Traps
The devices which are
used to stop the escape of foul gases inside or outside the houses are known as
traps. The foul gases produced inside the sewers, drains may cause nuisance by
entering in houses through house connecting pipes if their passage is not checked.
The trap generally consists of a bend tube which provides a water seal between
the atmosphere and the sewer gas. The efficiency of the traps depends on the
depth of water seal, deeper the seal more efficient will be the trap.
The essential qualities of a good trap are
1) It
should be simple in construction.
2) It
should be of non-absorbent material.
3) It
should be provide sufficient depth of water seal.
4) It
should be self cleansing.
5) It
should have smooth internal and external surface.
6) It
should not obstruct the sewage flow.
7) It
should have provision for means of access.
The water seal of the trap can break due to
following reasons the remedies are given in the brackets.
1) Siphonage
and air compression : ( providing adequate means of trap ventilation)
2) Momentum
: (provision of anti – D trap to retard the velocity of flow)
3) Evaporation
: (addition of little quantity of glycerine)
