For the proper and effective functioning of the sewerage system in your house, sewer appurtenances are necessary. These include manholes, lamp holes, various types of plumbing traps, intercepting chambers, flushing tanks, ventilating shafts, street inlets, siphons, venture flumes, leaping wires, etc.
Plumbing Traps are an important component of a drainage system. They prevent the ingress of foul air, insects, and vermin from the sewers into the building and resist the spread of disease. Traps retain a body of water, which acts as a water seal.
Plumbing traps should be of the self-cleaning type. They should generate enough velocity from the available flow to have a self-cleansing effect, a smooth finish, and a full uniform bore.
Some manufactured plumbing fixtures, e.g. water closets, bedpan washers, and certain models of urinals, have integral traps built within the body of the fixture.
Different Types of Plumbing Traps
Following is the list of different types of plumbing traps.
- Floor Trap or Nahni Trap: To know more, discover Floor Trap or Nahni Trap
- Gully Trap: To know more, read Gully traps.
- P, Q and S-Trap
- Intercepting Trap: To know more, refer to Intercepting Trap
- Grease Trap
Plumbing traps are fittings at the end of soil or waste pipes that stop foul gases (smell) from coming out of the soil pipe or waste pipe.
Plumbing Trap is part of the drainage (sanitary) system designed to retain a small quantity of wastewater from the discharge of the fitting to which it is attached as a barrier to prevent foul gases or air from entering the building.
Also Read: Residential Plumbing System
Ideal Requirements of Plumbing Traps
The requirements of an ideal plumbing trap are:
- The plumbing trap must work without mechanical help and be able to pass wastewater freely.
- Whether sewage is flowing or not, the trap must be able to prevent foul gases (bad smells) in either direction.
- Traps must be self-cleaning.
- Traps must have a water seal, preferably not less than 50 mm deep.
- Traps must be strong and leak-proof.
- Traps should be made available with a clean-out or other means of access to the interior in the event of chock. The cover must be gas-tight and water-tight.
- Traps must have no internal projections to catch and hold hair, lint, bits of matches, etc, but must have a smooth inner surface, every part of which is automatically scoured by the flow of the sewage or sewer air leakage.
- Where necessary it must be back – vented.
- Traps must not have concealed partitions, tubes, or other invisible parts, as construction defects might permit sewer air to enter the house.
Normally, the trap seal varies from 25 to 75 mm deep.
Water Seal in Traps
A trap is a plumbing fitting, or a part of a sanitary appliance, designed to hold a quantity of water. This water is called the water seal, which acts as a barrier to prevent air from passing out of the waste pipe into the room. Therefore, soil and waste pipes are installed carefully, and the water seal is not destroyed under any condition.
Water closets, and in some cases, urinals, have integral traps. All other fixtures have external traps with adequate water seals. The diameter of the trap shall, in no case, be smaller than the diameter of the outlet of the fixture to which it is connected. Traps shall be of a self-cleaning design with a uniform bore and shall not be dependent on internal partitions or other movable parts for retention of the water seal. Do not connect one trap to another trap. The diameter of the outlet pipe from a floor trap shall not be less than the size of the trap outlet.
Loss of water seal in traps is observed due to the following reasons:
- Evaporation
- Capillary action
- Momentum
- Leakage
- Wavering out
- Compression or back pressure
- Induced siphonage
- Self-siphonage
Do not make plumbing traps or drainage connections inside cold storage, walk-in freezers, or stores for food and medicines, as there is a danger of water freezing in the trap and damaging it. Take all precautions to prevent any contamination hazards when handling installations.
Also Read:
What is Septic Tank and Soak Pit
Things to Check on During Plumbing Inspection