A pressure regulator cannot maintain its pressure once what occurs?

A pressure regulator is designed to maintain a specific output pressure level despite variations in upstream pressure and flow conditions. However, it has operational limits that can affect its performance.

When air begins to flow through the system, it introduces dynamic changes in pressure that the regulator must respond to. As flow demand increases, the regulator must adjust to maintain the preset output pressure. If the flow increases beyond the capacity of the regulator, it may not be able to compensate effectively, leading to a drop in the output pressure. This is particularly true if the regulator is sized improperly for the application or if flow characteristics exceed what it can regulate.

Therefore, the ability to maintain constant pressure is directly tied to the conditions of flow; once air starts flowing, it can effectively challenge the regulator's ability to maintain the desired pressure, especially as the demand fluctuates.