The Humphrey Quick Exhaust valve is versatile. Its most common function is to enhance the performance of air cylinders and air actuators with control of the exhausting air. Quick Exhaust senses pressure differential and redirects exhausting air to its third port. The third port can be left open, increasing cycling speeds and improving performance of the air cylinder. In other applications, the third port may be plugged for a check valve function, or restricted/metered for an excellent flow control function. Additionally, the Humphrey Quick Exhaust performs as an excellent shuttle valve function.