Tank Vent ???

[Matt]

hi y'all, can anyone explain to me how the echo or husqvarna tank vents work. the echo are the litle white button looking ones(Part Number: A356000031) or the black rubber sheath looking ones, the husqvarna Part#: 501873101, similar to the black echo. my understanding is as such, they allow venting or vacuum to pass from the vent itself into the tank and not allow vapor or fuel to run back out through it?? so as the tank draws down it creates a vacuum, the vent will open and allow atmosphere to re-enter the tank. but if you turn/tip the machine upside down, and fuel starts to run out the hose towards the vent, the vent will not allow for for spillage cause of its "check valve" or one way valve ability. am i correct or way off. thanks, may seem like a dumb question to most but im having difficulty seein right now. matt

[bobodu]

They are just check valves. They can get dirty and stick open or closed.

[bgsengine]

hi y'all, can anyone explain to me how the echo or husqvarna tank vents work. the echo are the litle white button looking ones(Part Number: A356000031) or the black rubber sheath looking ones, the husqvarna Part#: 501873101, similar to the black echo. my understanding is as such, they allow venting or vacuum to pass from the vent itself into the tank and not allow vapor or fuel to run back out through it?? so as the tank draws down it creates a vacuum, the vent will open and allow atmosphere to re-enter the tank. but if you turn/tip the machine upside down, and fuel starts to run out the hose towards the vent, the vent will not allow for for spillage cause of its "check valve" or one way valve ability. am i correct or way off. thanks, may seem like a dumb question to most but im having difficulty seein right now. matt

You got the gist of it , but they are also required to seal off fuel tank from venting pressure up to a certain level, to the atmosphere, due to EPA emissions regulations (Likewise on machines built after 12/31/2011 fuel lines that are exposed to the atmosphere must be a special non-permeable fuel line.)

Basically they have a "ball and spring" sort of action when it comes to allowing air IN to the tank - just enough tension that the fuel tank MAY draw a vacuum for second or two but never HOLD a vacuum. But, they are free to completely block off any venting going the other way (In other words, should hold up to 10 - 14 PSI pressure.)

[Matt]

so it will allow draw from the tank and not allow any spillage in the event fuel was to flow back through itself and out potentially causes a fire?? so one way only, from vent to tank but not vice versa?? thanks

[bobodu]

Suck yes....blow no.

[StarTech]

The method used by these valves is the same the check valves in our veins in the lower part of our body. Fluids and air can only flow one way.

[Matt]

thanks fellas!! matt.

[bobodu]

The method used by these valves is the same the check valves in our veins in the lower part of our body. Fluids and air can only flow one way.

There is another check valve that is designed to only work one way....used to anyway. I don't think I like all this change...