I am wanting to select a emergency shutoff valve in accident operation.
But I have no idea of the emergency valve. Could you tell me the ways to select the emergency valves and how to choose the type of emergency valve?
I normally see the emergency valve is ball valve. Why?
Thank you in advance.
Full Version: Emergency Valve Selection
With so little information, I can only provide a very general commentary regarding the subject.
Ball valves, like globes and several other types of valves are commonly used as isolation or block valves. This is because they are fairly robust and reasonably priced valves and can provide many years of satisfactory service if properly chosen. My assumption is that you would want quick isolation in the event of an emergency. (That doesn't seem like too much of a stretch.) Ball valves, vis-a-vis, their main competitors the rising stem valves, offer the advantage of being quarter turn valves. Turn the valve handle just 90 degrees and the valve goes from fully open to fully closed. Thus you have the quick and the isolation characteristics in one, low price package.
Why not?
Doug
Ball valves, like globes and several other types of valves are commonly used as isolation or block valves. This is because they are fairly robust and reasonably priced valves and can provide many years of satisfactory service if properly chosen. My assumption is that you would want quick isolation in the event of an emergency. (That doesn't seem like too much of a stretch.) Ball valves, vis-a-vis, their main competitors the rising stem valves, offer the advantage of being quarter turn valves. Turn the valve handle just 90 degrees and the valve goes from fully open to fully closed. Thus you have the quick and the isolation characteristics in one, low price package.
QUOTE (daiweisc @ Oct 18 2007, 06:25 AM) 
Why?
Why not?
Doug
QUOTE (djack77494 @ Oct 18 2007, 12:26 PM)
With so little information, I can only provide a very general commentary regarding the subject.
Ball valves, like globes and several other types of valves are commonly used as isolation or block valves. This is because they are fairly robust and reasonably priced valves and can provide many years of satisfactory service if properly chosen. My assumption is that you would want quick isolation in the event of an emergency. (That doesn't seem like too much of a stretch.) Ball valves, vis-a-vis, their main competitors the rising stem valves, offer the advantage of being quarter turn valves. Turn the valve handle just 90 degrees and the valve goes from fully open to fully closed. Thus you have the quick and the isolation characteristics in one, low price package.
Why not?
Doug
Ball valves, like globes and several other types of valves are commonly used as isolation or block valves. This is because they are fairly robust and reasonably priced valves and can provide many years of satisfactory service if properly chosen. My assumption is that you would want quick isolation in the event of an emergency. (That doesn't seem like too much of a stretch.) Ball valves, vis-a-vis, their main competitors the rising stem valves, offer the advantage of being quarter turn valves. Turn the valve handle just 90 degrees and the valve goes from fully open to fully closed. Thus you have the quick and the isolation characteristics in one, low price package.
QUOTE (daiweisc @ Oct 18 2007, 06:25 AM)
Why?
Why not?
Doug
daiweisc,
Emergency Shutdown Valve (SDV) shall have the following features as minimum :
i) Tie Shut Off (TSO) - minimum leakage
ii) Fast action (Full Open - Full Close) - Emergency demand
iii) Minimum passing - minimize overpressure of LP system and spurious trip
iv) Minimum disturbance / turbulence - minimize unnecessary energy lost
v) Firesafe
vi) Reliable / Maintainable / reasonable cost...
Ball valve as compare to other type of valves (globe, gate, butterfly, plug, etc) meeting the most of above criteria.
i) TSO - Ball valve so far the best (Doug indicated as isolation...)
ii) Fast action - Quarter turn feature required minimum closure time (Doug indicated as quick action)
iii) Minimum passing - Most ball valve present equal% characteristic. 10% valve closure give 20% flow reduction, 20% closure give 50% closure...
iv) Minimum disturbance / turbulence - Reduced Bore (RB) ball valve having hole in the middle would minimize flow direction change and turbulence. Full Bore (FB) ball valve virtually like a pipe- significantly minimize energy lost
v) most ball valve has firesafe feature
vi) History shows ball valve is reliable / maintainable...
I believe beauty of ball valve are more than those i have highlighted. Those who are aware, please drop note here...
Nevertheless, ball valve may not good for certain services such as fluid contain solid, potential polymerization fluid, etc. Those other type of valve such as plug and gate may be used.
JoeWong
Thank you.
I have some idea of emergency valve.
I have some idea of emergency valve.
All,
In additional to above, please read this article for additional features required for a Shutdown Valve.
JoeWong
In additional to above, please read this article for additional features required for a Shutdown Valve.
JoeWong
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