A plumbing trap is a device found in the drain-waste-vent system that prevents sewer gases from entering buildings, homes and apartment blocks.
A plumbing trap prevents sewer gases from entering any kind of structure by creating an airtight trap seal through water sealing or small vent openings. Drain traps, bottle traps and drum traps are usually either bendable tubing or hardened plastic, although some plumbing codes will permit other materials to be used as well.
In the drain-waste-vent system, a plumbing trap or trap operation is installed on every fixture that cannot be directly connected to a waste materials stack.
A plumbing trap primer is an angled fitting that provides self-cleaning at joints of a horizontal vent pipe, usually around 45 degrees from vertical. This combined with an intercepting trap and lets you easily remove objects from a multitude of traps such as a drum trap, grease trap, floor trap, bottle trap, gully trap without having to remove them from further down inside the drain pipes downstream or perform more extensive excavation near fixtures that might otherwise be necessary.Traps are mandatory in some countries due to sanitation reasons; there they are known as full "S" traps.
A running trap primer is an angled fitting that provides cleanouts at joints of horizontal drainage piping, usually around 45 degrees from vertical. This lets you easily remove objects from traps without having to remove them from further down inside the pipe or perform more extensive excavation near fixtures that might otherwise be necessary.
All traps work in a very simple and basic way: they hold water, and since water is not compressible, it acts as a barrier between the sewer gas and your home or building's interior air. Make sure you are regularly checking and fixing water closets. A certain amount of venting via small openings is acceptable with most plumbing codes; however, your location will help determine how much venting actually occurs.
The most common types of traps are "P'' traps and "S" traps.
The most familiar of the two traps is the P trap. It's the curved piece of drain tubing found under bathroom and kitchen sinks, as well as under lavatories in smaller bathrooms. It is shaped like the letter "P" and is often made of metal, plastic or glass. The traps don't actually trap anything themselves, they're simply a U-shaped pipe that bends in a way that discourages odours from escaping into the room. As water drains out of a sink or lavatory, it flows down through the drain opening and past an S-shaped section of P traps tubing before flowing onto the main drainage system in the building P traps help in allowing waste materials from a plumbing fixture to flow freely on its way toward the sewer while retaining enough water at all times to maintain a water seal. In other words, there must be some free space filled with air above whatever you put in your drain so it doesn't get siphoned out. A P trap provides a safety mechanism to protect buildings from sewer gas, which are produced by decaying organic matter and can be quite noxious.
The other is S trap, which looks like a lowercase letter "S" lying on its side. It's found under a bathroom sink or kitchen sink and is usually called a sink trap. The S trap of the sink drain doesn't actually stop sewer gas odor from entering the room; instead, it prevents vermin and sewer gas from flowing up into your home. This is because sink drains and shower drains to the sewer at a lower level than water in the trap, and the curve of the pipe holds some wastewater inside.
Typically, a trap is installed near the plumbing fixture it serves. If you have a sink on one side of your bathroom and a toilet on the other, you'll have a P trap for each. In some cases, there might be multiple plumbing traps connecting several different plumbing fixtures to the same floor drain pipe on the ground floor.
For example, you might have a p trap for both your sink and shower or multiple S traps or a single large diameter S trap to serve the waste outlet and collect debris from several sinks and toilets. Same goes for the laundry sinks attached to your washing machine and possibly dishwasher.Most types of plumbing traps can be made from either plastic or metal. Plastic is often used in homes where the water supply is particularly corrosive (as in areas with very hard water) since it's unlikely to damage the PVC over time. If your fixture was manufactured before the 1980s your trap will probably be made of metal; otherwise, you might have a plastic model. However, fixtures and traps aren't limited to these materials alone - they can be made from glass or ceramic as well.
If these foul gases reached living areas, then you'd suffer from the unpleasant odour of sewer gasses not to mention the potentially serious health risk associated with prolonged exposure to such foul gases.
Without traps, every time you run water down a sink or flush a toilet, those harmful fumes would escape into your home.A Y-shaped trap is used in situations where a sink and lavatory share the same drain. The Y shape allows each fixture to have its own P trap while still connecting them to the same plumbing system. In some cases, there may also be an S shaped trap section of pipe between the two traps, which caters for overflow from both devices.
Some sinks and lavatories require more than one type of trap: one for water and another for the waste pipe. These are known as combination traps or double traps and they're usually made of multiple components rather than just a single piece of tubing like standard types. For example, a sink might have an external house trap made of metal or plastic with rubber fittings to prevent leaks. There will also be an internal trap formed from ceramic discs that are held in place with special clips called 'doughnuts'. When wastewater or building sewer goes down your drain body, it enters the bottom of this building trap before heading through the vertical pipe leading to the sewer system. The curve catches some water so there is always at least a small amount in here, preventing odours of foul gasses and foul air from rising up into your bathroom or kitchen.
The doughnut-shaped gasket that fits into the upper part of a combination/double trap is known as a 'plumbing doughnut' or simply 'doughnut'. This interceptor manhole is designed to prevent sewer gases from making their way back up the pipe towards your home. As always, make sure you use appropriate plumbing tools and parts for your fixture (e.g., plastic for plastic) and it will be difficult to go wrong whether it a trap outlet, q trap, low-level bath trap, bell trap or straight through trap.