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 causes self-siphonage in a plumbing trap?
Answer: The momentum of water leaving the fixture creates a vacuum that pulls the trap seal out
Self-siphonage occurs when the slug of water leaving the fixture creates negative pressure behind it in the trap arm, pulling the trap seal water out through siphonic action. Proper venting prevents this by admitting air behind the water slug.
What is 'induced siphonage' in a drainage system?
Answer: Trap seal loss caused by the discharge of another fixture on the same branch
Induced siphonage occurs when a nearby fixture discharges and creates negative pressure in the shared branch drain, pulling the trap seal from an adjacent, non-discharging fixture. Proper branch venting prevents this.
What is the fixture unit rating for a shower stall in a residential building?
Answer: 2 fixture units
A residential shower stall is rated at 2 fixture units, reflecting its drainage flow rate and load on the drainage and venting system.
What is the minimum pipe size for a building storm drain?
Answer: 4 inch
The minimum building storm drain size is 4 inches to handle the volume of rainwater collected from roof areas, ensuring adequate capacity during heavy rainfall.
What determines the size of a roof drain leader (rain water leader)?
Answer: The area of roof being drained and the local rainfall intensity
Roof drain leaders are sized based on the horizontal roof area being drained and the local rainfall intensity (typically in mm/hour for a 5-minute duration, 10-year return period), ensuring the pipe can handle peak storm flows.
Why should storm drainage never be connected to the sanitary sewer system?
Answer: Rainwater would dilute the sewage treatment process and surcharge the sanitary system during storms
Connecting storm drains to the sanitary sewer causes massive surcharging during rain events, leading to sewage backups into buildings and raw sewage overflows into waterways. It also dilutes sewage, reducing treatment efficiency.