Which sequence is involved in properly operating the blowdown valves?

The correct sequence for operating the blowdown valves is to first open the outside valve and then close the inside valve. This method is essential for safe and effective operation.

When the outside valve is opened first, it allows for the flow of water or steam to exit the system, which helps in reducing pressure and clearing any sediment or impurities from the boiler or piping. By doing this before closing the inside valve, you ensure that there is no sudden pressure change that could cause water to surge back into the system or create a hazardous situation like backflow or water hammer.

Once the outside valve is open and the blowdown process is initiated, closing the inside valve ensures that the blowdown is contained, and it minimizes the risk of introducing contaminants back into the system. This two-step process not only promotes safety but also enhances the efficiency of blowdown operations, ensuring that the boiler remains in good working condition.

This sequence is generally accepted and standardized in power engineering practice to avoid complications that could arise from improper valve operation.