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.

VALVES

DIFFERENT TYPES OF VALVES

AIR VALVESThese 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.

AIR VALVE

SECTION OF AIR VALVE

CHECK VALVESThese 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.

SECTION OF CHECK VALVES

CHECK VALVES

RELIEF VALVESThese 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.

RELIEF VALVES SECTION OF RELIEF VALVES

SCOUR VALVESThese 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.

SCOUR VALVES

GATE VALVESThese 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 cocksThese 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.

SECTION OF GATE VALVES

GATE VALVES

FLAP VALVESA 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.

FLAP VALVES

FLUSH VALVESA 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.

FLUSH VALVESSECTION OF FLASH VALVES

BALL VALVEA 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,  

SECTION OF BALL VALVES

DIFFERENT PARTS OF BALL VALVE

BALL VALVE

FOOT VALVEDescriptionFoot 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.

 FunctionFoot 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.

 

FeaturesBeing 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.

 TypesThere 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.

SupportFoot 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.

SECTION OF FOOT VALVE

FOOT VALVES

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