What type of control valve allows for an infinite range of firing rates between low fire and high fire?

The type of control valve that allows for an infinite range of firing rates between low fire and high fire is known as a high cycle rated valve. These valves are designed to adjust the flow smoothly and continuously within a specific range, enabling precise control over the fuel or gas being supplied to a burner system. This capability is essential in applications where the demand for gas can fluctuate, allowing the burner to modulate its output efficiently instead of simply being either fully open or fully closed.

In contrast, on/off valves only provide two distinct states—fully open or fully closed—resulting in a lack of control over firing rates. Pressure relief valves serve a different function, primarily for safety by releasing excess pressure rather than regulating flow rates. Flow control valves, while they can modulate flow, typically do not provide the same level of precision in firing rate control as a high cycle rated valve, which is specifically intended for applications requiring seamless transitions between low and high flows. Hence, the high cycle rated valve is key for achieving the infinite range of firing rates necessary in these systems.