9. and 10. Plumbing Traps and Sizing Pipes Flashcards
What is the purpose of a Trap and what feature must they all possess?
Holds a water seal to prevent gas from entering the domicile. All must have a clean out or be easily removeable.
What trap material is used for residential and commericial?
PVC for residential. Chrome plated metal for commercial.
What is the default trap size for most uses?
1.5 inch.
What is the difference between Common Seal and Deep Seal Traps?
From Crown to Top of Dip: Common are 2 to 4 inches, Deep Seal are minimum of 4 inches.
What are Antisiphon Traps?
Globe or Drum Traps, which possess a water volume of water for sealing. Used in old bungalows or scientific chemical drains. Hard to rod.
What is Self-Siphonage?
Unequal pressure between drainage system and atmosphere caused by rapid flow of waste water through trap. Like draining double bowl sink at same time, floods other sink.
What are the max distances the fixture trap to vent can be?
1.25 inch is 2 feet 6 inches. 1.5 inch is 3 ft 6 in. 2 in is 5 ft. 3 in. is 6 ft. 4 in. Is 10 ft.
What is Back Pressure and where does it occur?
Backflow caused by downstream pressure in water distribution pipe being higher than the water supply pressure. Think toilet or sink, caused by clogging, turbulence at base of stack or where soil stack changes direction - turbulence and bubbles.
What is an Auto-Trap Primer and its purpose?
Mechanism that feeds water into floor drains to prevent trap evaporation.
What is a Water-Saver Trap Primer?
Water line attached to a drain that uses drain water to fill floor traps.
What happens to water pressure when pipe sizes change?
Bigger the pipe, more volume but less pressure.
How are distribution pipes run concerning pipe size?
Always large to small to maintain equal and stable pressure. End pipe always 1/2in.
What is the minimum flow rate feeding a toilet?
1.6 gpm.
What factors must be considered when sizing pipe?
Based on total number of fixture values, account for friction - metal worse than plastics - number of pipe bends, length of pipes.
WSFU?
Water Supply Fixture Unit. Measure of estimated water demand of a plumbing fixture.
