Aux 1 Unit 4 Q1

Correct Answer: A) To prevent overloading the motor during startup

Explanation: Starting a centrifugal pump with the discharge valve closed or throttled minimizes the flow rate, reducing the power required to start the pump. This practice helps prevent overloading the motor during startup.

Correct Answer: B) To ensure proper ventilation to prevent the buildup of hydrogen gas, which could lead to an explosion

Explanation: Proper ventilation is essential in a battery compartment to prevent the buildup of hydrogen gas, a byproduct of the charging process. If not vented properly, this gas could accumulate and pose an explosion risk.

Correct Answer: D) The pump could overheat and possibly fail

Explanation: Leaving the delivery valve closed causes the pump to operate against a closed discharge, leading to overheating as the energy used by the pump has nowhere to go, which can eventually cause the pump to fail.

Correct Answer: B) It decreases power consumption

Explanation: When the discharge valve is closed or throttled, the pump experiences lower resistance and thus consumes less power during startup, making it easier for the motor to bring the pump up to operating speed.

Correct Answer: A) When the pump is used in a high-pressure, low-flow application

Explanation: In high-pressure, low-flow applications, a relief valve may be necessary to protect the system from the potential for pressure spikes, even with a centrifugal pump, which typically operates at lower pressures.

Correct Answer: B) The motor could be overloaded, leading to potential damage

Explanation: Starting with the discharge valve fully open could lead to an immediate high flow rate, which requires more power to handle. This can overload the motor, potentially causing damage to both the motor and the pump.

Correct Answer: B) A system with low-pressure requirements and large flow rates

Explanation: In systems where low pressure and large flow rates are required, the risk of excessive pressure build-up is minimal. Therefore, a relief valve is often unnecessary with centrifugal pumps, as they are not designed to handle high-pressure outputs.

Correct Answer: A) Centrifugal pumps are not capable of generating excessively high pressure

Explanation: Centrifugal pumps are designed such that their pressure output is limited by the system's characteristics. Unlike positive displacement pumps, they cannot generate pressures significantly higher than the design limit, making a relief valve less critical in some applications.

Correct Answer: B) It protects downstream components from sudden pressure surges

Explanation: Throttling the discharge valve during startup prevents sudden pressure surges that could damage downstream components, ensuring a more gradual buildup of pressure in the system

Correct Answer: B) It can cause excessive heat buildup within the pump

Explanation: If the delivery valve is left closed after the pump has started, the fluid within the pump will recirculate, causing friction and generating excessive heat. This heat can damage the pump, especially the impeller and seals.

Correct Answer: B) It will continue to circulate inside the pump, increasing in temperature

Explanation: With the delivery valve closed, the fluid inside the pump continues to circulate, leading to an increase in temperature due to friction and lack of flow. This can cause overheating and damage to the pump.