At Cannon Water Technology, we provide pressure relief valves from industry leading brands, such as Walchem and Icon Process Controls. These valves offer the exceptional combination of performance, robustness, and compatibility with various types of chemicals. Browse our collection to find the best pressure relief valve for your application.
Working of Pressure Relief Valves Explained
A pressure relief valve comprises three functional elements – a valve element, a sensing element, and a reference force element. Here, a spring-loaded poppet valve serves as a valve element, piston or diaphragm as a sensing element, and spring as a reference. When in operation, the upstream pressure and the spring employ opposing forces on the valve. If the force of the upstream pressure is larger than the spring force, then the poppet valve moves away from the valve seat enabling fluid to flow through the outlet port. The valve closes automatically when the upstream pressure drops below the set point.
Piston-style elements are more commonly used in applications where high relief pressures are a concern or where the relief pressure doesn’t require tight tolerances. Piston style elements receive friction from the piston seal which makes them sluggish. However, diaphragm style elements are preferred in applications where low-pressure conditions exist. They help reduce the friction observed in piston style elements.
Mechanical spring acts as a reference force element here. It exerts a force on the sensing element, a piston or a diaphragm, and closes the valve. Our pressure relief valves allow the users to adjust the set point of relief pressure by changing the force on the reference spring.
Tips to Choose the Right Pressure Relief Valve for Your Application
Choosing the right pressure release valve is important for ensuring the safety of your application, efficiency, and compliance with regulations. Our experts will work closely with you to understand your requirements before offering the right solution. However, the following pointers will be helpful if you are considering these valves for your application.
- Address the Application Requirements: Are you looking for boiler pressure relief valves? Or do you want pressure relief valves for gas or liquid services? Remember, the pressure relief requirements vary across applications.
- Address the System Parameters: You need to address a broad range of system parameters when buying the pressure relief valve for your application.
- Operating Pressure: Address the maximum and minimum operating pressure of your system. The relief valve must have a higher set pressure than the system; but it should be lower than the maximum allowable pressure of the system.
- Flow Rate: This factor would help you understand the relieving capacity of the valve. Ensure the valve can handle the maximum flow rate generated by the system.
- Choose the Right Type of Valve: Based on their designs, pressure relief valves can be distinguished into three types – spring-loaded, pilot-operated, and weight-loaded. These designs also contribute to their efficiency in certain applications. For instance:
- Spring-Loaded Pressure Relief Valves: These valves are equipped with a spring that contributes to their opening and closing. Spring-loaded pressure relief valves have simpler designs, which make them ideal for small systems where precise pressure control may be required. Most boiler pressure relief valves are of this type.
- Pilot-Operated Pressure Relief Valves: The system pressure serves as a pilot for opening and closing the valve. Pilot-operated pressure relief valves are suited for complex systems where high capacities and precise control over the opening pressures are required. These pressure relief valves are ideal for large chemical plants, oil and gas processing facilities, and power generation facilities.
- Weight-loaded Pressure Relief Valves: These valves use weights to close the valves, thus, the name. These valves are considered ideal for applications where the operating pressures remain stable, such as liquid storage tanks for storing chemicals and fuels.
- Regulatory Compliance: Ensure that the selected relief valve complies with relevant industry standards, codes, and regulations, such as ASME, API, or ISO standards. Compliance ensures that the valve meets safety and performance requirements for your application.
- Fluid Compatibility: Check the compatibility of the valve and the fluid. Ensure that the valve materials are compatible with the properties of the liquid, including its corrosiveness, viscosity, and chemical composition. For instance, brass or stainless steel are the most suited materials for valves, as they are compatible with various types of temperatures and chemicals.
- Size Appropriately: Choosing a valve of the right size is important to ensure the safety of your application. This is because an oversized valve can lead to premature opening or instability of the system. However, an undersized valve may not adequately protect your system. This sizing can be decided on the factors, such as system pressure, flow rate, and temperature.
- Consider the Discharge System: Address how the valve will discharge the pressure. For instance, it may open the air or the containment system.
- Maintenance and Testing: When buying a pressure release valve, you must also address its maintenance requirements. Always ensure that you invest in a pressure relief device that requires minimum maintenance.
How Does a Pressure Relief Valve Helps Prevent Overpressure Situations?
Pressure relief valves help prevent overpressure situations in boilers, pressure vessels, and containers. This overpressure may occur due to factors, such as external fire, flow from a high-pressure source, heat input from an external source, failure of the control systems, liquid expansions in pipes, chemical reactions, operational errors, the entrance of volatile fluid, and so on. If not prevented on time, this pressure may lead to equipment damage, catastrophic accidents, and operational disruptions. This is where pressure relief valves may help.
- These relief valves are designed to monitor the pressure in the system where they are used. In short, these valves are designed to the system’s internal pressure.
- Each valve is set to open at a predetermined pressure level, which is the set pressure. This set pressure is kept slightly above the system's normal operating pressure but is kept below the pressure at which the equipment or container may get damaged.
- When the valve opens, the excess pressure will escape in the form of liquid, expelling gas, or steam into a containment area or the environment.
- By venting the excess pressure, the pressure relief valves help maintain the system's integrity and ensure safe operation.
- When the system pressure falls below the set pressure, the valve automatically closes, which prevents the unnecessary loss of media from the system and allows it to return to regular operation. This is why pressure relief valves are a critical part of safety protocols and are often mandated by industry standards and regulations.
- They are designed to operate reliably under various conditions, ensuring the safety of both the equipment and the personnel.
Frequently Asked Questions on Pressure Relief Devices
- How frequently should pressure relief valves undergo maintenance and testing?
Pressure relief valves need to be frequently checked and maintained in compliance with industry guidelines and legal regulations. This involves constantly inspecting for wear and damage, testing for good operation regularly, and cleaning or replacing parts as necessary. This testing frequency would depend on the type of valve, its operating conditions, and so on.
- What are the signs of a malfunctioning pressure relief valve?
There are several signs of a malfunctioning pressure relief valve, such as continuous leaking or dripping, not reseating properly after activation, and no opening at the set pressure.
- What is the correct orientation for mounting a pressure relief valve?
It is always recommended to install a pressure relief device vertically because the valve body is self-draining; the valve is installed to the code; the correct set pressure and seat tightness can be achieved.
- What care should be taken to ensure the valve isn’t damaged during installation?
Although our valves are designed to meet the demands of challenging work environments, we still recommend users take extra care at the time of installation. If you are working with lightweight and small valves, be careful to handle them with care because these parts may get damaged due to accidental falls or mistakes made during the installation. If you are working with heavier valves, be careful about the lever. This is because the lifting straps would accidentally wrap around or otherwise conflict with it.
- Do you recommend painting these pressure relief valves?
We do not recommend painting on these valves, as they would conceal many internal or working parts.