TRAPS

• Traps are defined as fittings at the end of soil pipes of waste pipes to prevent foul gases coming out of the soil pipe/ waste pipe

TRAPS

Traps are an integral part of a modern sanitary system, being designed to retain a small quantity of the waste water from the discharge of fitting to which they are attached as a barrier to prevent foul air entering the building as shown in Figure

Traps should be self-cleaning, that is to say , they should be designed so that their walls are scoured by the discharging water. One of the advantages of modern traps constructed of plastic materials is the ease with which they may be dismantled for cleaning.

Traps And Pipes and other components of house Drainage System

Traps And Pipes and other components of house Drainage System

• Following are the main components of House drainage system.

• Traps: Good Traps should have following Qualities:• Should provide enough water seal ( around 50 mm)

with large surface area.• Interiors surface should be smooth so that the flow is

not obstructed which enables self cleansing.• An assess door should be provided for cleaning the

trap.• It should be made of non- adsorbent material.

• Following are the main components of House drainage system.

• Traps: Good Traps should have following Qualities:• Should provide enough water seal ( around 50 mm)

with large surface area.• Interiors surface should be smooth so that the flow is

not obstructed which enables self cleansing.• An assess door should be provided for cleaning the

trap.• It should be made of non- adsorbent material.

Classification of TrapsClassification of Traps

• Depending upon the shapes the traps are classified as:

• P-Trap• Q-Trap• S-Trap• Above three types of traps are shown in the

following figures.• The depth of a Trap Seal would depend upon the

usage of a pipe. The trap seal varies from 25 to 75 mm deep.

• Depending upon the shapes the traps are classified as:

• P-Trap• Q-Trap• S-Trap• Above three types of traps are shown in the

following figures.• The depth of a Trap Seal would depend upon the

usage of a pipe. The trap seal varies from 25 to 75 mm deep.

P, Q and S TrapsP, Q and S Traps

Q TrapQ Trap S Trap S TrapP TrapP Trap

P, Q and S TrapsP, Q and S Traps

Nahni TrapNahni Trap

Gully TrapGully Trap

Intercepting Traps

Advantage of Intercepting TrapsAdvantage of Intercepting Traps

• Foul Gases of larger municipal sewers are prevented from entering house drainage system.

• Harmful pathogens are not entered in house drains.

• Well designed and contructed interceptors can quickly remove foul matter of house drain to muncipal sewers.

• Foul Gases of larger municipal sewers are prevented from entering house drainage system.

• Harmful pathogens are not entered in house drains.

• Well designed and contructed interceptors can quickly remove foul matter of house drain to muncipal sewers.

Loss of Trap Seals If a trap seal loss, smells from the sanitary appliances would enter the building. Therefore the water seal in the trap must be maintained under all circumstances.

1) Evaporation

When trap is not being used, the rate of water evaporation depends upon the relative humidity of the air in the room. The rate is approximately 2.55 mm per week, so a 25 mm seal would last for 10 week. See Figure 3.6.

Figure 3.6 : Evaporation occur when trap not being used

2) Capillary attractionIs another rare occurrence which happens in ‘S’ trap when a piece of porous material being caught over the bend of a trap absorbs water and deposits it down the waste discharge pipe. See Figure 3.7.

Figure 3.7 : Capillary attraction

3) MomentumThis is caused by a sudden discharge of water from a bucket. Due to velocity water is discharged and it shoots around the trap bend and goes down the waste pipe, leaving no seal.

4) Leakage It is caused by a fault in the trap or plumbing installation and water on the floor would be apparent.

5) Wavering out This is caused by the effect of the wind which passes over the top of the ventilation pipe and thus causes pressure fluctuations. See Figure 3.8.

Figure 3.8 : Wavering out

6) Compression or back pressure This occurs in high rise buildings. When water is discharged down to the main discharge stack, air is compressed at the base of the stack. A waste pipe connected to the stack in the pressure zone may have the seal of the trap lost by the compressed air forcing out the water. Detergent foam increases the risk of compression. See Figure 3.9 .

7) Induced siphonageThis is caused by discharge of water from another sanitary appliance connected to the same discharge pipe. In either a vertical or horizontal main waste pipe, as water flows down the pipe and passes the branch pipe connected to it, it draws air from it, thus creating a partial vacuum and subsequently siphonage of the trap takes place. See Figure 3.10.

8) Self siphonage This is caused by appliances such as wash basins and other small appliances, due to their curved shape, and is caused by a moving plug of water in the waste pipe. A partial vacuum is created at the outlet of the trap, thus causing siphonage action takes place. See Figure 3.11.

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