Where should I put this valve?

[AgSilver]

I'm trying to put a 3-way valve somewhere.

1. The current valve is positioned like an upside down T. Normal operation has water coming vertically down and to the right side. Blowdown mode has water coming from the left side to the right side.

2. Another engineer conceptualized it differently. He saw it as a T on the side. Normal operation has water coming down vertically and straight down. Blowdown mode has water coming from the side and down.

Is one design better than the other? I can only think of the following reasons:
1. pressure losses are higher in the first case, and doing this for normal operation isn't as energy efficient.
2. stronger forces acting on the valve due to the 90o bend wears down the valve quicker (potential leak?)

 

[zdas04]

I don't know who's 3-way valve you're using, but every one I've ever used has a 90[%deg;] hole in the stem. One position connects the base of the tee with the left and the other position connects the base of the tee with the right. I don't know how I would design a 3-way valve that connects one branch to either the base or the other branch.

If it is doable, then you would want the most common flow path to be connected to the two branches for the resons you stated.

David

 

[europipe]

David, they exist, very normal 3-way ballvalves.
AgSilver, I think normal flow should go straight.
1: You are right;
2: I think this is neglectable.

Greetings

 

[zdas04]

My mind was hung up on the "L" configuration valve. A quick look at [link (

http://en.wikipedia.org/wiki/Ball_valve#immutable_link_3-way_from_Valve

]Wikipedia[/url] set me straight. I see how a "T" configuration works now.

David

 

[AgSilver]

The thing is the water has to go to the right eventually, so even if normal operation is straigh through the valve, eventually it will still have to hit a 90o elbow.

Still, I have a feeling that losses are higher in the case where the elbow is built into the valve compared to the case with a straight-thru valve and an elbow after.

 

[Owlish48]

Quite right, AgSilver - the 3-way valve needs to be straight-thru in normal operation. When it is acting as a 90deg elbow, consider it as at very best a branch-flow tee (more likely a 1-cut miter elbow), while your pipe fitting will likely be a long-radius elbow, with much less pressure drop.