Valve manufacturers usually state their pressure drop in terms of:

Valve manufacturers typically express their pressure drop in terms of a coefficient known as the CV rating. This rating quantifies the flow capacity of a valve, essentially indicating how much fluid can flow through the valve at a specified pressure drop. The CV value helps engineers and technicians assess the performance of a valve in various applications, as it directly relates to the effective flow area and resistance the valve offers to the fluid passing through it.

The CV rating allows for easier comparisons between different valves and their capabilities, making it a critical parameter in selecting the right valve for a particular system. By providing a standardized measure, it assists in designing efficient piping and fluid systems, ensuring that the selected valve will meet the flow requirements while minimizing pressure losses.

Other choices, such as pressure loss coefficient, flow rate, and fluid viscosity, while relevant in different contexts, do not serve the same purpose as the CV rating, which is specifically focused on flow capacity and pressure drop across the valve.