Standard for regulating valve fire protection
The control valve is the final control element that changes the process parameters such as medium flow, pressure, temperature, liquid level by means of power operation by accepting the control signal output by the adjustment control unit, also known as the control valve.
So far, there is still no single test or definition that can definitively determine whether a valve is fire rated. Many industrial societies, oil companies, insurance companies, valve manufacturers, and relevant agencies in the United Kingdom and the United States have stipulated various test methods. However, the type of valve under test and the main test specifications vary with the test method. The debate on combustion valve testing continues, and some attempts to combine two or more methods into a complete method are still inconclusive. How should we accurately define the fire valve? This is exactly the problem we want to study, first of all, we should study the problem of the soft seat standard of the valve.
Some people believe that metal gate valves and globe valves that do not melt in a fire are fire dampers. These valves are designed and constructed to ensure metal-to-metal contact before and after a fire, which prevents flammable fluids from entering the fire. However, when the metal valve seat is operated before fire, the sealing performance is not good. Due to the small amount of leakage, it is also allowed in most established fire protection standards.
Users require the valve to have both good sealing performance and fire resistance during normal operation. Many valve manufacturers have tried to solve this complex problem as early as 15 to 20 years ago. They have developed a variety of “soft” and “hard” sealing elements, all of which can maintain the metal surface after fire. contact seal.
Hard seats are made of metals or alloys that can withstand high temperatures themselves. The soft seat is made of rubber, plastic or elastic material with a melting point below 700°F (about 370°C). The soft seat can be burned after a fire, and then by the pressure of the system, the rotation of the valve plate, the spring force or the action of its own gravity Keep metal surfaces in contact. But many soft-seated valves are not ideal for post-combustion safety. If these resilient valve seats do not all burn out in a fire, no metal-to-metal contact can be made. The following table summarizes several combustion tests including soft valve seats. From the table, it can be seen that various test standards have different valve test specifications for analysis and comparison, and you can understand which five standards are more stringent. It must be pointed out that the American Petroleum Institute standard API 607 ”Flammability Test for Soft-Sealed Ball Valves (1977)” is a tentative standard that applies to all ball valves under 16 inches. Later, the second edition of the standard API RP6F was revised and the requirements were more stringent.
Valves provided by different manufacturers can only meet one or two of the fire protection standards described in the table below. For example, the fire-resistant plunger valves and ball valves provided by Rockwell Company can only meet API607 and API RP6F standards. , and the valves provided by other companies can only meet other standards.
The above has explained the fire protection standards for regulating valves, from the test methods and mechanisms that have not been completed at the beginning to the standards that have been gradually developed in the follow-up, which are the standards for fire protection of regulating valves described to you above. Before I shared with you “The Importance of Fire Control of Control Valves”, let’s take a look~