Foot valve

[duika]

Hi guys,

I would like to calculate the loss of head in a 20" foot valve for a velocity of the fluid (water) about 1.2 m/s.

The most important factor are the losses in the screen retainer (i suposse), so should be interesting to know any kind of chart for calculate the losses depending the shape, diameter and the number of the circles of the string.

Thanks in advance.

 

[katmar]

Each make of valve is slightly different from the others. Get the pressure drop vs flowrate chart from the manufacturer of your specific valve. Using a generic method will be more difficult and less accurate.

 

[gustorf]

duika,

as far as I know, the screen retainers are designed to have an open flow area similar to the nominal diameter of the pipe, so their pressure loss is no the most significant item.
The valve itself creates higher pressure losses.
If you install a nozzle check valve, the prssure loss may be as low as 5.5 mbar at 1.2 m/s.
They are non-slamming without dampening and available at

http://www.noreva.de

or hgustorf@noreva.de

 

[BobPE]

Screens are usually designed at a much larger area than the nominal flow area to minimize losses associated with the screen opening themselves. That is why you usually see conical screens or large drum type screens.

I would hope the manufacturer will have the emperical data you need. Just make sure they give you the data for your entire valve system, inclusive of the screen. A lot of times the first level sales reps don't have this info and you need to dig back to corporate engineering. Don't give up until you get the info you need!!!!

BobPE