Why two valves are provided on boiler blow down side?

Two valves are provided on the boiler blowdown side for safety and operational efficiency. The first valve is typically a blowdown valve that allows for the controlled release of water to remove impurities and sludge from the boiler. The second valve serves as a shut-off valve, ensuring that in case of maintenance or emergencies, the blowdown process can be safely halted without compromising the system's integrity. This two-valve arrangement helps prevent accidental discharge and provides redundancy for safe operation.