Which of the following systems is commonly used to ensure a minimum flow rate through a pump at a constant speed?

The minimum flow control valve system is designed to maintain a certain minimum flow rate through a pump, particularly when the pump is operating at a constant speed. This is crucial for the protection of the pump, as running a pump with insufficient flow can lead to overheating and damage due to inadequate cooling and lubrication.

In a typical setup, a minimum flow control valve is placed in the discharge line of the pump and is calibrated to open when the flow falls below a predetermined threshold. This allows some portion of the flow to be redirected back to the pump's suction side, ensuring that the pump always has enough liquid circulating through it, even when demand is low.

Maintaining the minimum flow is important for avoiding “dead head” situations, where the pump is generating pressure but not moving fluid adequately, which can result in excessive wear or failure. This type of system is often used in applications where the pump operates under variable demand conditions or has the potential to run at low flow rates.

Other choices, such as pressure relief valve systems, are primarily used to protect the system from excessive pressure, while pump speed control systems adjust the pump’s operation based on demand rather than ensuring a minimum flow. Flow rate indicators, on the other hand, are valuable for monitoring but do