|More than 8 inch
Pilot-operated safety valves (POSVs) are important components used in various industries to protect equipment and systems from overpressure conditions. Here is some information about pilot-operated safety valves:
Function: Pilot-operated safety valves are designed to automatically relieve excessive pressure in a system to prevent catastrophic failures or damage. They act as a last line of defense against overpressure situations.
Principle of Operation: POSVs consist of two main components: the main valve and the pilot valve. The main valve is responsible for controlling the flow of fluid or gas, while the pilot valve senses the pressure and triggers the main valve to open or close based on a set pressure limit.
Pilot Valve: The pilot valve is connected to the main valve by a control line or pilot line. It is usually smaller in size and uses a pressure-sensing element, such as a diaphragm or piston, to detect the system pressure. When the pressure reaches a predetermined set point, the pilot valve opens, allowing the fluid or gas to flow through the main valve and be safely discharged.
Main Valve: The main valve is a larger valve that controls the flow of the process fluid or gas. When the pilot valve opens, it releases the pressure from the main valve actuator, causing it to open and relieve the excess pressure. Once the pressure drops below the set point, the pilot valve closes, and the main valve returns to its closed position.
Advantages: Pilot-operated safety valves offer several advantages over direct spring-loaded safety valves. They can handle higher pressure and flow rates, provide more accurate pressure control, and offer better stability in dynamic systems. They are also suitable for applications with high backpressure or high differential pressure.
Applications: Pilot-operated safety valves are commonly used in industries such as oil and gas, petrochemical, refining, power generation, and chemical processing. They are employed to protect equipment like pressure vessels, boilers, pipelines, storage tanks, and other critical systems.
Codes and Standards: POSVs must comply with relevant industry standards and codes, such as the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (BPVC), International Organization for Standardization (ISO) standards, and various national regulations.
Maintenance and Testing: Proper maintenance and periodic testing of pilot-operated safety valves are essential to ensure their reliable operation. This includes routine inspection, cleaning, and calibration of the pilot valve, main valve, and associated components.
Installation Considerations: POSVs should be installed as close as possible to the protected equipment or system to minimize pressure losses. The control line between the pilot valve and main valve should be properly sized and protected against potential blockages or leaks.
Safety Considerations: While pilot-operated safety valves play a crucial role in preventing overpressure incidents, they should not be relied upon as the sole safety measure. A comprehensive pressure relief system, including other protective devices like pressure relief valves and pressure transmitters, should be implemented to ensure overall safety.
It's important to consult industry-specific guidelines and engage with qualified professionals for specific requirements and recommendations regarding pilot-operated safety valves in your particular application.