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A valve is a device that controls the flow of a fluid by opening, closing. Valve (in an open state), allows to flow the fluid from higher pressure to lower pressure.
Main Types of Valves
There are several type of valves each differentiated by its function and are used in different scenarios.
- Ball Valve
- Gate Valve
- Plug Valve
- Butterfly Valve
- Globe Valve
- Pinch Valve
- Disc Check Valves
Ball Valve Symbol
A ball valve operates in a quarter-turn and uses a hollow, pivoting ball to control the fluid flow. In open state, the ball’s hollow side is aligned with the flow and in the closed state, the ball is facing the fluid. The ball is rotated by the valve handle.
Ball valve is most commonly used in houses for plumbing works. This type of valve is mostly suitable for the pipes with less than an inch of diameter.
Gate Valve Symbol
Gate valve opens by lifting rectangular gate out of the fluid path. The gate opens and closed through a rotating wheel. These type of valves are mostly used in the pipes with more than 3 inch of diameter.
Gate valve are used where minimum obstruction is required. It has a strong sealing mechanism which makes it ideal in several industrial usages. These valves are widely used in high pressure water supply lines and high pressure of gas lines.
Plug Valve Symbol
Plug valve is an advanced form of Ball valve. The mechanism of plug valve is similar to a standard quarter-turn valve with several advancements. It uses a cylindrical gate instead of a ball gate.
Plug valve are used for hot liquid or steam. Thanks to its mechanical design that helps to bear high pressure and high temperatures whereas ball valve can’t be used for hot liquid or steam as it can melt the valve sealing which usually is made of silicon.
Butterfly Valve Symbol
Butterfly valve comes in several types, each has its own functions and implementation. As its name suggests, butterfly valve open like a butterfly. It comes with a gearbox and a rotating wheel.
The main benefit of this butterfly valve is that it can be easily adapted with process automation (electronically controlled).
Lug Style Butterfly Valve
In Lug style butterfly valve, the rotating liver is locked with a lug (handle). To open or close the valve, the Lug (handle) is pressed and then the liver can be rotated.
Flanged Butterfly Valve
Flanged butterfly valves are suitable for congested areas. The flanges are already attached to this type of valves and additional fittings are not required to install this type of valves. To buy these type of valves, you can visit Johnsonvalves.co and Nibco.com
Butt Welded Ends Types
Butt Welded Valves are installed using “butt type welding”. The inlet and outlet caps of the valves are designed to be welded. These type of valves can be installed with minimum instruction to the operator. Often used for autonomous processes where machines are supposed to weld using process automation.
Butterfly Valves seat types variation
Butterfly type valves also varies in the seat material. Some valves comes with soft seats (silicon, rubber, plastic etc) and some comes with metal seats (brass, mild steel, cast iron etc).
Global valve is similar to Gate Valve but it is more robust. When the valve is rotated to open the rod remains in the screw (like Screw Jack). These type of valves are mostly used for industrial purposes where heavy pressure and temperatures are used in the pipes.
Globe Valve Symbol
Difference between Gate Valve and Globe Valve
The main difference of globe valve and gate valve is the level of complexity in mechanical design. The globe valves are more robust, more advanced. Gate valve use a flat disc as its (sealing) seat whereas the globe valve is having a wedge shaped disc seal which performs as a cork.
One more difference is that the gate has its stopper disc in the Y axis (Top – down) and the Globe type has its stopper disc at X axis. This basic difference makes the globe valve irresistible to high pressure whereas the gate valve is more prone to leakage when used in very high pressures.
Pinch Valve Open, Closed and Throttling States
As suggested by its name, the pinch valve pinches (squeezes or release) a tube to close or open the valve respectively. The tube is made of good quality rubber that can easily pinched and when it’s released comes to its original position.
A Pinch Valve is an economical piece of equipment that works like a tap. It has an on/off function, to shut off, allow or control the flow of any media passing through it. The Pinch Valve is made up of three parts: Body / Housing. Internal rubber sleeve.
Pinch valve can also perform throttling (a process where pressure is increased by half-pinching the rubber pipe.
Pinch valves are mostly used where the liquids needs to keep completely isolated. It is used in medical equipments, clinical and chemical analyzers. They are also used in a wide range of other laboratory equipment.
Check & Foot Valve Symbol
Check valves are one-way (non-returning) valve. It is often installed at the bottom of a tube well, pit of water and also in the water geysers.
A seal is used with a spring, when water is pumped from one direction, the spring opens with the suction pressure. When the pump stops, the spring pulls the valve seat and automatically closes the valve.
Foot valve is similar to the check valve except it comes with a stainer which restricts solid chunks of garbage.