Water flow sensor overloaded

Thread Starter

meowsoft

Joined Feb 27, 2021
607
I want to use arduino DN32 water flow sensor with only 1-120 L/Min capacity, do you think if I use with more than 120L/Min water flow it will permanently damage water flow sensor ?, or I just temporarily can't read water flow correctly ?
I just need water flow sensor for water leak detection system, when there is no motorized valve open, but water flow is still running, I can suspect for water leak through pipe
What do you think ?

Water flow sensor I bought is like this :
https://www.aliexpress.com/item/1250477149.html
 

Thread Starter

meowsoft

Joined Feb 27, 2021
607
It probably will not die, but become very inaccurate in the over-range.
Yes, I think so, but are you sure ?, seller it's say's it will be permanently damaged but seems incompetence for electronic things
and do you think it will affect accuracy in the long term ? (after over-range)
 

Alec_t

Joined Sep 17, 2013
14,313
Judging by the shape of the flowmeter it would typically have inside it a vaned wheel rotating a magnet past a Hall sensor. Like Bertus, I would wonder about the longevity of the bearings, particularly if asked to handle 240l/min.
 

Reloadron

Joined Jan 15, 2015
7,517
Yes, my system can push about 240 liters per minutes at maximum...
Personally if you want accurate readings I suggest buying a flow sensor which meets your requirements. Also consider the quality of the water you are measuring flow of. Next if you only care about flow rate that's fine but if you ant rate and total then consider not just rate function but totalizer function also in your monitoring system. The reason for a manufacturer specifying a flow range and max pressure is that the stated accuracy or uncertainty is based on those numbers. The sensor you linked to looks to be a paddlewheel type. The paddle is picked up by a hall effect sensor. Flow rates exceeding the published specification simply will not meet specifications. That is why a range is called out. Also cheap sensors have the paddle spin on normally a stainless steel pin. High end sensors actually use bearings with a turbine design as Bertus points out above..

Flow sensors like this also have what is known as a K Factor and that is a constant inside the specified range. Actually the K Factor is normally an average mean. You linked to sensor looks to have a 4.5 K Factor. You use that in your math calculations. The K Factor is the number of pulses per unit of measure be it Liters or US Gallons.

Ron
 
Last edited:

Reloadron

Joined Jan 15, 2015
7,517
Two sensors in parallel?
The only time I have seen flow meters in parallel was when one or the other was removed from service for calibration or in cases where if one failed the other came online. Never gave thought to running two in parallel at the same time. Seems logical.

To the thread starter another consideration is pipe diameter. Normally to avoid flow turbulence you want straight lines into and out of your flow meter. The old rule was 10D and 5D so upstream you want 10 * the pipe diameter and downstream you want 5 * the pipe diameter. I forgot about that earlier. Consult the manufacturer's data sheet or recommendations on flow straighteners.

Ron
 

Kjeldgaard

Joined Apr 7, 2016
476
I had some thoughts about shunting some of the water around the flow sensor at higher consumption, but didn't get around to writing about it.

But my thoughts were something with a suitably large non-return valve in parallel with the flow sensor, so that at low flow all the water will run through the sensor, and when the flow becomes higher the non-return valve will take over more and more water.
 

Reloadron

Joined Jan 15, 2015
7,517
I had some thoughts about shunting some of the water around the flow sensor at higher consumption, but didn't get around to writing about it.

But my thoughts were something with a suitably large non-return valve in parallel with the flow sensor, so that at low flow all the water will run through the sensor, and when the flow becomes higher the non-return valve will take over more and more water.
Yes but if I bypass a flow sensor when I need to know flow then how do I know my flow rate? Then too if the flow rate is not that important why bother to measure it in the first place? Just use a flow sensor more than capable of the anticipated flow rate. So yes, your suggestion is easily enough done but I don't see a benefit.

Ron
 

Kjeldgaard

Joined Apr 7, 2016
476
@Reloadron

I read it as if TS wants to detect leaks on the water supply in the building.

In other words, measurement all the way down at or below 1 liter/min, but had problems with the normal consumption significantly exceeding 120 liters/min.

So my idea is to break the measuring curve, so that up to maybe 2 litres/min has the initial sensitivity of the flow meter and then has lower sensitivity up to maybe 300 litres/min.
 

Reloadron

Joined Jan 15, 2015
7,517
@Reloadron

I read it as if TS wants to detect leaks on the water supply in the building.

In other words, measurement all the way down at or below 1 liter/min, but had problems with the normal consumption significantly exceeding 120 liters/min.

So my idea is to break the measuring curve, so that up to maybe 2 litres/min has the initial sensitivity of the flow meter and then has lower sensitivity up to maybe 300 litres/min.
Then if knowing rate or total is not a big deal yes, an automatic bypass could be used for high demand I guess.

Ron
 
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