Drainage, Waste, and Vent System

Drainage, Waste, and Vent System

• This system sometimes is called the Sanitary Drainage and Vent System
• It involves a network of pipes removing wastewater from buildings

Sanitary Drainage

• Sanitary Drainage features traps at each fixture
• Fixture branches, stacks, and drain pipes transport wastewater to plumbing fixtures of a building

Vent System

• The vent system introduces and circulates air
• This helps maintain atmospheric pressure in the drain lines
• Adequate gravity flow for wastewater relies on maintaining atmospheric pressure
• Venting exhausts sewer gases outdoors
• Venting prevents systems from having negative pressure
• Preventing negative pressure stops sucking water from fixture traps

Traps

• Traps involve U-shaped pipes
• These pipes capture and hold a small amount of wastewater as it is poured down a fixture drain

Trap Seal Loss

• Loss of water seal in a trap will let objectionable sewer gases to go into the building
• Trap Seal Loss can occur due to:
  • Backpressure
  • Capillary action
  • Evaporation
  • Direct or self-siphonage
  • Indirect or momentum siphonage
  • Wavering or wind effect

Backpressure

• Backpressure is caused by positive pressure
• This happens when a large amount of water discharges into a stack from upper floors, creating pressure at the base
• Without adequate ventilation, this pressure may remove a trap seal

Capillary Action

• Capillary action is the wicking away of a water seal
• Foreign objects like hair, thread, cloth, or fibers lodged into the trap and extending towards the outlet can cause this

Evaporation

• Evaporation occurs in traps connected to infrequently used fixtures at high temperatures
• The water in the seal evaporates

Direct or Self-Siphonage

• Direct or Self-Siphonage are caused by negative pressure
• Occurs in unventilated traps serving oval-bottom fixtures, like lavatories or slop sinks
• Created by a rapid flow of water through the pipe

Indirect or Momentum Siphonage

• Indirect or Momentum Siphonage is caused by negative pressure
• Happens when water discharged from one fixture pulls the trap seal of another fixture on the same discharge line

Wavering or Wind Effect

• Wavering or Wind Effect is caused by high-velocity fluctuating wind across the top of the stack vent
• This creates a wave motion in the trap, causing water to wash over the weir

Interceptors

• Interceptors are passive devices in plumbing systems
• They trap, separate, and retain toxic or undesirable wastewater substances before discharge to sewer lines
• Interceptors are also called Clarifiers

Grease Trap or Interceptor

• Grease traps receive wastewater from sinks, dishwashers, and floor drains
• They can be found in restaurants, cafeterias, and commercial food establishments before being drained to the sewer system

Oil-Sand Interceptor

• These separate and remove floatable (oils) and settleable (sand/metals) materials from wastewater before sewer discharge
• This type of interceptor is used in manufacturing plants, vehicle service facilities, and car washes

Fixture Drain

• The drainpipe runs from the trap of a fixture to the junction with another drainpipe

Fixture Branch

• This drainpipe connects two or more fixture drains to a main drain or stack

Stack

• The general term for any vertical line of soil, waste, or vent piping
• A vertical pipe that fixture branches feed into

Soil Stack

• Soil Stacks carry wastewater from water closets or similar fixtures
• Includes human wastes

Waste Stack

• These carry all wastes except human wastes

Building Drain

• A building drain is part of the lowest horizontal piping of a drainage system
• Receives discharge from soil, waste, and drainage pipes within the building walls
• It conveys it to the building sewer starting 0.60 m outside the building wall

Building Sewer

• A building sewer is horizontal piping for drainage
• It receives discharge that begins from the end of the building drain
• Conveys the discharge to a public, private, or individual sewage disposal system or disposal point

Sanitary Sewer Main

• The sanitary sewer main is the pipe which wastewater flows through
• It conveys wastewater from a building to a wastewater treatment plant

Cleanouts

• This is a plug or cover joined to an opening in a pipe
• This part removed to allow access for pipe inspection or cleaning

Vent Pipe

• This pipe ensures circulation of air in the plumbing system while relieving negative pressure on trap seals

Vent stack

• A vent stack is a vertical vent pipe for air circulation to and from any drainage system part

Stack Vent

• A stack vent is the extension of a soil or waste stack above the highest horizontal drain connected to the stack
• Stack Vent Through Roof is the uppermost end of the stack vent above the roof

Individual Vent

• A individual vent installed to vent a fixture trap
• It connects to the vent system above the fixture or terminates in the open air
• Can be called Revent Pipe or Backvent Pipe

Continuous Vent

• This is a vertical vent that is a continuation of the drain it connects to

Common Vent

• A common vent is a single vent at the junction of two fixture drains
• It serves as a vent for two traps

Circuit Vent

• This vent group starts in front of the extreme fixture connection on a horizontal branch
• It connects to the vent stack

Loop Vent

• This vertical vent connects on a horizontal soil or waste pipe branch
• It's downstream of the last fixture connection, turning toward the highest overflow level of the highest fixture
• The end is then connected to the stack vent

Wet Vent

• Wet vents have a portion of the vent pipe where wastewater flows

Dry Vent

• Dry vents don't carry liquid or water-borne wastes

Local Vent

• This pipe or shaft conveys foul air from a plumbing fixture or room to the outer air

Relief Vent

• Relief vents are vertical vent lines that help circulate air better between the drainage and vent systems
• It can be an auxiliary vent on specially designed systems

Yoke Vent

• This connects upward from a soil or waste stack below the floor and horizontal connection to an adjacent vent stack
• This is above the floor and higher than the highest spill level of fixtures
• It works to prevent pressure changes in the stacks