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Environmental (81-100)

Updated: Apr 10, 2020

81.The type of valve which is provided to control the flow of water in the distribution system at street corners and where the pipe lines intersect is

sluice valve


82. The type of valve which allows water to flow in one direction but prevents its flow in the reverse direction is reflux valve


83. Scour valves are provided at every depression and dead ends to drain out the waste water that may collect there


84. A sewer that receives the discharge of a number of house sewers is called

lateral sewer


85. A pipe conveying sewage from plumbing system of a single building to common sewer or point of immediate disposal is called house sewer


86. For a country like India, where rainfall is mainly confined to one season, the

suitable sewerage system will be separate system


87. Average rate of water consumption per head per day as per Indian Standard is

135 litres


88. Sewerage system is usually designed for 25 years


89. Which of the following sewers is preferred for combined system of sewage ?

egg shaped sewer


90. The suitable system of sanitation for area of distributed rainfall throughout the year with less intensity is combined system


91. The water carriage system of collection of waste product requires treatment before disposal


92. If the time of concentration is 9 minutes, then the intensity of rainfall according to British Ministry of Health formula will be 40 mm/hr


93. The time of concentration is defined as

the time taken by rainfall water to run from most distant point of water shed

to the inlet of sewer + the time required for flow of water in sewer to the point under consideration


94. The specific gravity of sewage is slightly greater than 1


95. The self cleansing velocity for all sewers in India is usually 1.0 m/sec to 1.2 m/sec


96. The slope of sewer shall be given in the direction of natural slope of ground


97. The design discharge for the separate sewer system shall be taken as



98. The design discharge for the combined sewer system shall be taken as

rainfall + 2 DWF


99. The minimum and maximum diameters of sewers shall preferably be

15 cm and 300 cm


100. The main disadvantage of cement concrete sewers is

difficulty in transportation due to heavy weight

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