How to choose the right valve ?

1、How to choose the valve?

Before choosing a valve, you need to determine its purpose. Will the valve be used to regulate a fluid or to stop the flow of a fluid?

Then you need to determine the type of media circulating in the system: is it gas or liquid? Is the medium corrosive, chemically neutral, a food product or a medical fluid requiring special sanitary conditions?

When it comes to the valve's operating system, it is necessary to know whether it is manual or automatic. In the first case, someone must be on site to operate the valve, while in the other case, the valve can be operated remotely, for example from a control station.

Finally, it is important to know how the valve will be integrated into the system and the type of assembly or mounting that will be used, especially if it needs to be welded, bolted through a flange or screwed in.

Once these different elements have been identified, you can focus on the technical characteristics of the installation, particularly the flow and pressure, used to size the valve.

2、How to size a valve?

In order to calculate the size of a valve, you need to know the parameters related to the operation of the circuit.

Pressure is an important factor that must be taken into account, on the one hand to avoid under-sizing the valve, which could lead to problems of leakage or rupture, and on the other hand to avoid over-sizing the valve.

The operating temperature needs to be determined, i.e. the temperature of the circulating medium, as well as the ambient temperature around the valve body.

It is important to know the extreme temperatures that the valve needs to withstand in order to be able to select valves that can be used to operate under these conditions, especially the materials used to manufacture the valve body, the closing system and the seals.

The operating pressure, i.e. the pressure at which the medium circulates through the valve.

The flow rate and velocity of the fluid. Flow rate and rated velocity are essential elements to help you select the right valve, especially for regulating that flow. The flow coefficient (Kv) is a theoretical value specified by the manufacturer to calculate the nominal flow rate of the valve. It can be expressed in liters per minute (l/min) or cubic meters per hour (m3/h). The valve manufacturer provides charts to determine this factor based on the desired flow rate and nominal diameter.

The nominal diameter (DN) of the circuit in which the valve is located. This is essential to avoid oversizing the valve, which can lead to unstable operation of the equipment, or undersizing, which can lead to large pressure drops and rapid valve damage.

3、What are the main types of valves?

There are different types of valves that can more or less fulfill your needs. If you need to stop the circulation of a fluid, we recommend that you choose a detent valve, such as a globe valve, knife gate valve or gate valve.

If you need to control the flow of fluid, it is best to choose a control valve, such as a needle valve, globe valve, piston valve or butterfly valve, all of which provide good throttling.

The choice of valve also depends on the flow rate, pressure and type of fluid being transported, as this will determine the material used for the valve.