Flow meters are such easy to break
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This post was last edited by evanlei on 2016-11-27 00:28. A few days ago I bought a flow meter of the turbine type, which generates about 58 pulses per second. It worked fine during testing. Today I connected it to control the output; after setting everything up and trying to run it, there was no signal output from the signal terminal. I tested it several times, but still no output. Later, I feared it might be a programming issue – perhaps something related to the counters in the PLC and dual coils – so I wrote another very simple program, but that didn’t work either. I then tried reconnecting the wires to the signal output terminals, fearing it could be an interference problem, but that also didn’t solve the issue. It’s highly likely that the flow meter is broken. I took it apart and blew air into it – it rotated, but no signal was generated. When I inspected the internal circuitry, I found that the chips had been worn away; moreover, the circuit itself was very simple. After spending several hours on it, I lost interest in further investigation and will contact the manufacturer at work. Additionally, the signal output of this flow meter is at a high level when there is no flow, around DC 21V; when flow is present, a regular multimeter cannot detect it. I’m not sure whether this voltage level is normal.
It’s the one that rotates 540 degrees
The turbine flowmeter used by the poster is also a flowmeter of mechanical structure; due to its simple manufacturing process, there are many manufacturers in China, and the quality of these products varies greatly. The service life cannot be guaranteed at all; due to its mechanical structure, the main problem is that its accuracy deteriorates over time. It basically needs to be taken apart and recalibrated every year, resulting in low procurement costs but high operational costs.
When in motion, do you use the DC setting or the AC setting? Theoretically, the value should be visible in AC mode.
Yes, it’s the mechanical structure that’s a concern, but what can be done? Foreign brands are too expensive
I used the DC setting; next time I’ll try using the AC setting. It seems I also have a frequency meter, so I’ll give that a try as well
I really don’t dare to use a turbine – if you don’t use it properly, the blades will be destroyed.
So, what kind of flow meter do you usually use?
Do not use a digital multimeter; a pointer-type one must be used
Use a target flow meter – it is resistant to vibrations and clogging