Pressure Control Valves -The Ultimate Guide

Control valves are components typically incorporated into different systems and function as regulatory devices. There are a multitude of valves that function differently depending on the design. Their versatility is also applied to their various applications.

What is a Pressure Control Valve?

This is a control mechanism designed to regulate pressure in the systems they are installed in. These devices are typically incorporated into hydraulic systems whose operations are often sensitive to changes in pressure. They come in various configurations that are designed to perform specialized functions.

Why Install Pressure Control Valves

There are various reasons why installing pressure control valves is essential. These reasons include;

  • These valves are a means of prolonging the lifespan of the system by preventing high-pressure levels. Pressure levels outside of the recommended range can be damaging to various components in the systems.
  • Pressure control valves are a means of avoiding the potential bursting of the piper due to increased levels of pressure. When there are extreme levels of pressure in the system without a means of release the pipes can burst. This often results in added operational costs to replace damaged pipes.
  • The valves function as a safeguard against damage to the appliances caused by inconsistent pressure. The valves help to maintain levels which in turn protects the appliances used in these systems.
  • Maintaining optimal pressure will also in turn help conserve water as the correct amount required will be dispensed. This also helps to reduce utility costs due to conserved resources.
Functions of Pressure Control Valves

Functions of Pressure Control Valves

This valve performs a variety of functions in the system. These functions include;

  • The device is adapted to reduce pressure in the middle of various components smoothening operations.
  • Pressure control valves can be used to grip loads in a fixed position. This also ensures that there are no unconstrained movements within the system.
  • This mechanical apparatus can be used to provide sequential control. This function facilitates operations that are sequential and controlled.
  • It also functions as a limiting mechanism as it prevents pressure from building up past recommended settings. This helps safeguard the entire system preventing any possible damages.
  • The regulatory device functions as a means of controlling pressure in select areas of the system. It can apply sectional control isolating and regulating the pressure in the designated areas.
  • For applications that involve sequential operations, the versatile device can facilitate coordinated and accurate sequence movement control.
  • As an actuator sequence control these accessories effectively movement of the pressure-dependent actuator.
  • The valve plays a role in the unloading of pumps. The pumps are unloaded to deter the build-up of pressure which results in a significant strain within the system.

Where to Install Pressure Control Valves

Positioning of pressure control valves depends on several factors which differ according to the type of control valve you have. The area most suitable for installation can be determined by the design of the valve and its working principle. Depending on the configuration of your valve even the direction the valve faces may vary.

It is therefore important to first understand your control valve using the manufacturer’s guide. These guides often advise on the best location to install the control valve

Types of Valves for Controlling Pressure

For each valve, define the valve types, list features, benefits, limitations, and possible applications

Relief Valves

These are pressure-controlled valves whose main working principle hinges on their ability to react to high levels of pressure in the system by releasing it. When the system experiences elevated levels of pressure the valve opens relieving pressure which minimizes the risk of damage.

Features

  • It has a programmable cracking pressure which is the minimum allowable pressure in the system that will cause the valve will release.
  • The valve is adjustable to make it more efficient and is set to react once pressure levels reach their maximum limit.
  • It doubles as a safety measure ensuring that the system operates at safe levels of pressure at all times.

Types

  • Direct-operated pressure relief valves; this type of valve is an efficient and fast-acting design. This variation is directly triggered by real-time changes in pressure within the system. The design is better suited for applications that involve systems that experience moderate pressure.
  • Pilot-operated pressure relief valves; This variation of relief pressure valves is dependent on a pilot mechanism which is tasked with the responsibility of operating the valve. It offers a more precise and accurate response. The design is more advantageous when it comes to systems that experience high-pressure

Advantages

  • By releasing pressure these valves prevent any risk of injuries that may result due to strained systems.
  • There is a reduced risk of equipment getting damaged as a result of elevated pressure and safeguards against potential breakdown.
  • It is a method of constantly regulating the pressure to ensure that it is maintained at the recommended and safe levels.
  • They can be used for a long period without sacrificing the integrity of their performance
  • The valve can easily be maintained and is equally highly reliable.

Disadvantages

  • When releasing pressure from the system there can be a risk of also releasing hazardous materials.
  • Sudden release of pressure may have a damaging effect on pressure-sensitive equipment and components
  • These valves can also lead to leakages from the system when releasing pressure.

Applications

These valves can be used in the following

  • Boilers and pressure vessels
  • Hydraulic systems
  • Pneumatic systems
  • Oil and gas industry
  • Chemical and petrochemical industries
  • Water and wastewater systems
Relief Valve
Relief Valve

Reducing Valves

These pressure control valve functions minimize the pressure of substances that drift downwards through the device. This ensures that the lower end of the stream will constantly have lower pressure than the upper end of the stream. The mechanism is set in place to protect equipment and components operating downstream.

Advantages

  • This mechanical device is adapted to control pressure in the system and ensures that optimum levels are maintained.
  • These regulatory devices are highly adjustable and can be set to your desired pressure levels.
  • This mechanism helps protect your equipment that can potentially be damaged by elevated pressure in the system
  • The reducing valves are designed to be highly reliable when it comes to manipulating pressure levels in the system
  • It can also be installed as a safety precaution as it ensures that no equipment is damaged due to overpressure.

Disadvantages

  • These valves are vulnerable to wear and tear when regularly utilized. They often have to be replaced to maintain the system operations
  • Given that they serve as a barrier between two different pressure level sections they are prone to malfunctions. This could result in a spiking of pressure in the system that may damage sensitive equipment.
  • These control devices require regular maintenance to effectively function
  • This mechanical control mechanism is relatively more expensive to purchase as well as install

Applications

These valves can be utilized in the following areas

  • Water supply systems
  • HVAC systems
  • Pneumatic systems
  • Gas distribution networks
Reducing Valve
Reducing Valve

Unloading Valves

These valves operate by relieving pressure in a system to regulate pressure. They achieve this by redirecting excess pressure back into the reservoir. When pressure builds up in the system and exceeds its maximum level the valve opens allowing a backflow into the reservoir.

Advantages

They maintain the pressure in the system by off-loading excess liquid back into the reservoir. This ensures that the system keeps functioning under optimal conditions

Regulating pressure using this mechanism is a way of saving energy as it ensures that the load in the system is kept at a minimum. This in turn reduces the amount of power required for the system to effectively function.

They are designed to help reduce the heat in the system using a redirecting flow to a secondary pump. The recirculating oil will distribute the heat as it moves the redirected pathway.

This device can be controlled remotely which is not only convenient but allows the operator to carry out other duties and therefore has more flexibility.

Disadvantages

  • These valves require skill to operate because of their more complicated design.
  • Releasing the excess fluid back into the reservoir often results in a loss of energy in the system. You may need to install other supporting equipment to maintain smooth operations in the system.
  • This valve increases the risk of a leakage in the system
  • They are more expensive given their complex design. It also costs a lot more to regularly maintain them.
  • The valves require frequent maintenance to keep it functioning properly

Applications

It can be used in the following areas;

  • Hydraulic systems
  • Mobile equipment
  • Construction machinery
  • Power units
Unloading Valve
Unloading Valve

Counterbalance Valves

These mechanical devices are designed to keep loads in their designated areas thereby preventing uncontrolled movement within the system. The pressure generated by the load is impressed on an adjustable spring. Once the set pressure has been achieved the device releases the load allowing it to flow into the system before closing up once again.

Advantages

  • These regulatory devices help enforce the controlled movement of different loads within the system.
  • It is used as a safety feature as the device protects the equipment from damage resulting from load exertion.
  • With counterbalance valves, the system has a lot more flexibility as you can incorporate directional valves. These valves are ideal especially when space is a limiting factor given their small size.
  • Controlled movement of load while restricting smaller loads less strain is put on the system which helps conserve energy.
  • These valves are also very efficient when it comes to controlling the speed of loads moving through the system.

Disadvantages

  • These devices are not fail-safe and cannot ensure the safety of operators in the event that the valve releases its load quickly.
  • The device cannot prevent pressure spikes and may cause chattering causing irregular pressure that may be damaging to sensitive equipment.
  • It is not efficient when it comes to pressure control as adjustments are required depending on the settings. For example, systems with increased settings will need increased pressure to release the load
  • The device is complex and therefore costs more to purchase and maintain

Applications

These devices are utilized in the following areas;

  • Mobile equipment
  • Cranes
  • Industrial machinery
  • Hydraulic systems
Counterbalance Valve
Counterbalance Valve

Sequence Valve

This device relies on specified pressure levels and is operated using a primary circuit. The system is set with a specific pressure threshold beyond which the valve is opened and flow is directed to secondary systems. This creates an organized and sequential system where tasks are controlled and depend on the completion of one for the next task to be executed.

 sequence valve
Sequence Valve

Advantages

  • These valves are ideal for systems that require sequential operations. It allows for the occurrence of separated operations that are to be carried out in an already determined format.
  • They can also double as relief valves in systems that experience elevated levels of back pressure.
  • It allows you to regulate two operations that follow one another making it easier to operate the operations.
  • It helps to relieve pressure created by the load-protecting equipment that may get damaged due to strain on the system

Disadvantages

  • These valves create increased heat in the system making it unsuitable for heat-sensitive applications
  • There is an imbalanced pressure between the first actuator and the secondary one which received the diverted load.

Applications

Some of the uses of these valves include

  • Manufacturing process
  • Machine tools
  • Material handling equipment
  • Automated systems

Comparing Pressure Override and Cracking Pressure

Cracking pressure is essentially the minimum pressure that triggers the relief valve to open creating a passage for fluid to move through.

It is a vital parameter as it will determine the level of pressure allowed within the system. Once the specified level of pressure is obtained the valve mechanism will be released allowing fluid to pass through thereby relieving pressure.

Pressure override refers to the pressure difference between the cracking pressure and optimum flow pressure. This parameter is the total amount of increase in pressure once full flow has been achieved. Although it is not observed in all systems it provides valuable insight into the workings of the system and is a vital tool for monitoring operations.

Factors to Consider when Choosing Pressure Control Valves

Several factors should be taken into consideration when it comes to selecting the most suitable pressure control valves. These factors include

  • You should consider your intended application pressure and temperature requirements. Valves are designed using a variety of materials and configurations. The type of materials used will determine the amount of pressure and temperature the device can withstand.
  • The type of substance to be regulated by the mechanical device is also another important factor to consider. Various types of pressure control are adapted differently to regulate a limited range of substances. For example, only specific types of control valves are suited for corrosive materials.
  • Your application requirements can help you determine the best valve for you with regard to the valve’s features and functionality. The different working mechanisms are each adapted to different applications. You should therefore select one that will fit into your system’s intended use.
  • You should also take into account the set pressure for your system. This parameter will be used to control the operation of the valve as it determines the level at which the valve opens. The parameter is measured in pounds per square inch.
  • The back pressure experienced in your system will help determine the most suitable valve to be used. This pressure may also vary in some systems and may remain constant in others.
  • You should also select an appropriately sized valve that will handle your scale of operations. You should also factor in the coefficient flow

Precautions Before Installing Pressure Control Valves

Before initiating the installation process, you should take the following precautions

  • You should inspect the location where you intend to install the valve. The areas should be thoroughly cleaned both the inner cavity and the exterior.
  • Ensure that you obtain all the required information about the type of valve you have from the manufacturer guide if available. For more complex designs it is best to engage the services of an expert to ensure that the valves are properly installed.
  • Select the most appropriate and functional position for your valve. You factor in the working position as well risk of leakages when selecting the most appropriate position.
  • With some configuration of pressure valves, the direction of the valve will factor in the efficiency of the device. It is therefore important to understand how your valve functions and position it correctly to maximize efficiency.
  • When installing during construction additional care should be taken as force impacted on the valve may cause damage which will in turn interfere with the system if the damage goes unnoticed. It will also increase expenditure as a replacement valve will be required.

Conclusion

There are numerous types of pressure control valves designed with unique features and varying materials. It is therefore important that you consider your system requirements as well as the type of application when selecting the best valve for you.

More Resources:

Types of Hydraulic Cylinders – Source: Target Hydraulics

Types of Hydraulic Systems – Source: Target Hydraulics

Pressure Testing in Hydraulic Systems – Source: Target Hydraulics

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