Safety Relief Valves
Safety relief valves play a crucial role in safeguarding pressurised equipment or systems against overpressure situations. When pressure escalates beyond the capacity that the equipment or piping system these valves help avert potential severe damage to the system, as well as to the surrounding infrastructure and personnel.
Safety & Relief Valve Range
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Pressure Safety & Relief Valves
Safety relief valves are vital components in the management of pressurised systems, serving as critical safeguards against the dangers of overpressure. These devices are ingeniously designed to respond automatically when the pressure within a system exceeds predetermined safety limits, thereby averting potential catastrophic failures.
Their role is crucial in a wide range of industrial applications, from chemical processing to power generation, ensuring the protection of equipment, infrastructure, and personnel.
By maintaining operational integrity and safety standards, pressure relief devices not only prevent costly damages but also uphold the highest levels of safety in challenging industrial environments.
- Bronze safety and relief valves
- Stainless steel safety and relief valves
- Cast steel safety and relief valves
John Valves is also the Australian Stockist of Bailey Valves.
Safety Relief Valves Technical Sheets
Our commitment to industry to supply quality pressure Safety Relief Valves, we have made these technical sheets available. If you need further information please make a technical enquiry.
- Fig 68 Bronze Relief Valve
- Fig 723 Air Relief Valve
- Fig 848 Safety Valve
- Fig 848SS Safety Valve
- Update Coming Soon, Please Enquire
Excellence in the Safety Relief Valve Design & Engineering
Excellence in the design and engineering of pressure safety relief valves is paramount. Reflecting a harmonious blend of precision, innovation, and robustness. These valves are meticulously engineered to meet stringent safety standards, ensuring reliable performance under extreme conditions.
Advanced materials and cutting-edge manufacturing techniques contribute to their durability and efficacy. The design process involves a deep understanding of fluid dynamics, pressure control mechanisms, and material science, allowing optimal functionality tailored to specific industry needs. Moreover, continuous technological advancements, such as digital simulations and rigorous testing protocols, further enhance the precision and reliability of these critical safety components.
This dedication to excellence elevates the safety standards in various industries and instils confidence in the systems that rely on these pressure relief device.
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Operating Mechanisms
The operating mechanisms of safety relief valves are ingeniously designed for precision and reliability. At the core of their function is the ability to respond to changes in system pressure. These valves typically consist of a valve body, a seat, and a closing mechanism, often a spring-loaded disc or piston.
In normal operating conditions, the spring force keeps the valve closed. However, when the pressure within the system exceeds the predetermined threshold, the force exerted by the pressurized fluid or gas overcomes the spring tension, causing the valve to open. This opening allows the excess pressure to be safely vented or discharged, protecting the system from overpressure scenarios.
Once the pressure drops back to a safe level, the spring force reseats the valve, restoring the system to its normal state. This self-acting mechanism is crucial for ensuring the safety and stability of various industrial and mechanical systems, functioning autonomously to prevent potential hazards.
Safety Standards
In Australia, safety relief valves must comply with specific standards to ensure safety and reliability in various industrial applications. The primary standard governing these valves’ design, construction, and testing is AS 1271. This standard applies specifically to safety valves, other valves, liquid level gauges, and other fittings used on boilers and unfired pressure vessels, along with their associated piping.
Australian standards for safety valves are in line with international norms. For example, SAA AS1271 is mentioned alongside other international safety valve standards, demonstrating its relevance and alignment with global safety practices.
For detailed information on these standards and their specific requirements, it’s advisable to refer to the official documents or consult with industry experts. These standards are essential for anyone involved in designing, manufacturing, or maintaining safety relief valves and related pressure equipment in Australia.
Advantages of Pressure Relief Devices
- Overpressure Protection
Their primary function is to protect equipment, piping systems, and entire facilities from the dangers of overpressure, which can lead to equipment failure, explosions, or other catastrophic events. - Automatic Operation
Safety relief valves operate automatically, responding immediately to changes in pressure. This autonomous response ensures safety without requiring manual intervention, which is crucial in emergencies. - Prevention of Equipment Damage
By relieving excessive pressure, these valves prevent stress and potential damage to tanks, boilers, and other pressurised systems, thereby extending the lifespan of the equipment. - Compliance with Safety Standards
They help facilities comply with various safety regulations and standards, which mandate using such devices in many pressurized systems to ensure worker and environmental safety.
- Customisable Design
Safety relief valves can be designed and manufactured to meet specific operational requirements, including different sizes, materials, pressure settings, and discharge capacities, making them versatile for various applications. - Cost-Effective Safety Solution
While crucial for safety, these valves are generally cost-effective system components, especially when considering the potential cost of system failure or accidents due to overpressure. - Minimisation of Downtime
By preventing overpressure accidents, safety relief valves minimize unplanned downtime, which can be costly in repairs and lost productivity. - Environmental Protection
In industries where toxic or hazardous materials are handled, safety relief valves play a crucial role in preventing the release of these materials into the environment, thus safeguarding ecological health.
Industry Uses
Safety relief valves have a broad range of applications across various industries due to their critical role in maintaining safety and operational integrity in systems that operate under pressure. Some of the key industries that heavily rely on these valves include:
Water Supply Systems
Such as autoclaves and pressure leach systems, use safety and relief valves to prevent overpressure scenarios.
Oil & Gas Industry
To protect equipment from overpressure conditions due to process upsets, fire exposure, or equipment failure. For controlling the release of gases and liquids, preventing blowouts and equipment damage.
Power Generation
Safety valves are critical in steam systems to release excess steam to prevent explosions. To relieve excess pressure in case of turbine trip or shutdown.
Pharmaceuticals
In the pharmaceutical industry, where precise pressure control is essential for maintaining product integrity and safety, these valves are used in reactors, autoclaves, and other pressurised equipment.
Food & Beverage
Such as autoclaves and cookers, where safety valves prevent overpressure during processing. Relief valves maintain safe pressure levels in tanks and vessels.
Pulp and Paper Industry
In the manufacturing of pulp and paper, safety relief valves are employed in digesters, boilers, and other high-pressure systems to prevent overpressure conditions.
Water & Wastewater
To prevent overpressure conditions that can damage pipelines, pumps, and other components. Relief valves are used to prevent tanks from over-pressurising due to thermal expansion or gas generation.
HVAC Systems
Protect against overpressure caused by compressor failure or excessive heat. Safety valves in boilers and water heaters prevent overpressure from steam or hot water expansion.
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What is the difference between a pressure relief and safety valves?
The pressure relief valve (PRV) could also be referred to as a pressure safety valve (PSV). The naming of this device depends on there application. Both valves are used to protect the system and its components from overpressure, but they have different opening and closing characteristics.
Pressure Relief Valve
- A pressure relief valve opens gradually as the system pressure increases and closes gradually as the system pressure decreases.
- It can operate continuously or intermittently to regulate the pressure within a specific range.
- Used when the liquid is there in the system
- Discharge back to the system at lower pressure.
Pressure Safety Valve
- A pressure safety valve opens suddenly when the system pressure reaches the set point and closes suddenly when the system pressure drops below the set point.
- It operates only in emergency situations to prevent the pressure from reaching dangerous levels.
- Used where gas, vapor and steam are there in system
- Discharge to atmosphere
How often should safety relief valves be tested or maintained?
The frequency of testing and maintenance depends on the manufacturer’s recommendations and industry regulations, but it’s generally advised to perform checks at least annually to ensure they are functioning correctly and safely.
Can a safety relief valve be reused after it has opened?
It depends on the valve design and the severity of the overpressure event. Some valves are designed for multiple uses, while others may require inspection or replacement after activation.
How do you size a safety relief valve?
Sizing a safety relief valve involves calculating the required flow capacity to relieve pressure effectively without over-sizing, which can be as detrimental as under-sizing. This calculation typically considers factors like the type of fluid, system design pressure, and temperature.
What causes a safety relief valve to leak or fail?
Common causes of leakage or failure include improper installation, incorrect sizing, accumulation of debris, corrosion, and spring fatigue. Regular maintenance and inspection can help identify and mitigate these issues.
Can safety relief valves be adjusted or set in the field?
Generally, safety relief valves should not be adjusted after leaving the factory, as they are preset to specific pressure settings. Any field adjustments can compromise the system’s safety and may violate regulations.
Are there different types of safety relief valves for different applications?
Yes, there are various types of safety relief valves designed for specific applications, considering factors like the nature of the fluid (gas, vapor, or liquid), operating temperature, and pressure ranges.
How do backpressure and superimposed backpressure affect valve performance?
Backpressure (pressure downstream of the valve) can affect the opening pressure and capacity of a relief valve. Superimposed backpressure, present before the valve opens, can cause the valve to open prematurely or not at all if not accounted for in the design.
What are spring type safety/relief valve parts
Disc: This is the part that controls the flow of fluid through the valve. The valve element is usually held in the closed position by a spring force until the system pressure reaches the set pressure of the valve.
Adjusting Screw: This is the part that sets the system pressure and transmits it to the valve element.
Spring: This is the part that provides a reference force to balance the system pressure and keep the valve closed. The spring applies a force to the valve element.
Body: This is the part that contains and supports all the other parts of the valve. It also provides the inlet and outlet ports for the fluid to enter and exit the valve.
What is a Lifting Lever or Easing Gear?
The lifting lever allows you to lift the valve and flush the obstruction. Pressure relief valves for Section VIII require a lift lever on all air, steam, and hot water valves used at temperatures over 60 degC. Typically used where periodic testing of the valve in location is desired to assure its operation.
Standard safety valves are generally fitted with an easing lever, which enables the valve to be lifted manually in order to ensure that it is operational at pressures in excess of 75% of set pressure. This is usually done as part of routine safety checks, or during maintenance to prevent seizing.
Keep in mind, valves on thermal fluid heaters should NOT have a lever installed
