How many bottom blowdown valves are required on boilers operating at pressures above 100 psi?

For boilers operating at pressures above 100 psi, having two bottom blowdown valves is required for effective operational safety and maintenance. This dual-valve system serves a critical function in managing boiler water quality and pressure.

The first valve is used for the normal blowdown procedure, which helps remove sediment and impurities that accumulate at the bottom of the boiler. By regularly discharging a small quantity of water, this valve maintains the chemical quality of the boiler water, which is essential for preventing scale and corrosion within the boiler.

The second valve functions as a safety measure, allowing for the ability to isolate the blowdown system if maintenance or repairs need to be performed on the primary valve or if any issues arise. This redundancy ensures that there is always a means to manage the build-up of sediment safely, regardless of the operational status of the primary valve.

Together, these two valves provide a more comprehensive approach to boiler management at higher pressures, ensuring both operational efficiency and safety. In lower pressure systems, a single valve may suffice, but the increased risk and operational requirements of high-pressure boilers necessitate the additional valve.