What is a POL valve/fitting?
A POL (Prest-O-Lite) valve is a left-hand threaded connection point on propane cylinders and appliances that has been the US industry standard since the early 20th century. It differs from newer quick-connect fittings and requires a wrench to tighten or remove.
The POL valve, short for Prest-O-Lite, is the threaded connection found on most propane cylinders and many stationary appliances throughout Florida and the broader US market. Named after the Prest-O-Lite Company that developed it, this fitting has remained the standard connection type for over a century.
What sets the POL apart from other propane connections is its left-hand thread, which turns counterclockwise to loosen and clockwise to tighten. This reverse-thread design was intentional: it prevents accidental disconnection and is a safety feature that operators of propane equipment should always keep in mind. The valve itself typically includes a pressure relief valve and a shutoff mechanism integrated into the fitting.
POL fittings are found on portable propane tanks, forklift cylinders, grill bottles, and the regulator connections on many permanent outdoor appliances. Newer propane equipment and portable devices sometimes use quick-connect fittings instead, which allow tool-free attachment and disconnection. However, POL remains the dominant standard for refillable cylinders in the propane delivery industry, making it essential knowledge for Florida propane suppliers and end users alike.
The left-hand thread design requires a wrench for connection and disconnection, which contrasts with the hand-tight convenience of some modern alternatives. Understanding POL fittings is critical for safe handling, proper storage, and correct equipment hookup in propane operations.