valves- building services

1. A valve is a device that regulates, directs or controls
the flow of a fluid (gases, liquids, fluidized solids, or
slurries) by opening, closing, or partially obstructing
various passageways. Valves are technically fittings ,
but are usually discussed as a separate category. In an
open valve, fluid flows in a direction from higher
pressure to lower pressure. The word is derived from
the Latin valva, the moving part of a door, in turn
from volvere, to turn, roll.

2. DIFFERENT TYPES OF VALVES

3. AIR VALVES
 These are also termed as the air relief valves. Some quantity of air is
contained in the flowing water and this air tries to accumulate at high
points along the water pipe. In order to provide an exit for such
accumulated air, the air valves are provided at summits along the water
pipe. The air valves should be located at points which are close to or
above the hydraulic gradient. If air valves are not provided, there are
chances for pipes to be air locked. The effective area of flow and
consequently the discharge through water pipe are greatly reduced due
to air locking.
 The provision of air valves along water pipe also helps in admitting air
quickly when vacuum occurs in water pipe due to sudden breakdown of
water pipe at low points.
 An air valve consists of a cast iron chamber, float, lever and poppet
valve. The chamber may be rectangular in shape. A poppet valve is a
valve that is lifted bodily.

4. AIR VALVE
SECTION OF AIR VALVE

5. CHECK VALVES
These are also known as reflux valves or non -return valves.
A check valve is an automatic device which allows water to
go in one direction only.
The reflux valve is invariably placed in water pipe which
obtains water directly from pump. When pump fails or
stops, the water will not run back to the pump and thus the
pumping equipment will be saved from damage. Similarly
at inter-connections between a polluted water system and a
potable water system, the provision of reflux valve will
prevent the entry of polluted water into the pure water.

6. SECTION OF CHECK
VALVES
CHECK VALVES

7. RELIEF VALVES
 These are also known as the automatic cut-off valves or
safety valves. The load on the spring is adjusted to the
maximum pressure.
 The relief valves are located at every point along the
water pipe where pressure is likely to bemaximum.
When pressure of water exceeds a predetermined
limit, the valve operates automatically and it will save a
particular section of water pipe before bursting of pipe
takes place.

8. RELIEF VALVES SECTION OF RELIEF VALVES

9. SCOUR VALVES
 These are also known as the blow off valvesor drain
valves or washout valves. These are ordinary sluice
valves which are located at dead ends and
depressions or lowest points in mains. They are
operated to remove sand or silt deposited in the
water pipe. They are operated with hand and
closed down as soon as clear water is seen passing
through them.

10. SCOUR VALVES

11. GATE VALVES
 These are also known as the gate valves or shut off valves or stop valves.
These valves control the flow of water and are helpful in dividing the
water mains into suitable sections. They are generally placed at a
distance of about 150 m to 200 m and at all junctions. For long straight
mains, the sluice valves can be installed at a distance of about 1 km also
to divide the pipe in different sections. The raising or lowering of valve
is carried out by rotating the handle from top. The installation of sluice
valves is very much useful in case of intermittent system of supply of
water.
 Stop cocks
 These are small sized sluice valves and they are installed in service
pipes serving the bib cocks. They operate on the same principle of
sluice valve and they are usually used up to sizes of about 50 mm. They
are placed on water pipe leading to flushing tanks, wash basins, water
tanks etc.

12. SECTION OF GATE
VALVES
GATE VALVES

13. FLAP VALVES
 A protective device installed in a drainage system to guard
against the effect of back flooding caused by surcharge.
 A flap valve is simple, one-way valve that allows the flow of gases
or fluids in one direction while preventing flow in the opposite
direction. The valve accomplishes this objective with a spring
loaded or weighted flap placed across the opening of a pipe,
tube, or duct. The valve flap releases in the direction of the
desired flow and is either forced open by the flow or by remote
means.
 Whenthe flow ceases or the remote actuation releases, the spring
or weight of the flap closes it against a seal, effectively preventing
fluid or gas from flowing back into the pipe. The flap valve also
prevents undesirable foreign objects from entering the pipe or
channel to which it is attached.

14. FLAP VALVES

15. FLUSH VALVES
 A flush valve is a mechanism used to flush a toilet or urinal.
The valve and associated hardware are located within the
toilet tank or in the body of the urinal. Most toilets have a
lever or push button activator, which is used to operate the
flush valve.
 A standard flush valve uses a rubber flapper to hold fresh
water within the toilet tank, though some older models
may use a ball rather than a flapper. As the user flushes the
toilet using the lever, a chain connected to the lever raises
the flapper at an angle. When the flapper is raised, the
fresh water from the tank rushes down into the toilet bowl.
This forces the existing water and waste material down
through the S-shaped pipe at the base of the toilet.

16. FLUSH VALVES
SECTION OF FLASH VALVES

17. BALL VALVE
 A ball valve is a form of quarter-turn valve which uses a hollow,
perforated and pivoting ball (called a "floating ball") to control
flow through it. It is open when the ball's hole is in line with the
flow and closed when it is pivoted 90-degrees by the valve
handle. The handle lies flat in alignment with the flow when
open, and is perpendicular to it when closed, making for easy
visual confirmation of the valve's status.
 Ball valves are durable, performing well after many cycles, and
reliable, closing securely even after long periods of disuse. These
qualities make them an excellent choice for shutoff applications,
where they are often preferred to gates and globe valves, but they
lack their fine control in throttling applications. The ball valve's
ease of operation, repair,

18. SECTION OF BALL VALVES
DIFFERENT PARTS OF
BALL VALVE
BALL VALVE

19. FOOT VALVE
 Description
 Foot valves are a type of check valve and are placed at the pump’s wet
well. Unlike other valves, a foot valve is created with a larger flow area
than the actual pipe size to make sure that there is less head loss. Foot
valves are either made of PVC plastic or stainless steel, and they are
known for keeping the continuous presence of suction within the
pump.

 Function
 Foot valves are used to maintain hydraulic pressure to keep the water
flow in accordance with the given settings or configurations. There are
instances where the pressure can actually pop the valve out and cause
major leakage; thus, it is important to use the right kind of material in
the tubing to be able to support the force within the valve.


20.  Features
 Being an important part of a centrifugal pump, foot valves come with
easily manageable features. Most foot valves are designed with a self-
tapping male and female threads to ensure easy installation; internal
balls for quick sealing and valve reaction; and flexibility to fit various
types of water pump uses, such as well development and volatile
organic compounds sampling and purging. Although they are cheaper
to use, as compared to other valves used to prime a pump, foot valves
are usually made up of heavy duty cast iron and bronze, as well as PVC
(depending on the type) so that they will last longer while submerged
in the water.

 Types
 There are three types of foot valves. The micro-flow system valves are
used in direct push technology micro wells and multi-level well
installations. These are usually made of stainless steel and are either of
fluorotherm (FEP) or high-density polyethylene (HDPE) tubing. The
high-flow system valve is used on 2-inch wells or larger and can stand
high pumping rates and very deep wells. On the other hand, low-flow
system valves are used in small diameter piezometers, which lift up to
100 feet of water.

21.  Support
 Foot valves usually come with surge blocks. A surge
block is a tool used to press the body of a valve to
remove the residues that may block smooth flow of
water within the pump during operation. It also helps
the valve expand while being used, thus enabling the
presence of increased pressure without causing
damage to the valve itself.

22. SECTION OF FOOT VALVE
FOOT VALVES

24. SOURCES
>>WATER SUPPLY AND SANITARY ENGINEERING
-RANGWALA
>> INTRODUCTION TO SERVICES
>> WIKIPEDIA