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
6xDWF
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