Which of the following is the only type of pump that can be operated against a closed valve?

Which of the following is the only type of pump that can be operated against a closed valve?

• A. Diaphragm pump
• B. Submersible pump
• C. Centrifugal pump
• D. Positive displacement pump

Answer: (D)

A positive displacement pump is the only type of pump that can be operated against a closed valve because it works on the principle of trapping a fixed amount of fluid and forcing it through the discharge pipe regardless of the pressure in the system. This means that even if the valve is closed, the positive displacement pump will continue to generate pressure, allowing it to move fluid until the pressure becomes too high, potentially leading to damage. This characteristic is particularly useful in applications where consistent flow is required or when a system needs to maintain pressure. Other types of pumps, like centrifugal pumps, rely on the movement of fluid to create flow and would typically not be able to operate effectively against a closed valve, as they depend on liquid entering the pump for it to generate discharge. Similarly, diaphragm pumps and submersible pumps may have limitations when faced with a closed system, as they are generally designed to create flow and may not handle the back pressure created by a valve that is shut.

A positive displacement pump is the only type of pump that can be operated against a closed valve because it works on the principle of trapping a fixed amount of fluid and forcing it through the discharge pipe regardless of the pressure in the system. This means that even if the valve is closed, the positive displacement pump will continue to generate pressure, allowing it to move fluid until the pressure becomes too high, potentially leading to damage.

This characteristic is particularly useful in applications where consistent flow is required or when a system needs to maintain pressure. Other types of pumps, like centrifugal pumps, rely on the movement of fluid to create flow and would typically not be able to operate effectively against a closed valve, as they depend on liquid entering the pump for it to generate discharge. Similarly, diaphragm pumps and submersible pumps may have limitations when faced with a closed system, as they are generally designed to create flow and may not handle the back pressure created by a valve that is shut.