When charging a standpipe from the pump, which valve operation helps avoid surge pressures?

When charging a standpipe from the pump, which valve operation helps avoid surge pressures?

• A. Open the valve gradually
• B. Open the valve fully and quickly
• C. Leave the valve closed until pressure rises
• D. Open the standpipe cap first

Answer: (D)

When charging a standpipe from the pump, the pipe system often contains trapped air. If you push water in without venting that air, the air gets compressed and you can get a sudden surge pressure, or water hammer, which can damage equipment and create unsafe conditions. Opening the standpipe cap first gives the trapped air a vent path so it can escape as water begins to flow. With the air vented, the fill proceeds more smoothly and surge pressures are minimized. After the cap is opened and air is expelled, you can continue with proper valve operation to control the remaining fill, but venting first is the key step to prevent a sudden pressure spike.

When charging a standpipe from the pump, the pipe system often contains trapped air. If you push water in without venting that air, the air gets compressed and you can get a sudden surge pressure, or water hammer, which can damage equipment and create unsafe conditions. Opening the standpipe cap first gives the trapped air a vent path so it can escape as water begins to flow. With the air vented, the fill proceeds more smoothly and surge pressures are minimized. After the cap is opened and air is expelled, you can continue with proper valve operation to control the remaining fill, but venting first is the key step to prevent a sudden pressure spike.