Types of valves: when to apply which one?

Types of valves: when to apply which one?

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From ball valves to butterfly valves and gate valves to globe valves; there are several types of valves. Each type has its own functionality, advantages and disadvantages. When do you apply which valve? Read about it below.

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First, an important note must be given to this story. It is fair to say that there is no set instruction, roadmap or guide that simply indicates which type of valve should be used within each industry and application. The differences between the various applications are simply too great to point to universal solutions. Within this restriction, however, we can indicate the global comparisons and contrasts between the types. Thus we can point out the most common applications in which these types are used. Thus, as long as this information is taken with a small grain of salt, a basic understanding of which valve is generally used when can be gained.

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The butterfly valve

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We start with the butterfly valve because it is the most common valve in the industry. The reason is simple: in its standard design, the butterfly valve is often the cheapest and simplest valve. In addition, the butterfly valve is available in very large dimensions. A butterfly valve is a valve that shuts off all or part of the flow of a liquid or gas with a disc that rotates on its axis. Rotation through an angle of 90° moves the butterfly valve from open position to closed position or vice versa. Because the design is quite simple, relatively few parts are required and the complexity of the components used is quite low.

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Combined with the fact that little material is required, this makes the butterfly valve a low-cost, lightweight and compact solution. The simplest version is the centric version with a rubber cuff or, in the case of corrosive media, the version with plastic cuff. As temperature range and pressure range requirements become more stringent, a double-, triple-, or even quadruple eccentric version can be used. The disadvantage of a butterfly valve is the butterfly or disc itself, which forms an obstruction to the medium. This can cause unwanted pressure losses and accumulation of the medium if it contains solids. For these reasons, a different valve may be chosen. For more information on butterfly valves and Hanwel's offerings, see the butterfly valves section of this website.

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The ball valve

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After the butterfly valve, the ball valve is the most common valve in industry. The reason for this is the same as for the butterfly valve: a ball valve is a compact, lightweight and relatively inexpensive solution to regulate a medium. A ball valve is a valve that shuts off all or part of the flow of a liquid or gas with a pierced ball that rotates perpendicularly on its axis.

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By turning the ball 90°, the valve goes from open position to closed position or vice versa. In this, a ball valve has one major advantage over a butterfly valve: it has no obstruction in the orifice, which means it has less pressure loss than a butterfly valve and therefore less ability for the medium to accumulate. If a full bore version is chosen instead of a reduced bore, this pressure loss is even further reduced. Ball valves are available in various designs and materials and can be applied with a wide variety of seals. This makes them applicable in a very wide temperature and pressure range.

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However, the ball valve has two major disadvantages: because of its design, the cost of the ball valve increases significantly as the pipe diameter increases. The costs accumulate especially from DN150 orifice onwards. In addition, the most commonly used design - the floating ball design - has a number of dead spaces under the ball in which the medium can accumulate. Selecting a trunnion design prevents this, but this results in relatively high costs.

In short: for larger pipe diameters and for a medium where dead spaces are undesirable, the ball valve is less suitable and one can opt for another valve. For more information about ball valves and Hanwel's offerings, see the ball valves section of this website.

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The gate valve

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Although butterfly valves and ball valves are the most commonly used valves in industry, they have both a shared disadvantage and a shared danger. When the medium contains solids such as sludge, fibers, pulp, pebbles, etc., the danger of accumulation arises and both the ball valve and butterfly valve may jam. The gate valve provides a solution for this. In a gate valve, a gate valve is pushed into the path of the flowing medium by means of a spindle. The valve opens fully and, with its weight, completely seals the pipe. With a knife edge design, this involves cutting through remaining parts of the medium to ensure complete tightness.

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Gate valves are also available in a variety of designs, depending on the exact requirements and needs. A shared advantage of all gate valves is their ability to properly seal a thick, dirty and slurry-forming medium. A shared disadvantage of all gate valves is the fact that they are relatively large and heavy and thus relatively expensive compared to other valves. Also, opening and closing times are often considerable because of the linear motion required. The gate valve is generally a more expensive solution than a butterfly valve and ball valve and is thus used for specific applications in which the above valves are inadequate. For more information about gate valves and Hanwel's offerings, see the plate valves section of this website.

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The diaphragm valve

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A diaphragm valve consists of a steel body fitted with a rubber diaphragm that is flattened by means of a spindle in a linear motion, thus sealing the medium. This relatively simple design means that few rotating or moving parts are required and thus there are relatively few wear and tear parts. In addition, diaphragm valves generally achieve full bore, which minimizes pressure loss.

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The main application for diaphragm valves are processes with highly abrasive media such as the cement industry and mining. The diaphragm, which is often made of an elastomer, is quite insensitive to wear and tear and can be easily replaced. The disadvantage is that these valves can only be used for open/close applications and regulation is impossible. In addition, diaphragm valves are unsuitable for high temperatures and pressures, vacuum processes and gases. Finally, diaphragm valves become significantly more expensive once the dimensions become larger.

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The check valve

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The check valve is an umbrella term for all valves that do not open and close by means of a manual or automatic actuator but are opened and closed by the medium itself. There are various versions of these: globe valves, swing check valves, dual plate valves, disco valves, tilting disc valves, etc. All check valves share the principle that the valve - in whatever version - is pushed away when the medium enters the valve upstream.

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When the medium is completely through the valve and there is no more upstream pressure, the valve closes. The same happens when the medium flows back toward the valve. Because of this, check valves are commonly used as safety for protecting critical components such as pumps. This function is also the great advantage of the check valve: it protects critical components automatically without the need for any action. However, this can also be a disadvantage: in most cases, a check valve cannot be operated, so an additional valve that can be operated is required to control the process.

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Flue gas valves

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A flue gas valve is a valve specifically designed to shut off low-pressure flue gases. Flue gas valves are available in a variety of designs: butterfly valves, slide valves, louvered and multi louvered valves, bypass valves and check valves. In particular, this category is distinguished by a high focus on temperature suitability and low to no focus on operating pressure. As a result, flue gas valves are generally of thinner construction than valves conforming to PN10 or 150lbs. The advantage of this construction is low cost combined with large diameters. For more information on flue gas valves and Hanwel's offerings, see the flue gas valves section of this website.

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