Anti-syphon valves

[davidwigler]

I spent some time in the bilge replacing fuel lines and installing a new fuel manifold. I never noticed before but the anti-syphon valves are installed horizontally, parallel to the top of the tanks. I would think to function they would have to be mounted vertically so the little ball would seat without a vacuum. Does anyone know?

 

[jeremyp111]

I'm not sure what the regs are, but mine are installed horizontally too. I've never seen them mounted vertically. Maybe there's a reason for that? I just don't know what it is....

 

[Reel Antsy]

They have a spring and check valve/or ball inside of them. So as long as there is suction drawing up against the spring, it shouldn't matter.

 

[Sandy]

As Reel Antsy says, the A/S check valve is spring loaded and usually require cracking pressure or vacuum in both directions to inhibit siphon out AND drainback, and likely different parameters (on the side of the valve I think George said?) for that in the 2 directions. I also have only seen them horizontally as tank outputs are that position to minimize clearance required & start the fuel line in the right direction without an unneeded hose bend or elbow I'd imagine.

 

[captgoerge]

Its a spring like in a pen you used to take apart in school and a large BB, one way valve. Fuel pump sucks it open.