Monday 20 January 2020

What is the Butterfly valve? - A Complete Guide for Engineer


Valves control liquid flow by allowing, obstructing, or partially allowing the flow of liquid in piping systems. It is necessary to install high-quality valves in pipes. API accredited valve manufacturing Camtech Company based in UAE which deals in the manufacturing of high-quality valves. There are many types of valves, but here we will discuss Butterfly valves.



The butterfly valve is a quarter-turn rotary valve, which means that it requires a quarter turn from closed to open position. Butterfly valves are used to start, stop, or regulate the flow of liquid in pipes. Due to compact size and lightweight design, butterfly valves are used in pipes with limited space. Butterfly valves may have gearing, wrench, or hand-wheel operated mechanism.

Parts of a Butterfly Valve

The body of the butterfly valve is circular which houses a round disc. Other parts are soft seats, shaft, top and bottom shaft bearings, and stuffing box. The valve body which is installed between pipe flanges can have flanged, wafer style, or lug design. Lug and flanged design butterfly valves come in a plethora of sizes and are easily installed. Wafer style design butterfly valves, on the other hand, come in NPS 12 size or smaller.

Types

Low-pressure butterfly valves or concentric butterfly valves are used in low temperature and low-pressure systems. When the valve is open, the disc is positioned parallel to the flow in the middle, which divides the flow into two halves. The maximum temperature that the valve can withstand depends upon the material of the resilient seats. 

The resilient seats can either be lined or unlined. The materials which are commonly used for lining resilient seats are Neoprene, Hypalon, Fluorcel, Buna N, Viton, EPDM, and TFE.

High performance or eccentric butterfly valves are other types of butterfly valves. In this type of butterfly valve, the disc is offset from the centre of the valve. The shaft is also offset from the centre of the disc. This Camtech director Dhananjay Choudhary design enables the disc to move eccentrically away from the valve seat or towards the valve seat. As a result, the friction between the surface of the disc and valve seat is reduced, which prevents wear and tear of both the disc and valve seat.

How does the butterfly valve regulate flow?
The disc of the butterfly valve is attached to a stem that is operated by an actuator present outside the valve. The actuator can be connected to a remote-control mechanism, automatic mechanism, or a manual lever. The disc is turned and blocks the flow when the valve is closed. When the valve is opened, the disc rotates a quarter turn and provides passage to the liquid. 

The disc is either perpendicular or parallel to the flow, and the flow can be regulated by adjusting the disc. Since the disc is always present in the flow, the pressure drop is high.

Applications

Butterfly valves are used in vacuum services, high pressure and high-temperature water and steam services, food processing, chemical processing, pharmaceutical processes, compressed gas or air applications, and much more.

What is cryogenic valve? How it works?


If we are aware of working of valves, proper usage of valve can help in achieving results in systems. A valve is designed to control or regulate the flow of fluid (air, liquid) by opening, closing or partially obstructing the passageways. Valves are of various types performing different functions in different types of systems. One of such kinds is Cryogenic valve.


As word cryogenic suggest, it is behavior of materials at very low temperature. Knowledge of cryogenic temperature range is important before selection of valve type. Cryogenic valves are constructed to be used in very cold temperature to control the flow of fluid. Cryogenic valve is one of the most crucial components of cryogenic industry. Certain gases are considered to be cryogenic and leakage of such cryogenic gases can be expensive and harmful. Cryogenic valve can provide tight shutoff and so are used to store and transport cryogenic gases safely

Cryogenic valves are mainly used by companies that work with liquefied natural gas or compresses Natural Gas. Cryogenic valves are used in applications dealing with liquefied gases such as liquid nitrogen, liquid helium. Due to the unstable nature of these liquefied gases, it is important to know the working of cryogenic valves will help to store these products right.

Cryogenic valve is designed such that it can react to high pressure pushing the valve to open position so that it will allow flow the gas through the passageway. Flow will continue until the pressure again decreases. When the pressure decreases the valve swings to closed position. The Cryogenic valve is kept closed to avoid leakage of the stored gas. The seal of cryogenic valve helps to provide tight shutoff. While building the cryogenic valve it should be taken in note that the material used while building would come in contact with the cryogenic gases and it may react with the material used while building valves resulting in damage of valve. Non elastomeric seals make good option for Cryogenic valves.

For construction of body of Cryogenic valve brass and stainless steel can be considered. While constructing a cryogenic valve , there is no specific guideline to select the valve type . Based on the application where cryogenic valve may be used , valve type should be selected. Each valve type has unique characteristics and valves types are Globe valves , Ball valves , Top entry ball valves , Gates Valve, Butterfly valve can be considered while building a new cryogenic valve. 

Cryogenic Globevalve are spherical in shape and have internal movable disc. These cryogenic valves offer greater reliability but are susceptible to moisture. Cryogenic Ball Valve uses the ball as the obturator. The valve provides good flow characteristics but needs  wear and tear along its seals and ball .They can be used in applications where unrestricted flow is expected. 

Top Entry Ball Valve is similar to Cryogenic ball valve but being the newer version maintenance becomes easy. The lack of mechanical joints makes it preferred option in fire safe applications. CryogenicGate Valves use wedge type gate as obturator and it is similar to ball valve but provides better flow characteristic. Even Cryogenic Gate valve needs wear and tear. Cryogenic Butterfly Valve belongs to quarter turn valve family which uses a circular disc at centre as obtuator. 

This disc allows butterfly cryogenic valve to be shorter in size making them lighter and cheaper option. Usage of any of these Cryogenic valves with proper knowledge will enhance application.
 Camtech Valves Dubai offers range of Cryogenic valves. In addition to Cryogenic valves , other wide range of valves are also available with Camtech Valves  Dubai which is one of the high quality valve manufacturing company based in Dubai, UAE .Dhananjay Choudhary is the Managing Director of Camtech Valves Dubai.

While buyer finalize with the Cryogenic valve option, it is important to consider safety of the valve. It is important that cryogenic valves undergo fire test as it is widely used in LNG industries. It should be considered that Cryogenic valves are built in Clean environment and it should be built in lubricant oil , germ and dirt free environment. As it will be working under Cryogenic temperature any unwanted material can react differently thus affecting the working of cryogenic valve .Buyer should request the support document for handling of Cryogenic valve which will make the usage of valve easy.