A pressure reducing valve is necessary when system pressures exceed what level?

A pressure reducing valve is essential in plumbing systems when the pressure exceeds a certain threshold to prevent potential damage to fixtures, appliances, and pipes. In this context, the correct answer indicates that a pressure reducing valve is necessary when system pressures reach 550 kPa or 80 psi.

When pressure in a plumbing system exceeds these levels, it can lead to issues like water hammer, leaks, and even rupture of pipes. The pressure reducing valve helps maintain a safe operating pressure, ensuring that the entire system functions efficiently and prolonging the lifespan of plumbing components.

This specified threshold of 550 kPa or 80 psi is particularly important as many residential fixtures and appliances are designed to operate effectively within this pressure range. Limiting the pressure to this level helps ensure comfortable water flow without the risks associated with excessively high pressure.

By contrast, the other options present higher pressure limits that may not align with the optimal operating pressures required for typical plumbing systems, leading to unnecessary complications. Understanding these pressure levels is crucial for maintaining a safe and effective plumbing system.