Phenomenon	Cause	Measure	Remarks
Oval gear does not rotate	1. Debris in pipeline 2. Debris in measured liquid 3. Filter damaged Debris enters meter, gear stuck	Disassemble and clean the meter and pipeline; repair the filter
Axial seal coupling leakage	Packing worn or lack of sealing oil	Tighten the gland or replace the packing; add sealing oil
Pointer rotates unstably	Loose pointer or washer; moving parts not flexible	Retighten and eliminate inflexibility
Small flow error too negative (excessive negative error at low flow)	Oval gear contacts measuring chamber wall due to bearing wear or chamber deformation	Replace bearings; repair deformed measuring chamber and gear; ensure flexible rotation; recalibrate after repair
Large error variation	Large flow pulsation or presence of gas	Reduce pulsation or install a gas separator	For 0.2-class flowmeters, the maximum/minimum error shall not exceed ±0.17%
Excessive error but not exceeding ±1%	Service life exceeded or clearance changed after maintenance	Recalibrate and adjust
No signal from transmitter	1. Transmitter block improperly positioned 2. Polarity reversed	Readjust position (move forward/backward/left/right) Reconnect correctly: + to red wire, – to black wire