Advantages and Disadvantages of Pressure Relief Valves
In industry, to ensure the safety of pressure equipment, pressure relief valves are used.
You might be interested in understanding how these valves work and their components.
Next, we will learn about the operation of these valves, their types, advantages, and disadvantages.
What is a Pressure Relief Valve?
The simplest definition of pressure relief valves is that they automatically or manually reduce high and variable input pressure to a constant output pressure.
Function of Pressure Relief Valves
Whenever conditions arise that cause pressure in a system to increase to a dangerous level, a pressure relief valve can be the only device that prevents catastrophic failure.
Using various pressure relief valves by reducing unwanted pressures in the network will significantly prevent fluid and energy waste and can reduce many transmission costs.
Operation of Pressure Relief Valves
The operation of pressure relief valves is based on the action and reaction between two opposing forces.
The force generated by the fluid causes the flow path to close, and the opposing force from the spring tends to open the flow path.
Both forces act to neutralize each other, and due to the variable reactive property of the spring, which is designed to accommodate input changes, the output pressure remains stable.
Advantages and Disadvantages of Pressure Relief Valves
The advantages of pressure relief valves include:
- They have a very simple design and are low-cost.
- Maintenance of pressure relief valves is easy.
- They significantly reduce external leakage.
- No external force is needed for valve loading.
- Due to the absence of packing, external leakage and high friction sources are eliminated.
- They are suitable for liquids, gases, and vapors.
However, pressure relief valves also have disadvantages, such as:
- The control environment must be completely clean for proper operation.
- When the pressure drop in the valve is low, regulators lose control capability because the environment cannot provide sufficient operational power.
- Regulators do not adapt well to noise/cavitation.
Installation of Pressure Relief Valves
Before installation, open all valves in the system to completely evacuate air from the piping system. To facilitate maintenance, install two shut-off valves on both sides of the pressure relief valve.
- Ensure to install pressure relief valves according to the indicated direction.
- Pressure relief valves can be installed both horizontally and vertically.
- The desired output pressure can be adjusted by turning the upper spring screw of the pressure relief valve (clockwise to increase the output pressure and counterclockwise to decrease the output pressure).
Types of Pressure Relief Valves
The most important point in selecting pressure relief valves is to consider the application site and the fluid usage information. Based on this, pressure relief valves are categorized into two types based on their operation: direct-acting and pilot-operated.
Additionally, pressure relief valves are classified by the type of fluid flowing through them into two types: hydraulic and pneumatic.
Direct-Acting Pressure Relief Valve
In this model, a sensitive element for reducing pressure exists that directly operates the valve. This valve is simple, small, lightweight, and very efficient for controlling low flows.
Applications of Direct-Acting Pressure Relief Valves
Applications of this type of pressure relief valve include:
- Food industry
- Laundry equipment
- Steam sterilization systems
- Equipment using low-pressure air
Pilot-Operated Pressure Relief Valve
This type of valve reacts to pressure reduction due to its pilot and directly operates the valve. Consequently, the main valve is also controlled and operated by the pilot’s working pressure. Pilot-operated valves are recommended for maintaining high flow rates and control.
Hydraulic Pressure Relief Valve
In a hydraulic system, the pressure relief valve regulates the flow. This type of valve operates with a manual lever connected to the valve to control fluid flow. Hydraulic pressure relief valves are common and widely used in the industry.
Applications of Hydraulic Pressure Relief Valves
Hydraulic pressure relief valves are used in various industries, including:
- Cement industry
- Automotive industry
- Steel industry, and more
Pneumatic Pressure Relief Valve
This type of pressure relief valve operates by measuring the pressure of the flowing fluid with a sensor and sending it to the controller. Additional components such as actuators, positioners, and controllers enable these valves to create significant pressure drops.
Applications of Pneumatic Pressure Relief Valves
- Automotive industry
- Agriculture industry
- Wood industry
- Food industry
Source: namatek
