Day 30_LSGD_Public health- Terms, systems of sanitation

The term “self-cleansing velocity” in house drainage refers to —

• The minimum velocity at which suspended solids just start settling

• The minimum velocity that prevents deposition of solid matter

• The maximum permissible velocity in sewers

• The theoretical velocity of design storm flow

The “anti-siphon trap” is primarily installed to —

• Increase discharge capacity of the trap

• Prevent loss of water seal due to negative pressure

• Reduce odour transmission by water curtain

• Facilitate mechanical cleaning of blockage

The pipe which conveys foul gases from the drainage system to the atmosphere above roof level is the —

• Soil pipe

• Waste pipe

• Vent pipe

• Anti-siphon pipe

In a single-stack system of house drainage, the trap ventilation is —

• Provided at every floor

• Provided only at the terminal branch

• Provided through a separate vent stack

• Not separately provided

The connection between the house drain and public sewer is made through a —

• Cascade chamber

• Retention chamber

• Intercepting chamber

• Vacuum relief chamber

A disconnecting trap is provided —

• At every floor waste

• At the junction of house drain and municipal sewer

• Below each closet trap

• At every gully trap location

Which arrangement provides the highest degree of protection against foul air?

• Partially ventilated single stack

• Fully ventilated system (two-pipe system)

• Anti-siphon system

• Single stack system

In a high-rise multi-storey drainage design, vent pipe diameter is kept not less than the diameter of branch pipe mainly to:

• Reduce negative pressure

• Maintain gradient

• Comply with trap sizing

• Ensure hydraulic continuity of air column

The minimum gradient of 1 in 50 in branch drains is recommended mainly for:

• Reducing noise

• Increasing flow

• Ensure self cleansing velocity

• Gaining invert level

The pipe carrying discharge from water closets (WC)s is called (a)   .