What is a valve and what purpose does it serve?

A polybutylene shut off valve is a mechanical device that uses moving elements to partially or fully open or close the flow of a fluid to initiate, halt, or control the flow of liquids or gases. The installation of pipes, fittings, and pumps must be taken into consideration while discussing valves.

Minimum Diameter

When providing a valve to a client, it is crucial to understand the kind of fluid that will travel through it since some substances might be hazardous or harm the valve itself. For each fluid—gas and water are the two most common in plumbing—the best valve must be chosen.

The internal passage size (diameter) of a valve is the first item to be aware of. Nominal Diameter, or DN, is measured in millimeters and must match the pipe's diameter where the valve is fitted.

Two distinct valve types exist:

  • Whole Pitch, when the inner pitch is the same as the pipe's.
  • Reduced Pitch: The inner pitch's diameter is less than the pipe's. Reduced bore valves are those in which the pitch has been decreased by more than 5% relative to the DN.

Valve nominal pressure

The phrase "Working limits: pressure PN16" is mentioned in the catalogs, as can be seen. We discover that valves are made for various pressures when discussing pressures. The abbreviation PN is used to indicate the design pressure (Nominal Pressure). Bars or kg/cm2 are used to represent the nominal pressure (PN). The terminology used for DIN valves is called PN.

But take caution! The valve may not always function at this pressure, though. That indicates that for a brief period of time, that pressure is the most that it can endure without breaking.

Between 50% and 60% of the "nominal pressure" is often the "normal continuous operating pressure." Although working at full pressure is not recommended at all times, this is done for safety reasons.

Low pressure

We also need to understand the idea of pressure loss. In a basic approach, it may be argued that head loss is a consequence of the challenges that a fluid faces along its passage via pipes, fittings and valves. Because of all these challenges, a bigger pump is required to move the same volume of fluid through the installation.

Types of valves based on their function

Knowing the most crucial features of each type of valve is critical when choosing the most appropriate type for the intended service.

The ball valve

The rotation of a drilled sphere causes the ball valve to open and close. The fluid can travel through when this bore lines up with the pipe. On the other hand, the fluid cannot circulate when the bore is perpendicular to it.

The sphere rotates 1/4 of a revolution (90°), which causes the opening or shutting to happen very fast. Its speed, which is frequently praised as a quality, might result in a water hammer that has to be considered.

They have a very little pressure drop, need little maintenance, are bidirectional, and are small in size. Due to its affordable pricing, tightness, quick opening and shutting, simplicity of automation, and the numerous material combinations that may be utilized in them, ball valves have grown to be one of the most often used valves.

Door valves

This valve has many turns and closes the flow with a vertical disc with flat sides that moves perpendicular to the seats. Due to the rubber covering on this inner wedge, the sealing is excellent.

This sort of valve's gradual shutting ensures that water hammer will never occur. It is not recommended to control flow rates with this valve. Their construction makes it possible to repair the inner mechanism in the event of a breakdown without removing the valve from the pipeline.

The check valve

The use of check valves differs greatly from the applications previously discussed. A check valve is one that permits fluid to flow in one direction while blocking it in the other. For this sort of valve to function, there is always a mounting direction or location.

The purpose of a valve is to stop a fluid from returning through the pipeline after it has gone through the valve, not to stop a fluid's flow at will. They should always be put at the pump's outlet or downstream of a shut-off valve.

Controlling valves

Regulating valves are valves created specifically to regulate water flow. They feature an internal component with a handwheel that allows them to control the amount of water that flows through the valve.

This valve can be automatically regulated by coupling it to a head with a temperature-sensitive mechanism or an electrical signal, which opens or stops the water flow.

The so-called balancing valves may be included in this section. Balancing valves are in charge of generating the proper head losses to guarantee proper fluid distribution throughout the installation, depending on the features of the installation.

The fluid will tend to flow through the areas of an installation that have the lowest head loss if it is not balanced, which will cause certain terminal units to be overfed while others to have a flow deficit.