Has anyone used V-cone flow meters for flow measurements of clean water in large diameter (24") pipes?

 

Yes, I've seen several. Haven't done it myself, but there should be no reason why it wouldn't work as specified.

Here's a link to a case study on McCrometer's website that talks about a 36 inch steam line with a v-cone. I'm sure McCrometer can give you lots more references.

Good luck,

Walt Boyes
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630-639-7090
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I have not, although I've used V cone on numerous pipes 4" or less.

I'd sure be looking at external clamp-on ultrasonics as an alternative if I were doing it on a 24" pipe for clean water.

Carl

 

I agree, with some warnings...

If the pipe is already installed, using a clamp-on transit time flowmeter is the optimal solution unless you need the ability to prove its calibration. IT WILL cost a whole lot less than any other solution.

And remember that the transit time meter will require a whole lotta straight run for real accuracy... at least 15 to 20 diameters, if there are no three-dimensional turns in the piping within 100 diameters. If those three dimensional turns exist, you will need well over 100 diameters of straight run, or a flow conditioner like Vortab.

A v-cone will require substantially less straight run. In smaller pipes, it requires none, but in a large diameter pipe, I would expect to see at least 10 diameters, regardless of elbow geometry upstream.

And you'll have to make a hole in the pipe to put the v-cone in.

Walt Boyes
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For a 24" clean water application I would consider a pitot type flow element, e.g. annubar, provided you have a reasonable length of straight run.

Regards,
Roy

 

That's another good solution, and so is the proprietary multiple sensor mag meter insert by Marsh McBirney called the MultiMag. It is a no brainer combination of the physical design of a multiple port Pitot tube replacing the ports with magnetic velocity sensors. Clever idea. MarshMcBirney is now part of McCrometer/Hach/Danaher.

The big problem with these, of course, as you said, Roy, is the reasonable length of straight run. Assuming that's there you're fine.

Now, Emerson's Annubar, and several other multiport pitot tube flowmeters claim the ability to do custom calibrations so they can be installed immediately downstream of elbows, and other flow restrictions.

I've seen it done, and it seems to work, but you pays yer money and you takes yer chance.

Walt Boyes
Editor in Chief
Control and Controlglobal.com
www.controlglobal.com
Mailto:[email protected]
Read my blog SoundOFF!! At www.controlglobal.com/soundoff

 

Depending on the application another good flowmeter for large pipes is a propeller meter (like a boat propeller) these can be supplied in a saddle or weld on format. They are very reliable, in-expensive and don't require much straight run.

I have used many of these from Water Specialties, Oops I see Mccrometer have bought them out. I wonder why?

Regards
Roy

 

There are few important aspect when you select a flow meter like straight length, accuracy & repeatability of measurement & most important on large line size metering is pressure loss. Accuracy requirement has to be well balanced with other factors including energy loss (operating cost) & price of the technology. V-Cone has significant pressure drop & that is nothing but energy lost in measurement as compared to Transit Time Ultrasonic Meter or ANNUBAR or for that matter Insertion Electromagnetic Flow Meter. In today's world energy saved is profit so look at a technology that let you achieve the required accuracy at reasonable price. I would highly recommend using Ultrasonic, Pitot Tube or Insertion Mag Meter provided your application doesn't ask for accuracies better than +/-1% to +/-3% of reading which is easy to get even on shorter straight length flow metering application.