What type of valve must steam boilers be equipped with at the bottom?

Steam boilers are required to be equipped with a blowoff valve at the bottom primarily for the purpose of removing sediment and contaminants that accumulate over time. This helps to maintain the efficiency and safety of the boiler. The blowoff valve allows for the controlled release of water from the boiler, which brings out these impurities, thus preventing potential corrosion or damage to the system.

Regular use of the blowoff valve is essential for routine maintenance. By discharging a small amount of water, operators can ensure that the concentration of minerals and other deposits, which could lead to scaling, is kept at a minimum. This practice not only prolongs the life of the boiler but also helps in maintaining optimal performance.

While other types of valves play important roles in boiler systems, they serve different functions: for instance, a pressure relief valve is crucial for safety, as it prevents pressure from exceeding safe limits, and a drain valve is typically used for draining the entire boiler or system. The check valve, on the other hand, ensures that water flows in one direction but does not provide the sediment-removal capability that the blowoff valve does.