Explanation: There are two types of valves which are commonly used for domestic water supply. These are the globe valve and gate valve. A gate valve offers less resistance to the flow of water than the globe valve and is preferred over the globe valve where the resistance to the water flow is to be kept at the minimum. A gate valve controls the flow of water equally well from either direction.

Explanation: The materials used to make storage tanks are mild steel pressed plates, stone or brick masonry and reinforced concrete. A storage tank can be situated either at the roof level or at the ground level or both the levels.

Explanation: The various components of a storage tank are outlet pipe, inlet pipe, overflow pipe, ball valve, scour pipe, etc. A scour pipe is used to clean the tank periodically.

Explanation: According to the Indian Standard code recommendations, the flushing storage capacity for factories and workshops is 180 litres per urinal seat and 900 litres per W.C. seat. For cinemas and public assembly halls, it is 360 litres per urinal seat and 900 litres per W.C. seat.

Explanation: In a house drainage system, the pipe through which human excreta flows is called the soil pipe. The size of the soil pipe commonly used in house drainage is 100 mm.

Explanation: In a house drainage system, the pipe which is used to preserve the water seal of traps is called anti-siphonage pipe. The vent pipe is provided to serve the purpose of ventilation of the system. The waste pipe carries only liquid waste. Rainwater pipe carries only rainwater.

Explanation: A trap is a bent fitting which always remains full of water, when provided in a drainage system, thus maintaining a water seal. The strength or effectiveness of a water seal is represented by its depth. Effectiveness of the trap increases with the depth of the water seal.

Explanation: A trap is used to prevent the passage of foul air through it though it permits the sewage to flow through it. A trap should be cheap and readily available. It should be self-cleansing and simple in construction. A trap should be of non-absorbent material.

Explanation: Traps are classified into floor traps, gully traps, grease traps, silt tarps and intercepting traps according to their use. A floor trap is commonly called nahni trap. It is used to collect wash water from kitchens, floors and bathrooms.

Explanation: An intercepting trap is provided at the junction of the house drain with the public sewer. The opening at the top of the intercepting trap is called the cleaning eye. It is also called a rodding arm. It has a tight-fitting plug and is used for frequent cleaning of the trap.