Aditi K. ShahRol l No. : 45

Traps

A trap is a depressed or bent sanitary

fitting which always remains full of water

(water seal). The function of a trap is to

prevent the entry of bad smelling gases into

the house. The effectiveness depends upon

the depth of water seal, which varies from

25 to 75mm

Requirements of good trap:

1. It should be capable of being easily cleaned.

2. It should be easily fixed with the drain.

3. It should be of simple construction.

4. It should possess self-cleansing property.

5. It should posses adequate water seal to fulfil the purpose of installation.

6. It should be free from any inside projection which are likely to obstruct the passage of flow of sewage.

7. The internal and external surfaces should be of smooth finish.

Types Of Traps:

a. P-trap.

b. Q-trap.

c. S-trap.

P- trap:

• As its name suggests, the p-trap vaguely

resembles the letter "p" when turned on its

side.

• P-traps exit into the

wall

behind the sink

S- trap:

• The "S" shape traps water so that odours

from the sewer don't come up through the

drain. A second and only slight benefit from

the shape is that it can trap heavier objects,

such as rings, that fall into the drain.

Q- trap:

• This trap is used in toilet under water

closet. It is almost similar to S trap and is

used in upper storey other than ground

floor.

Vent pipe:

• The pipe installed for the purpose of

ventilation is known as vent pipe through

which foul gases escape into atmosphere.

• Without a vent pipe (stack vent), as

wastewater flows down your waste pipe, a

partial vacuum would develop at the top of

the pipe which would stop the wastewater

from flowing the rest of the way down.

Vent pipe (fig.):

Rainwater pipe:

• The pipe carrying only rainwater (from the

roof tops) is called rain water pipe.

• The advantage of rainwater pipes is:

1)Prevents accumulation of water

on roof.

2)Water can be collected for

harvesting, domestic purposes

like washing, cleaning etc.

Rainwater pipe (fig.):

Anti- siphonage pipe:

• Anti- siphonage pipe means any pipe

provided in conjunction with a trap in the

sanitary fitting to prevent unsealing of the

trap by siphonage or back pressure.

• Back- siphonage causes breaking of the

water seal therefore anti-siphonage pipe is

requires

Anti- siphonage pipe (fig.):