VENTS AND VENTING
Venting Systems • Definition Venting Systems - means an assembly of pipes and fittings that connects a drainage system with open air for circulation of air and the protection of trap seals in the drainage system. • Purpose To maintain atmospheric pressure by supplying a free flow of air, preventing the creation of a siphon in the drainage system.
• Important factors for designing a venting system are the amount of fixture units the vent or branch vent is serving and its developed length. HYDRAULIC GRADIENT – A line drawn from the center of the water level to the point where it falls vertically by gravity. This will show how a vent can possibly fill with water when the fixture discharges fully into the drainage system.
VENTING SYSTEM – The stack elevation shows several forms of individual venting and group venting.
TYPES OF VENTS • Main soil and waste vent • Main vent • Individual vent or back vent • Unit vent • Circuit vent or loop vent • Relief vent • Yoke vent • Wet vent • Looped vent • Utility vent
Main vent • The principal portion of the vent pipe system to which vent branches may be connected. • It serves as a collecting vent line.
Main soil and waste vent - The backbone of the entire sanitary system - Continues to the roof, that portion penetrating the roof is Vent Stack Through Roof (VSTR) • The portion of soil stack pipe above the highest installed fixture branch extending through the roof.
• Back Vent or Individual Vent - means a pipe that is installed to vent a trap off the horizontal section of a fixture drain or the vertical leg of a water closet or other fixture that has an integral siphonic flushing action and “back vented” has a corresponding meaning.
• Unit, common or dual vent - an arrangement of venting so installed that one vent pipe will serve two (2) traps
Wet Venting • Wet vent means a waste pipe that also serves as a vent pipe. • Wet venting is a form of group venting based on the simple principle that waste water clings to the side of a vertical waste pipe leaving the center core of the pipe open. This means a pipe, properly sized can have open center of a wet vent serve as a vent for fixtures downstream. • Continuous vent means a vent pipe that is an extension of a vertical section of a branch or fixture drain.
WET VENTING – A bathtub being wet vented by a basin with the connection to the horizontal fixture drain within two fixture drain diameters using a WYE fitting. A shower wet vented by a basin to a vertical fixture drain using a sanitary tee fitting.
Circuit Venting • Circuit Venting is a form of group venting sometimes confused with Wet Venting. This is because a Circuit Vent looks like a Wet Vent.
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- Fall '19