Air release Valve

[PPantha]

Hello,
I need to select the air release valve for one of my Hydropower project penstock pipeline.The length of penstock pipe length downstream of pipe is almost 420m with slope of 41 degree almost and water discharge is 12.26 m3/s with pipe dia 1900 mm. Can you please suggest me the size of air valve ??

 

[bimr]

Air Vent Analysis

Eng Tips

Link

 

[LittleInch]

Can you describe a bit more the conditions at which this valve operates?

Do you really mean an air inlet valve?

The links by bimr cover a lot of potential issues, but I can't figure out what your issue is.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[gerhardl]

PPantha,

Please note that this is not a direct calculation, but a result of an evaluation of your total situation. Both layout, normal process situation, normal filling and emptying and eventual breakdown situations must be considered.

Filling: Must be controlled and in a rate where air can escape 'naturally' or if insufficient by air outlet valves. Normal waterpipe mains calculation/air outlet valve types based on this should be OK

Emptying: For a hydroelectric plant worst case is equipment breakdown. Air inlet, top placed, must in any cases be large enough to avoid collapse from vacuum. Too fast emptying can be caused by false or wrong operation, bottom valves breakdown, other bottom equipment failure, bursting main pipeline or other causes.

The rate/amount of water leaking can vary widely, for instance will a buried pipe probably leak a bit less than an open pipe if it bursts.

Necessary inlet valve size in your case may come out to be in a larger range. I have supplied air inlet valves up to 1000mm in diameter to hydroelectric plants.

A rough estimate can be done as simple as taking the water volume escaping as necessary volume air to be let in by an opening Xmm if the air velocity is a fair 'gas speed normal through pipelines' say 30-90 m/s. Remember air noise level!

(PS: 400-500mm????)