7. and 8. Sanitary Drainage, Vent and Stormwater Drainage Flashcards
Define a Horizontal Pipe?
Any pipe at a lesser than 45 degree angle.
Define a Vertical Pipe?
Any pipe at a 45 or greater degree angle.
What is a Drainage Fixture Unit?
dfu, measure of probable discharge of wastewater and waterborne waste into a drainage system. Used to estimate drain and vent pipe sizing.
What is a Positive System?
Drains and or vents too small, won’t flush.
What is a Negative System?
Drains and or vents too large, suck trap water out.
What is the typical drain to vent sizing?
4 inches to 2 inches.
How full do horizontal drain pipes need to be for proper drainage?
1/3.
What is the typical max for commercial vent piping?
4 inches.
What happens to pipe sizing when there are many turns in a pipe?
Pipe size must increase. This is why 45 degrees are used instead of 90.
What is an Offset Stack and it’s purpose?
Combination of bends or elbows that connects two stack pipes that aren’t aligned. Can be used to balance pressure in drain system to reduce waste speed and prevent trap siphonage.
What is a main method of Vent Piping in commercial buildings to prevent trap siphonage?
Vent drain pipes every few floors instead of every floor. Slows air to pillow waste fall.
What is a Common Vent and its use?
Connects 2 fixture drains, vents both, must be above height of fixture. Back to back toilets.
What is a Wet Vent?
Portion of vent pipe through which liquid waste flows. Common in residential between 2 fixtures or can pick up lavatory and sink below, etc. Mostly for tubs and sinks, not constant use. Saves money.
What value do Individual Vents have?
Guarantee no loss of trap seal. Can be used in condos where two lavatories share same vent. Individual Vents prevent Cross Siphonage.
What is a Vented Closet Tee?
Combines waste inlets with a vent. Saves space, time, money.
