A turbine feedwater pump must be equipped with a ___ on the discharge line to protect the pump from excessive pressure.

A relief valve on the discharge line of a turbine feedwater pump is essential to ensure the pump operates safely within its specified pressure limits. The primary function of the relief valve is to automatically vent excess pressure that might build up in the system, thereby protecting the pump from potentially damaging conditions that can arise due to hydraulic surges, system blockages, or other abnormalities.

When the pressure in the discharge line exceeds a predetermined set point, the relief valve opens to allow some of the fluid to escape, which reduces the pressure and prevents the pump from experiencing conditions that could lead to failure or damage. This is particularly important in high-pressure systems, where the consequences of excessive pressure could be catastrophic, both for the pump and downstream equipment.

Other devices like pressure gauges, flow meters, and shut-off valves serve different purposes. A pressure gauge is useful for monitoring the pressure but does not automatically relieve it. A flow meter measures the rate of flow but has no protective function against pressure. A shut-off valve can isolate the pump but does not manage pressure during its operation. Thus, the relief valve is specifically designed for pressure protection, making it the correct choice for this application.