Types of Valves

Types of valves: when to apply which one?

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 it below.

First of all, an important side note must be given to this story. It is fair to say that there is no set instruction, roadmap or guide that easily indicates within each industry and application which type of valve should be used. 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. As long as this information is taken with a small grain of salt, it is possible to get a basic understanding of which valve is generally used when.

Below are the most common types of valves and when they are generally used (and when they are not).

The butterfly valve

The ball valve

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. By rotating 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 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.

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 particularly 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 on ball valves and Hanwel's offerings, see the ball valves section of this website.

The gate valve

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. Sliding gate valves are also available in various designs, depending on the exact requirements and wishes.

A shared advantage of all sliding 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.

The globe valve

The globe valve is similar to the gate valve in terms of linear operation. Both close the pipe by means of a spindle, via a linear motion (multi-turn). This is in contrast to the ball valve and butterfly valve, which make a rotary motion (quarter-turn). In a globe valve, a so-called globe is pushed down by a spindle into a specially designed seat. The design of the globe can be customized depending on the exact application but in almost all cases it is a flat disc in the shape of a flat cone.

Although the operation is similar to a gate valve; the primary function is not. Due to the shape of the cone, a globe valve is able to close very precisely and thus achieve a fairly linear flow. This makes globe valves extremely suitable for control and modulation. Depending on the materials used, globe valves are also suitable for very high pressures. Globe valves are therefore often used as control valves and/or high-pressure valves. The advantage is clearly the precision in terms of closure and the linearity of the pressure loss.

A disadvantage of a globe valve can be that it does not create a full orifice (not full-bore) and that the design is quite expensive compared to a simple gate, butterfly or ball valve. A very compact version of the globe in the form of a needle / narrow cone is also called a needle valve. The needle valve is mostly used for very small diameters or for very precise regulation. For large diameters, both the globe valve and the needle valve are unsuitable.

The Diaphragm Valve

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. 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 relatively 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.

On request, Hanwel can supply diaphragm valves, our specialists will be happy to help you with this.

The check valve

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.

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, which means that an additional valve that can be operated is required to control the process.

For more information about check valves and Hanwel's product range, see the check valves section of this website.