Dust control in traffic signals using water sprayers.
Dust control in
CEG, Anna University.
Environmental Problems in cities
Control using sprayers
Factors affecting efficiency
Advantages and disadvantages
1. Industrial air pollution.
2. Intensive automobile exhaust.
3. Improper waste management.
PROBLEMS IN CITIES?
Short term effects:
• Irritation to eye, nose and throat.
• Respiratory problem such as bronchitis,
• Head ache, nausea, etc…
Long term effects:
• Chronic respiratory diseases,
• Lung cancer,
• Damage to heart, brain and nerves.
EFFECTS OF DUST
Open grounds, etc…
WHERE THE DUST IS FOUND
IN CITIES ?
AS AN ENGINEER, HOW CAN WE CONTROL THESE
WATER SPRAYERS IN TRAFFIC SIGNALS:
“ Spraying of water subsides dust. “
Water sprayers can be attached in the traffic
signal posts, in which it can spray water when
the signal is turned red.
Dust consists of solid particles larger than 1 µm in diameter.
Dust particles smaller than 10 µm are the most dangerous
since they are respirable.
These are the dusts which we commonly find in roads
How dust is generated in roads?
• Dust carried from vehicles from other places
• Automobile emissions
• Through wind
“ Very fine water drops collide with dust particles in the air,
to form agglomerates of dust and water which are too heavy
to remain suspended in air. “
Hence the agglomerates settle down which ultimately means
that the dusts settle down.
The sprayer nozzles should be fitted to the posts in the
High pressure pipeline water supply is connected to the
A time dependent sensor should be fixed along with that
such that the spraying starts whenever the signal turns
red, and it ends just before the signal turns green.
This ensures that the water sprayed will not fall on
THREE TYPES OF WATER EJECTORS
1. Water sprinklers
2. Water sprayers
1) Drop size:
Drops that are too large will not collide with the finest and
most hazardous dust particles.
Drops that are too small evaporate quickly and release the
Nozzles that produce a misty rain and wet fog consisting of
drops in the 10 to 100 µm range are most effective.
Collision is most likely to occur when the size of drops are 2
to 4 times bigger than dust particles
FACTORS AFFECTING EFFICIENCY OF THE
TIME FOR PARTICLE TO SETTLE
DOWN FOR 10FT ( sec)
2,000 to 5,000 Heavy rain 0.9 to 0.85
1,000 to 2,000 Intense rain 1.1 to 0.9
500 to 1,000 Moderate rain 1.6 to 1.1
50 to 500 Light rain 5 to 1.6
10 to 50 Misty rain 16 to 5
5 to 10 Wet fog 26 to 16
1 to 5 Dry fog 100 to 26
Type of droplets, size and time taken to settle
2) Spray angle: A spray angle between 265°and 275° offers the
best coverage without compromising the creation of
3)Drop velocity: The drop velocity should be very high to get a
good efficiency. If it is less, then the water spread area will
4)Water pressure: The water pressure at the nozzle should be
very high inorder to attain a very high drop velocity.
The nozzles should be checked and cleaned regularly so that
the holes are not blocked by dust particles.
The angle and tightness of the sprayer should be checked for
exact wide spread area.
Timing of the sprayer should be checked to coincide with the
Effective dust control method.
Spraying is automatic.
Respirable dusts are made settle
Maintains a nourishing weather.
Not necessary to use very pure water
Very less labour requirement.
Economical, once the system is installed.
Proper maintenance needed.
Stable water source is required.
Not suitable for countries which
have very less temperature.
Installation charges may be high.
Hand sprayers are used in agriculture for fertilizer spraying.
Dry fog sprayers are used in cement factories for dust
APPLICATION OF WATER SPRAYERS IN OTHER
• For controlling dust pollution in Indian cities, very minimum
efforts have been taken from the Government side.
• If we implement these water sprayers, it will be a very
effective as well as economical way to solve the pollution
• So lets widen our scope beyond agricultural field towards
environmental conservation to create a dust free city.