Asbestos pipes are joined by means of
-
flanged joint -
flexible joint -
dresser coupling joint -
simplex joint -
socket and spigot joint.
Efficiency of removing bacterias from raw water by a slow sand filter, is
-
80% to 81% -
85% to 86% -
90% to 97% -
98% to 99%.
For plain chlorination of water, the quantity of chlorine used, is
-
0.1 mg/litre -
0.2 mg/litre -
0.3 mg/litre -
0.4 mg/litre -
0.5 mg/litre.
Pick up the correct statement from the following :
-
Due to boiling, the bacterias present in water can be destroyed -
Lime may be used for softening hard water -
Excess lime when added to water, raises the pH value of water -
the bacterias do not survive in water having pH value exceeding 9.5 -
All the above.
The superimposed load transmitted to the pipe, is generally evaluated by Bousiness formula
The type of joint generally used in cast iron pipes, is
-
socket and spigot joint -
flanged joint -
dresser coupling joint -
flexible joint -
all the above.
The flow of water gets retarded, in
-
settling tank -
sedimentation tank -
clarifer -
sedimentation basin -
all the above.
Pick up the correct statement from the following :
-
The precipitation during its travel in atmosphere dissolves certain gases -
Rain water which percolates through the ground, is free from suspended materials -
Under ground water may dissolve minerals and salts present in the earth's layers -
Small quantities of iron, calcium and magnesium dissolved in water, may be useful for human health -
All the above.
For the prediction of future population of a city, the factor to be considered, is
-
births -
deaths -
migrants -
all the above.
Rapid sand filter
-
should be preceeded by coagulation and sedimentation -
uses rapid sand as filter media -
is used after slow sand filtering has been done -
can combine disinfection also.
The type of joint generally used in cast iron pipes, is
-
socket and spigot joint -
flanged joint -
dresser coupling joint -
flexible joint -
all the above.
In a well planned city, the layout of distribution pipes generally adopted, is
-
grid-iron system -
interlaced system -
reticulation system -
all the above.
Detention time for plain sedimentation tank usually ranges from
-
2 to 4 hours -
4 to 8 hours -
6 to 10 hours -
8 to 12 hours -
12 to 16 hours.
Abyssinian tube well is a special type of
-
slotted type wells -
cavity type wells -
strainer type well -
none of these.
De-chlorination is followed by
-
post-chlorination -
pre-chlorination -
double-chlorination -
super-chlorination.
Water may contain
-
bicarbonate alkalinity -
carbonate alkalinity -
hydroxide alkalinity -
caustic alkalinity -
all the above.
The intake opening is generally covered by a screen to prevent entry of debris etc. and its level is kept
-
at the level of water of the source -
at the bottom of water of the source -
at about 2.5 m above the bottom -
none of these.
Surcharge storage zone of a reservoir, is
-
below dead storage -
between dead storage and useful storage -
above useful storage -
also known as valley storage.
Air inlet valve in water mains, is generally provided at
-
summit of the pipe -
upstream of sluice valve -
down stream of sluice valve -
valley of the pipe -
both (a) and (c) of above.
The maximum permissible chloride content in treated water of public water supplies should not exceed
-
50 P.P.M. -
100 P.P.M. -
150 P.P.M. -
200 P.P.M. -
250 P.P.M.
An ideal sand for filters should be
-
free from dirt and other impurities -
uniform in nature and size -
hard and resistant -
all the above.
Pick up the correct statement from the following :
-
Large solids carried along the river bed, is known as bed load -
The bigger suspended particles get deposited in the head reaches of the reservoir -
The fine sediment deposits are generally near the face of the dam -
Deposition of sediment in the reservoir, reduces the capacity of the reservoir -
All the above.
Pick up the correct statement from the following :
-
Copper pipes are highly resistant to acidic and alkaline water -
Wrought iron pipes are lighter than cast iron pipes -
Wrought iron pipes corrode quickly and are less durable -
Wrought iron pipes coated with zinc, are called galvanised iron pipes -
All the above.
Air valves are generally provided in pressure pipes of water supply
-
at pipe junctions -
at summits -
at low points -
near service pipes.
Chlorination of water does not remove
-
ammonia content -
B.O.D. -
organic matter content -
dissolved oxygen.
The bed slope in slow sand filters, is generally kept
-
1 in 50 -
1 in 75 -
1 in 100 -
1 : 200
The valve fitted closely in a recess against an opening in a pipe, is generally
-
wedge shaped circular disc -
spherical disc -
parallelopiped disc -
conical shaped circular disc.
Pick up the correct statement from the following :
-
The ratio of the total sediment deposited in the reservoir to the total sediment flowing in the river, is called trap efficiency -
The ratio of the reservoir capacity to the total inflow of water in it, is generally called capacity inflow ratio -
Small capacity reservoirs on large rivers generally, silt less -
Large capacity reservoirs on small rivers generally silt more -
All the above.
Most important method for calculating discharge for planning a water supply project, is
-
velocity area method -
weir or spillway method -
use of venturi-meter -
using power plant consumption -
none of these.
A pressure conduit carrying water beneath a stream or a canal, is known as
-
sag -
depressed pipe -
inverted syphon -
all the above.