Propane Cylinder Valves

Propane valves are essential safety and control devices on propane tanks and lines that manage the flow, filling, and pressure of liquefied petroleum gas (LPG). They range from simple shutoff handles to complex internal components like Pressure Relief Valves (PRVs) and Overfill Prevention Devices (OPDs). 

Key Functions of Propane Valves:

> Shutoff: Allows you to manually turn the gas supply on or off.
> Pressure Relief: Pop-off valves (PRVs) release excess pressure to prevent tank rupture from heat or overfilling, often called "pop-off" valves.
> Excess Flow: Shuts off gas flow rapidly if there's a sudden leak or high demand, preventing dangerous rapid release.
> Filling/Vapor Service: Specific valves manage the process of filling the tank and drawing vapor (gas) for use. 

Common Types of Valves & Fittings:

POL (Prest-O-Lite) Valve: An older design with internal threads, requiring a wrench, found on older tanks.
ACME (Type 1) Valve: Newer, more common for grills, with external threads and a handwheel for easy connection and shutoff.
OPD (Overfill Prevention Device): A mandatory safety feature that stops tanks from being filled too full, often integrated into the main valve.
Regulator Valves: Reduce the high pressure from the tank to a safe, usable pressure for appliances.