1002.4 Trap seals. Each fixture trap shall have a liquid seal of not less than 2 inches (51 mm) and not more than 4 inches (102 mm), or deeper for special designs relating to accessible fixtures.
❖ Protection of the trap seal means that during the normal operation of the plumbing system, the water seal remains in the trap. Each trap has a minimum trap seal depth of 2 inches (51 mm) translating to a hydro-static pressure equal to a 2-inch w.c. (498 Pa).
The depth of seal in the water trap needs to be a minimum of 75mm to comply with new build regulations where waste water discharges into a single stack waste system. Below are the common types of trap which are used on installations of sinks, basins and urinals.
Water seal trap:
In practice, the depth of the water seal varies from 25 to 75 mm, with 50 mm being quite common. Traps are the fittings placed at the ends of the Soil pipes as well as waste pipes to prevent the entry of foul gases from the drains into the interior of the houses or buildings.
Dimensions of a P-Trap
Another important dimension is the 'trap seal depth' - the height of the water seal inside the trap. This is typically between 2 and 4 inches, and is crucial in preventing sewer gases from entering the building.
When the trap is too deep, liquid may flow through it too fast, which can lead to siphoning of the trap seal and sludge buildup. The drain connection at the wall is too high on this sink, resulting in a 9-inch-deep trap seal — 5 inches deeper than is allowed by code.
There is no standard for the depth of a shower drain P-trap, as it is only based on the size of pipes or fittings used. It would help if you didn't worry about its depth as long as it is securely covered and functioning properly.
Each fixture trap shall have a liquid seal of not less than 2 inches (51 mm) and not more than 4 inch- es (102 mm), 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.
Measure and record the trap seal depth by measuring the height from the invert of the trappage back plate to the surface of the water.
Preventing evaporation and intruders
Evaporation is a natural occurrence, especially in unoccupied homes like vacation residences. The prescribed minimum depth serves as a guideline to prevent complete evaporation, a crucial consideration for houses left empty for extended periods.
The trap depth is the minimum energy that is required to free a charge from the trap. It is chosen to be large enough so that the rate of detrapping is very low at room temperature.
In the majority of PE pipe applications, a minimum of 75 mm of bedding material is used in both trenches and embankments in soil excavations. For excavations in rock, 150 mm bedding depth may be required.
Each “P” trap shall have a water seal of not less than 2 inches and not more than 4 inches and shall be set true to its seal. (6) Size. Traps shall be not less than 1 1/4 inches in diameter. A trap shall not be larger than the waste pipe to which it is connected.
Descriptions Standard Requirements Depth of Water Seal Min 50mm Passage Clearance Min 25mm Outlet Diameter Min 75mm Floor Trap (Water Compartment) Shall be integral type, removable trap is not allowed.
The seal dimensions refer to the approximate depth of water trapped in the bend. Meets current regulations which specify that where waste pipes discharge into a single stack (as is the current 'new build' requirement), the depth of water seal must be at least 75mm (3 inches).
A liquid seal of not less than two inches and not more than four inches was found to be the optimum depth to provide the necessary protection against sewer gas and still provide the self-scouring effect needed to keep the trap from fouling (see Figure 1005.1).
After each test a minimum of 25 mm of water seal should be retained in every trap. Each test should be repeated at least three times, the trap or traps being recharged before each test.
Plumbing Trap
Plumbing traps today is an essential part of any drainage system. Based on the requirement of the Indian building code all plumbing traps must incorporate a 50mm minimum depth for the water seal.
It has remained an essential feature of all building drainage design since the early 19th century. The depth of the water seal, 50 or 75 mm, is sufficient if properly retained to prevent any passage of air into habitable space from the drainage network.
The bend in the p-trap collects water in the curve, creating a 1-½-inch to 2-inch water seal at the weir, preventing sewer gasses and odor from entering the home. The weir is the upper bend of the p-trap in which the water would start to spill into the wall tube.
tl;dr The seal is the rock layer above that will not allow passage of the hydrocarbons from below. The trap is the configuration of the reservoir, the seal and other geologic features that prevent the hydrocarbons from migrating around the seal.
According to building regulations, the minimum depth of a water seal in a shower trap is 50mm. However, you'll find some shower traps have a 19mm water seal which are designed to replace traps where older, shallow traps were installed before the regulations were updated.
Each fixture trap shall have a liquid seal of not less than 2 inches (51 mm) and not more than 4 inches (102 mm), or deeper for special designs relating to accessible fixtures. Trap seals of emergency floor drain traps and trap seals subject to evaporation shall be protected by one of the methods in Sections 1002.4.
No fixture shall be double trapped. Exceptions to the separate trapping requirements are as follows: (1) Fixtures having integral traps. (2) A combination plumbing fixture may be installed on one trap provided one compartment is not more than 6 in.