Frequently Asked Questions (FAQs) about Relief Valves
What are relief valves used for in industrial refrigeration systems?
Relief valves are critical safety devices that protect refrigeration equipment from dangerous over-pressure conditions. In industrial refrigeration systems, properly sized and installed relief valves automatically release excess pressure before it can damage vessels, piping, or components, helping to prevent catastrophic failures while ensuring compliance with safety codes and regulations.
What types of relief valves do you offer?
Our inventory includes dual relief valve assemblies, single relief valves, and cartridge-style replacements like Parker's "CRT KT" series. We stock Hansen's complete line of pressure relief devices, Danfoss safety relief solutions, and Parker's comprehensive cartridge kits in pressure settings from 150 PSIG to 400 PSIG to match various system requirements and applications.
How do I select the correct pressure setting for a relief valve?
Relief valves should be set at or below the maximum allowable working pressure (MAWP) of the vessel or component they protect, typically 25% above normal operating pressure. For standard industrial ammonia systems, common settings include 150 PSIG for low-side protection, 250-300 PSIG for high-side components, and 350-400 PSIG for high-temperature applications or discharge lines.
What's the difference between Parker's CSR and CSRH series relief valve cartridges?
Parker's CSR series (like "CRT KT,CSR4 300PSIG") are standard relief valve cartridges, while the CSRH series (such as "CRT KT,CSRH5 250PSIG") are designed specifically for high-capacity applications requiring greater flow capacity. The number in the model (1-5) indicates the size and flow capacity, with higher numbers providing greater relief capacity for larger systems.
How often should relief valves be replaced?
Most refrigeration safety codes and insurance requirements mandate relief valve replacement every five years, regardless of condition. Some jurisdictions may require more frequent replacement in certain applications. Regular testing and inspection should be performed annually, but even valves that test properly must be replaced according to the established schedule to ensure reliable operation.
Can relief valve cartridges be interchanged between manufacturers?
Relief valve cartridges are generally not interchangeable between different manufacturers. Parker cartridges like "CRT KT,CSRH3 150PSIG" are designed specifically for Parker valve bodies, while Hansen and Danfoss each have their own proprietary designs. When replacing cartridges, it's essential to match both the manufacturer and the specific model to ensure proper fit and function.
What is the purpose of dual relief valve assemblies?
Dual relief valve assemblies allow for one valve to be serviced or replaced while maintaining pressure protection through the second valve. These assemblies typically include a three-way valve that directs system pressure to both relief valves during normal operation but can isolate one valve for maintenance while keeping the other in service, ensuring continuous protection and compliance with safety regulations.
How do I determine the required relief capacity for my system?
Relief capacity requirements are determined by factors including vessel size, system charge, heat input potential, and applicable safety codes. Generally, vessels must have relief capacity sufficient to prevent pressure from rising more than 10% above the valve's set pressure during a fire or other emergency condition. Detailed calculations based on vessel surface area and other factors are required for proper sizing.
What maintenance is required for relief valves?
Regular visual inspection for corrosion or damage, verification of proper installation and discharge piping, and testing of valve operation are essential maintenance practices. While relief valves themselves should not be disassembled in the field, the complete valve or cartridge should be replaced according to the mandated schedule, typically every five years.
Do relief valves require special discharge piping considerations?
Yes, relief valve discharge piping must be properly sized to prevent excessive back pressure, adequately supported to handle reaction forces during discharge, and directed to a safe location. The discharge piping should be designed in accordance with applicable codes and should never have isolation valves that could prevent proper relief valve operation in an emergency.
