The A51H single-lever safety valve is a direct-acting safety valve utilizing the lever-and-weight principle. It amplifies the force of the weight through a single-lever system and transfers it to the valve disc to provide sealing force. When the system pressure acting on the force below the valve disc exceeds the mechanical force set by the lever and weight, the valve disc is lifted, allowing the medium to be released; after the pressure decreases, the weight force resets the valve disc to close. The "H" represents that the sealing surface is made of alloy steel. This valve has a simple and intuitive structure, with stable set pressure (determined by the position of the weight). It is a classic and reliable safety relief device used in traditional industrial fields for medium and low pressure, large displacement conditions. It was widely used in early industrial boilers, small power stations, low-pressure pressure vessels, compressed air storage tanks, and certain stationary steam power equipment. In modern industry, due to its large size, sensitivity to vibration, and relatively cumbersome adjustment of set pressure, it has been largely replaced by spring-loaded safety valves. However, it is still used in some specific traditional equipment or in applications with special requirements for explosion protection and maintenance-free.

A51H Single-Lever Safety Valve Product Diagram

1. Pilot-operated control, ensuring precise and reliable action

The opening and closing are controlled by an independent pilot valve (pulse valve), and the main valve itself does not have a spring to directly sense pressure. The action is smooth, without chatter, with an extremely small pressure difference during opening and closing, and excellent sealing performance, making it particularly suitable for systems sensitive to pressure fluctuations.

2. Large displacement, suitable for high pressure and large diameter applications

The main valve adopts a full-bore structure, featuring a large discharge area and exceptional discharge capacity. It is specifically designed for large-diameter pipelines above DN100 and high-pressure conditions (such as PN16-PN250), addressing the contradiction between large discharge capacity and structural strength.

3. Alloy steel hard seal (Type "H")

The sealing surface between the main valve disc and the valve seat is made of alloy steel (such as 13Cr) through build-up welding or integrally manufactured, featuring high hardness, wear resistance, and high temperature resistance, ensuring reliable sealing under high temperature and high pressure steam conditions.

4. High sealing performance, with extremely low leakage rate

Under normal operating pressure, the main valve disc is subjected to the combined action of an upward force from the system medium and a downward additional force provided by the pilot system, resulting in a significant sealing pressure ratio, which can achieve a tight seal with near-zero leakage.

5. With a sturdy structure, it maintains relative independence

The main valve body is thick, heavy, and sturdy, capable of withstanding high-pressure impacts. The pilot valve can be independently calibrated, repaired, or replaced without affecting the main valve body, ensuring convenient maintenance.