What are Pressure Control Valves?

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The valve used to maintain a regulated pressure in any continuous process is called a pressure control valve.

A pressure control valve is integrated into every hydraulic system. The system can be harmed when hydraulic pressure builds up. That is why there are pressure control valves for protection. They control the system and avoid any overheating, power waste and damage.

In this article, you will find the basic applications of these valves and how it works. You will also get to know about different types of pressure control valves. Read the whole article to have a better understanding. Let’s get started.

Why is a Pressure Control Valve Needed?

There are two main requirements, pressure relief and pressure regulation. These will help the system to gain pressure control. Any restriction in fluid flow will result in a pressure build-up in the valve.

If you do not monitor the system’s pressure, it will damage the numerous systems further. Consequently, your money, as well as time, will be wasted.

The best example is using a line relief valve to restrict the maximum system pressure. Hydraulic systems contain these valves as the safeguard.

Thus, to avoid any wastage in a non-action timespan, circuit designers use smart systems to overcome maximum pressure. The hydraulic system’s actuator force (equal to pressure x area) is controlled by such smartly designed pressure control valves. It also helps to choose the required pressure levels to operate a specific machine.

Functions of Pressure Control Valves

In various fields, pressure control valves play a major role in systems. Before going into this, we will summarize the basic functions of these valves.

Pressure control valves help to reduce or limit the pressure whenever needed in the system. In other words, you can say unloading the pump. You can also set backpressure if your system requires it. In a circuit, the pressure of any selected portion can be controlled.

When a required pressure in any system is achieved, these valves will signal to avoid overpressure problems and maintain safety.

Moreover, pressure control valves assist the circuit’s actuators in their operation sequence. These valves also transfer pressure levels from the main circuit to a sub-circuit with lower pressure.

Useful Applications of Pressure Control Valves

Following are some most recognized applications of pressure control valves.

• These valves help to lower the pressure of cooking water.
• They work like air compressors in certain machines.
• These valves are majorly used in the field of aerospace and aircraft.
• They play an eminent role in cutting and welding with oxyfuel.
• Pressure control valves are also important in mining industries, automation, and tooling.
• Moreover, they are used in pressure reactors in the flowing inlet of load.
• These pressure control valves are useful for bulk storage and transporting liquified petroleum gasses.

Different Types of Pressure Control Valves

According to the working principle PCV or pressure control valves are categorized into four main types: Pressure Relief Valves, Counterbalance Valves, Sequencing Valves, and Pressure-Reducing Valves.

  1. Pressure Relief Valves

This valve is also known as PRV. These valves are used to limit or adjust the system’s pressure. The whole procedure, a certain instrument, or equipment could break down due to the pressure building up. This kind of damage can be stopped with the help of a pressure relief valve. These valves lessen the additional fluid flow and limit the maximum pressure in rising pressure.

In simple words, it relieves the overpressure of liquid in the system. This valve will remain closed with the aid of a spring when the system is working under normal pressure.

As the pressure builds in the vessel due to fluid, it will push the spring. A valve will be opened when pressure or force reaches setpoint pressure. That is the maximum system pressure for normal operation.

The valve will be opened gradually when fluid pressure crosses this setpoint pressure value. As a result, the pressure will start to drop to its normal value. You can change the spring force by adjusting the screw to have different setpoint values.

  2. Sequencing Valves

Sequencing valves are hydraulic system components that govern the operating sequence of several hydraulic cylinders or motors. They’re sometimes referred to as sequence valves or unloading valves.

A sequencing valve is often installed between two or more hydraulic actuators (cylinders or motors) and a directional control valve in a hydraulic circuit.

When the pressure in the first actuator reaches a predefined level, the valve opens to enable fluid to flow to the second actuator. It guarantees that the first actuator finishes its stroke or action before the second actuator starts moving.

Sequencing valves are often employed in applications requiring precise hydraulic operation sequencings, such as material handling equipment and machine tools.

They can also protect hydraulic systems from damage by avoiding excessive pressure accumulation.

Sequencing valves come in various configurations, including pilot-operated, mechanically operated, and electrically driven valves. The application and the hydraulic system’s needs determine the type of sequencing valve usage.

  3. Counterbalance Valves

Hydraulic counterbalance valves hold loads in place and control movement in hydraulic systems. They are mostly used in cranes and other heavy machinery where a load needs to be supported against gravity.

A counterbalance valve’s primary function is to keep a certain pressure in the hydraulic system, thereby preventing the load from falling due to gravity. It is accomplished by controlling the flow of hydraulic fluid between the reservoir and the actuator, which could be a cylinder.

Counterbalance valves are commonly fitted between the hydraulic system’s actuator and the directional control valve. They operate by sensing the pressure on the valve’s outlet side and adjusting the fluid flow appropriately.

The valve will close to stop fluid from returning to the reservoir, and the load will be maintained in place if it tries to move in the direction of gravity.

Both internally and externally piloted counterbalance valves are available. Internally piloted valves are automated and do not need an outside source of pressure, in contrast to externally piloted valves, which do.

In general, counterbalance valves are a crucial part of hydraulic systems that ensure large machinery’s effective and safe functioning.

  4. Pressure Reducing Valves

A pressure reduction valve is a kind of valve that is utilized in a system to control and lower the pressure of a liquid or gas. These valves are frequently seen in industries, plumbing systems, and cooling and heating equipment.

The pressure of the gas or fluid as it passes through the valve is automatically adjusted by the PRV. If the pressure on the valve’s upstream side becomes too high, the valve will remain slightly open, enabling some of the fluid or gas to pass and drop the pressure.

If the pressure on the upstream face is too low, the valve will be slightly closed to restrict the flow while maintaining the proper pressure.

Pressure-reducing valves are essential in many operations because excessive pressure can damage equipment and endanger employees. These valves verify that the system works safely and effectively by regulating and lowering pressure.

Precautions

Before installation of pressure control valves, you must take the following precautions.

• Adjusting a Pressure Control Valve

The piston and spring open and close the pressure control valve. The spring force may be adjusted to alter the opening and closing speed of the valve. More than one piston is employed to achieve the modifications, and diaphragms are used in some circumstances.

• Installing a Pressure Control Valve

When purchasing a pressure control valve, we must ensure that all protective plugs and packing are present. Confirm that all connections and plugs are removed before installing. Also, check the sealing that secures the valve setting is intact. We have to make sure the nameplate and identifying tags are accurate.

Conclusion

Henceforth, I have explained the pressure control valve well and how it works. In this article, I have discussed four major types of pressure control valves along with their applications. Read out this complete guide to know how you can install these valves and the precautions to follow.