General instrument failure inspection

01 simple judgement of amplifier fault
When there is no special instrument, use the display instrument to observe the signal and sense the signal at the input end of the probe lead of the detection amplifier by hand, so as to roughly judge whether it is the fault of the detection amplifier. If there is a signal reflection, the detection amplifier is basically normal, otherwise, the detection amplifier may be faulty.
02 simple judgement of probe failure
If the instrument has no signal reflection and the detection amplifier has signal reflection, it can be considered that the detection probe may be faulty. Check the quality of the detection probe. The insulation resistance of two signal wires can be measured with a multimeter. When the temperature is lower than 200 ℃, the insulation resistance shall be greater than 2m Ω; When the temperature is higher than 200 ℃, the insulation resistance shall be greater than 10m Ω. If the insulation resistance meets the requirements, the detection probe is basically normal, otherwise there may be a fault.

Routine maintenance
Vortex flowmeter has no movable parts, so it generally does not need frequent maintenance under normal use. When the measured medium is dirty or easy to scale, the inner wall of the flowmeter shall be cleaned regularly. During cleaning, the vortex generator and detection probe shall be protected, and attention shall be paid not to damage its surface and edges. During maintenance, non professionals shall not disassemble all parts at will to avoid damage to the flowmeter. The housing end cover of the detection amplifier shall be properly tightened after wiring commissioning to ensure its tightness. During maintenance and inspection, do not leave liquids and sundries in the shell.

Common system faults and treatment
1. Fault classification
The fault types can be divided into system fault and instrument fault. After a fault occurs, check the system fault first. If no problem is found, check whether it is an instrument fault.

1.  system faults include: incorrect installation and wiring, mismatched caliber, inconsistent flow range, impact of vibration and electromagnetic interference, power supply problems, improper sensitivity adjustment, etc;
   

2.  instrument faults include: detection probe failure, detection amplifier failure, internal short line, table body leakage, etc.
   

2. Common system faults and treatment
01 after power on, there is fluid flow in the pipeline, but there is no signal output.

• check whether the instrument wiring is correct and broken.
  

• check whether the instrument installation direction is correct.

• check whether the flow is lower than the normal flow range.

02 there is no fluid flow in the power on pipeline, but there is signal output.

• check whether the instrument grounding is caused by poor grounding.
  

• check whether the pipeline has strong mechanical vibration.

• check whether there is strong electromagnetic interference in the environment, such as high-power electrical appliances or frequency converters.

• check whether the sensitivity is too high, and adjust the band switch of the amplifier.

03 the fluid flow in the pipeline is stable and meets the flow requirements, but the output changes too much and is unstable.

• interference may be caused by poor grounding.
  

• interference may be caused by excessive pipeline vibration.

• it may be that the sensitivity is too low and there is a missing trigger phenomenon. Just improve the sensitivity.
  

04 the displayed flow is inconsistent with the actual flow, and the error is large.

• the instrument parameters may be set incorrectly.
  

• the measurement error of temperature and pressure instrument may be too large.

• the flow may be lower or higher than the normal flow range.

It may be that the installation does not meet the requirements, such as non concentric installation, obstacles in the pipeline, insufficient straight pipe section, etc.