Drainage and Venting Systems Flashcards
6 cards from real 306A practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Drainage and Venting Systems flashcards as text
What is the primary purpose of a vent system in a drainage installation?
Answer: To equalize air pressure in the drainage system and protect trap seals
The vent system equalizes air pressure within the drainage piping, preventing siphonage and back-pressure that would otherwise break trap seals and allow sewer gases to enter the building.
What is the minimum slope required for a 2-inch horizontal drainage pipe?
Answer: 1 in 25
A 2-inch horizontal drain requires a minimum slope of 1 in 25 (approximately 4%) because the smaller pipe diameter needs a steeper grade to achieve self-cleansing velocity.
What is the maximum number of fixture units permitted on a 2-inch vertical waste stack?
Answer: 16
A 2-inch vertical waste stack can handle up to 16 fixture units because vertical flow uses only a portion of the pipe cross-section, with the centre remaining open for air flow.
What is a 'stack vent' in plumbing terminology?
Answer: The extension of a soil or waste stack above the highest horizontal branch connection
A stack vent is the extension of a soil or waste stack above the highest horizontal drain branch connection. It continues upward through the roof to serve as a vent for the stack.
What fitting is required when connecting a horizontal branch to a vertical soil stack?
Answer: Sanitary tee or wye fitting
A sanitary tee or wye fitting is required to ensure proper flow direction when connecting a horizontal branch to a vertical stack, preventing turbulence and blockage.
What is the minimum diameter of a vent serving a 3-inch trap?
Answer: 1½ inch
The vent serving a 3-inch trap must be at least 1½ inch in diameter according to the vent sizing tables, which specify the minimum vent size based on the trap size and developed length.