Siphon Protection on Double-Wall AST

[vtmechanical]

I am designing a vertical above ground storage tank installation for diesel fuel, and all connections are made at the top of the tank. I currently have an anti-siphon valve located at the top of the suction line (above the liquid level of the tank) to protect the portion of suction line which is below the liquid level from a possible siphon.

For anti-siphon protection of the fill line, I have a check valve located in the fill line at a point above the tank. The pump is located below the tank's liquid level (discharge is approximately 1 foot above grade) and has a check valve near the pump outlet. My client thinks the check valve at the pump eliminates the need for the check valve above the tank. I interpret the need for an anti-siphon device to mean that the anti-siphon device should be located above the liquid level of the tank. My code reference is International Fire Code 3404.2.9.6.10. Does anyone have any advice on where the anti-siphon device should be located? Thanks!

 

[BigInch]

It should be located above the highest liquid level. Should the line leak, break, or any flanges separate between the check's outlet and the tank, siphoning from the tank could be initiated under the right conditions. That unprotected pipe length should minimized, hence it would make sense to put the check above the tank's Hi-Hi liquid level.

"We have a leadership style that is too directive and doesn't listen sufficiently well. The top of the organisation doesn't listen sufficiently to what the bottom is saying." Tony Hayward CEO BP
"Being GREEN isn't easy." Kermit

http://www.youtube.com/watch?v=hpiIWMWWVco

http://virtualpipeline.spaces.liv

 

[vtmechanical]

That makes sense to me too. Thanks for the confirmation!

 

[BigInch]

VT,

On second thought, or maybe I wasn't thinking and this is my first thought, lets be sure about what we're talking about here,

check valve, as in simple one-way flow, or

anti-siphon check valve, like for maintaining simple one-way flow, or an anti-siphon valve like this,

http://www.commercialfuelsolutions.co.uk/downloads/manuals/anti_siphon_valve.pdf

"We have a leadership style that is too directive and doesn't listen sufficiently well. The top of the organisation doesn't listen sufficiently to what the bottom is saying." Tony Hayward CEO BP
"Being GREEN isn't easy." Kermit

http://www.youtube.com/watch?v=hpiIWMWWVco

http://virtualpipeline.spaces.liv

 

[BigInch]

and .. I think you'll probably need to post a diagram eventually, so it could help if you make one now and post it before we go further.

"We have a leadership style that is too directive and doesn't listen sufficiently well. The top of the organisation doesn't listen sufficiently to what the bottom is saying." Tony Hayward CEO BP
"Being GREEN isn't easy." Kermit

http://www.youtube.com/watch?v=hpiIWMWWVco

http://virtualpipeline.spaces.liv

 

[BigInch]

There are also these types of anti-siphon valves,

http://www.myboatsgear.com/featured_product/vented loops.asp

"We have a leadership style that is too directive and doesn't listen sufficiently well. The top of the organisation doesn't listen sufficiently to what the bottom is saying." Tony Hayward CEO BP
"Being GREEN isn't easy." Kermit

http://www.youtube.com/watch?v=hpiIWMWWVco

http://virtualpipeline.spaces.liv