Non-intrusive Flow Sensors

[ziptron]

Hello Everyone,

I have a random question for everyone, am looking for flow sensors that can be placed on the outside of a pipe so that I can measure flow within non-intrusively... Something similar to this:

http://www.globalw.com/products/fm500.html#Options

However, I do not want to spend $400-$500 because I do not need such accuracy ,and I need A LOT of them. Also, I do not want to spend so much money because I am looking for something that will detect flow, I do not necessarily need to actually measure the flow. I'd need to detect flow of at least 0.5 GPM on a 0.5 inch. pipe.

If I must go with such a doppler effect setup, I would be willing to manufacture my own electronics to power/detect the Doppler sensors, but I do not know where to find the sensors. Any ideas..

Any input from from anyone regarding this project be would most helpful.

Overall, I am not set on the above doppler sensors... All I need is a way to non-destructively measure flow in a 0.5 inch. pipe and I need to measure flow of around 0.5 GPM or less. Is there such a way?

Thanks!

 

[MikeHalloran]

http://www.gemssensors.com/en/Products/Flow/Flow-Switches/FS-600 No-Moving-parts

Mike Halloran
Pembroke Pines, FL, USA

 

[ziptron]

Thanks Mike,

Gems looks like a good website, but I was hoping that I could do this without opening up the pipe. I'd love to measure from the outside.

 

[MikeHalloran]

If you study how the GEMs thermal switch works, you'll understand that you could do the same thing on the exterior of ordinary pipe, at the expense of response time, and development cost.

The virtue of implementing a sensor as/in a pipe fitting is that when it fails, it can be replaced quickly by relatively low cost tradesmen. The alternative to that is that _you_ will be out there on some winter night reconstructing your sensor assembly.



Mike Halloran
Pembroke Pines, FL, USA

 

[ziptron]

I imagine I would sacrifice not just response time but flow accuracy as well. Having a sensor directly in the water may be orders of magnitude more accurate than having it on a pipe.. but, what do I know. Could work.. very interesting concept. Do you know if this is commonly done?

 

[LittleInch]

The two ways I know to do this externally are, as you've found - ultrasonic transducers and also mag flow sensors. The expensive bit is the sensor and the electronics to work it all out. Not expensive in the grand scheme of things, but probably more than you want.

it's probably worth talking to a couple of vendors like panametrics, fischer, rosemount and see what they have.

However the gem sensors look very good - I'd not come across them before, but they look like what you want, but inside a unit. Maybe someone does one which clamps on and measures flow through the tube wall - not very accurate, but might work.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[MikeHalloran]

Calorimetric flow sensors and flow meters are old and stable technology, not as zoomy as fancier technologies, and not as expensive, so the marketing budget is also smaller. The response time is proportional to the mass, so in smaller sizes they can be quite satisfactory.

GEMS also makes a paddle type sensor that is used on yacht engines to detect loss of coolant flow. Again, it's packaged in a pipe fitting for convenience. Yacht engines are _very_ expensive, and yacht owners are _very_ excitable (trust me on that), and it meets their needs for reliability and low cost.

I know you've got your heart set on some magical strap-on, but preparation of the pipe's outside surface and fitting the sensor may take more time than just inserting a tee. Talk to your pipefitters about that.



Mike Halloran
Pembroke Pines, FL, USA

 

[MartinLe]

"... but preparation of the pipe's outside surface and fitting the sensor may take more time than just inserting a tee. Talk to your pipefitters about that."

Maybe also talk about tapping clamps.