Flow Measurement of water

[vik1501]

How do I measure flow rate of water flowing in a pipe of 10 mm dia and flow rate between 40 to 75 litres per hour. The circuit should be capable of an accuracy of 2%. :?:

Any help in terms of proven design, links is the most welcome

 

[Chippie]

you could insert a turbine flow meter into the pipe and measure the pulse rate generated........I dont know of a non-intrusive method of flow measurement

 

[vik1501]

Thanks Chippie

But I am looking for non-intrusive method. I followed some theory on this and feel that a circuit could be developed ( may a crude one) to measure voltage induced across the water ( being a conductor) if subjected to magnetic field.

But thats the theory ! How do I put it into practice :roll: Has anyone tried before. :?:

 

[Chippie]

Yeah I vaguely remember a company called Kent instruments form years ago who developed a unit called a magflow meter using magnetic priniples.......( maybe if Mechie reads this he may recall too 8) ) but again the magflow unit needs to be inserted into the pipe section......and they were expensive........
I think more thinking time is needed on this one........ :idea:

 

[Nilo]

I saw my father once developing a liquid flow sensor, by that time was not water, but gasoline.
He was trying to measure the car gas consuption, you know, 20 years ago there was no comnputers on board like today.
He just used a differential temperature measurement method, that was nothing more than insert a PTC(or NTC) inside the pipe to be under flow and another also inside the pipe but just in contact with the fuild.
When no flow accured, both PTC were under same temperature and the differential between both was zero. When one of then as under flow, the heat was extract from it, cooled much more than the other and now the differential between both was enouth and proportional to measure the flow intensity.
I'm not sure how precise is this method.

Note: My father gave up of this project later, not sure why :roll:

 

[tansis]

Merry xmas all, there is a way of doing it by non intrusive method.
Unfortunatly I'm away from my reference books at the moment visiting,
vaugley recall something about a Swiss firm making clip on flow sensors that used ultrasonics (doppler shift) to detect the speed of flow..
Will post more when i get back home.

ps

Happy New Year!!!!

 

[stevez]

There are lots of ways to measure the flow of fluids, water included, that are more or less non-intrusive. For ideas I'd look at manufacturer's websites for ideas. Process flow measurement, flow measurement are similar key words. Usually there's a brief description of the principle(s) that apply. Some use doppler shift. Others use vortex shedding. Lots of work has been done in this area. Some manufacturers have engineering publications that help explain things nicely. So much has been done in this area that it's hard to know where to begin.