Differential Pressure and Flow Measurement

[jebatty]

I believe it is possible to determine flow by placing a pressure gauge on each side of the circulator, determining the pressure difference, and multiplying by 2.31 to determine pump head. Is this correct? Then use the circulator curve with the determined pump head to determine gpm. Has anyone done this? How close to each side of the circulator do the taps have to be for the pressure gauges?

 

[DaveBP]

Deja vu all over again.

I think Hot Rod just posted this technique in a thread somewhere here in the last week or two.

I don't remember the details, if any.

 

[jebatty]

Missed it. If anyone knows the link, let me know. I did a search back over a year before I did my post and didn't happen to see anything.

EDIT: My member search shows Hot Rod has only one post and it does not deal with this.

 

[stee6043]

What kind of pressure measuring devices are you thinking about using? Without a highly accurate sensor I think this kind of determination of flow rate will be very inaccurate. Just my humble opinion...

 

[in hot water]

I believe it is possible to determine flow by placing a pressure gauge on each side of the circulator, determining the pressure difference, and multiplying by 2.31 to determine pump head. Is this correct? Then use the circulator curve with the determined pump head to determine gpm. Has anyone done this? How close to each side of the circulator do the taps have to be for the pressure gauges?

Yes, use one gauge, the same gauge kf possible to account for any gauge error. Their could be some manufacturing tolerance error in the pump to actual, an engineer pointed out to me 10% on a 5 gpm flow would be 1/2 gpm error, but probably close enough for your needs?

I build a bypass and a small 1/4" ball valve, read one side, valve it off then the other. Some pumps have gauge taps, I think some of the new Grundfos SuperBrute XLs have gauge ports in the flanges.

Grundfos has some neat flow and temperature sensors if you want to keep the device in the system. Most of the solar controllers now accept this sensor input.

http://net.grundfos.com/doc/webnet/directsensors/int/products_vortex.html

hr

 

[DaveBP]

Missed it. If anyone knows the link, let me know. I did a search back over a year before I did my post and didn’t happen to see anything.

It's in this thread, Jim.

https://www.hearth.com/econtent/index.php/forums/viewthread/50189/P0

I found it under his username "in hot water".