The operating differential pressure of a relief valve is the difference between its maximum:

The operating differential pressure of a relief valve refers specifically to the difference between its maximum operational capacity and the point at which it begins to open, known as the cracking pressure. The cracking pressure is the minimum pressure that must be exceeded for the valve to start relieving pressure. Thus, the operating differential pressure is a crucial performance metric because it indicates how much pressure is above the cracking pressure that the system can handle before the relief valve activates, ensuring safety and stability within hydraulic systems.

Understanding this concept is integral to hydraulic systems' operation, as it helps ensure that the pressure remains within safe limits, preventing potential hazards associated with overpressure conditions.