Such a simple plumbing item to do but so often done incorrectly... enter the fixture trap.
Plumbing fixture traps are devices that keeps a small amount of liquid every time the fixtures is used in it to create a trap seal.
The amount of retained liquid is called a trap seal. Without a trap to seal off plumbing fixtures, unwanted and nasty things such as methane gas and vermin can creep into the house.
In addition to a trap seal you want the trap to be self scouring or better stated self cleaning.
These need to be properly installed to function properly. Under normal conditions, traps are required to have a seal depth between 2 inches up to 4 inches. As the seal depth increases, so does the pressure required to push the fluid through the trap. If the pressure is too great, the water from a fixture may not be enough to cause the water to flow quickly through the trap and sediment can begin to accumulate at the bottom of the trap. And if the trap is not installed correctly then the mechinism for scouring will be impared.
From 2015 UPC
1002.2 Fixture Traps.
Each fixture trap shall have a protecting vent so located that the developed length of the trap arm from the trap weir to the inner edge of the vent shall be within the distance given in fable 1002.2, but in no case less than two times the diameter of the trap arm.
1003.1 general requirements.
Each trap, except for traps within an interceptor or similar device shall be self cleaning. Traps for bathtubs, showers, lavatories, sinks, laundry tubs, floor drains, urinals, drinking fountains, dental units, and similar fixtures shall be of standard design, weight and shall be of ABS, cast-brass, cast-iron, lead, PP, PVC, or other approved material. An exposed and readily accessible drawn-brass tubing trap, not less than 17 B & S Gauge (0.045 inch) (0.114 mm), shall be permitted to be used on fixtures discharging domestic sewage.
1005.0 Trap Seals.
Each fixture trap shall have a liquid seals of not less than 2 inches (51mm) and not more than 4 inches (102mm), except where a deeper seal is found necessary by the Authority Having Jurisdiction. Traps shall be set true with respect to their liquid seals and where necessary they shall be protected from freezing.
Oten these type of installation are fairly easy to correct but should always be done by a qualified person or profesional.
"Quality means doing it right when no one is looking."
If you find any errors or have additional information that would expand on any code, building standards or manufacturer requirements please let me know.
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