How Does It Work

dayspring

Just pondering this in my mind and it won't go away. Maybe on of the plumbers here can answer this:

How does the vent pipe work? Does it let air out or let air into the drain lines or does it do both?

Can't settle this one in my mind. Thanks

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Dustball

Easiest way to have you picture it is comparing it to a gas can you use you fill your lawn mower with. With the vent cap closed and when you pour, the gas comes out slowly and inconsistently. You're creating a vacuum in the container when you're pouring. Open the vent cap and you have a place for air to come in and fill that vacuum and equalize the pressure inside the can to the atmosphere and your flow improves dramatically.

threaderman

On the user side of each fixture you have air,normal atmospheric pressure.Once a fixture is used it draws in air but stays at normal atmospheric pressure .The waste/water running through the drain of course displaces and pushes the air.If the air cannot be expelled quickly enough it causes a pressure increase on the downstream side while causing a negative pressure on the upstream side and the upstream side will pull air from traps in order to equalize.The vents allow air movement in the system to maintain equal or atmospheric pressure.Venting also serves as the escape point for noxious as well as flamable gases.Hope that helps.Their are many types of venting systems ,but the key is keeping air equal in the system.

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dayspring

Thanks, Threader

So, what you are saying, if I read it correctly is:

Air moves both directions, depending on the need of the system at the particular time.

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threaderman

Absolutely

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Joe ---International Code Council Member

Your plumbing & gas specialist proudly serving Oklahoma City OK, Moore, Warr-acres, Norman, Midwest City, Edmond, Bethany, Forest Park

dayspring

OK, I gots it! Thanks guys!

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