Propane suppliers glossary

Short, plain-English definitions of the terms you'll meet when choosing a propane supplier provider in Florida.

What is a BTU (British thermal unit)?: A BTU is a unit of measurement for heat energy, used to specify the heating capacity of propane appliances and determine appropriate tank sizes.
What is a DOT cylinder?: A DOT cylinder is a portable propane tank that meets U.S. Department of Transportation safety and design standards for containing and transporting liquefied petroleum gas at pressure.
What is a leak test or pressure test?: A leak test (also called a pressure test) is a safety inspection that confirms propane tank connections and fuel lines are airtight after installation or repair work.
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.
What is a regulator (first stage/second stage)?: A regulator is a device that reduces propane pressure from a tank to the lower pressure required by appliances, available in single-stage, two-stage, or integral twin-stage configurations.
What is a tank gauge (percentage gauge)?: A tank gauge is a mechanical meter mounted on a stationary propane tank that displays the liquid level as a percentage, typically using a float-and-arm mechanism to show fill capacity.
What is a tank lease agreement?: A contractual arrangement where a propane supplier retains ownership of the storage tank and leases it to the customer for a recurring fee, typically with exclusivity and removal clauses.
What is an ASME tank?: An ASME tank is a stationary propane storage vessel of 120 gallons or larger that meets American Society of Mechanical Engineers pressure vessel codes and is designed for permanent outdoor installation at a property.
What is an OPD valve (overfill protection device)?: An overfill protection device (OPD) is a safety valve with a distinctive triangular handwheel required on all portable propane cylinders manufactured since 1998 to prevent overfilling and accidental liquid propane withdrawal.
What is autogas (propane vehicle fuel)?: Autogas is liquefied propane (HD-5 grade) stored under pressure in vehicle fuel tanks and burned in internal combustion engines as an alternative to gasoline or diesel.
What is cylinder recertification?: Cylinder recertification is the federally mandated requalification of a DOT propane cylinder after 12 years (or per the cylinder's stamped interval) through visual inspection and official restamping to verify safety and continued use.
What is degree day calculation?: Degree day calculation is a method that measures the difference between outdoor temperatures and a baseline (usually 65°F) to estimate heating fuel demand and inform propane delivery schedules.
What is gallon water capacity vs propane capacity?: Tank water capacity is the total volume a tank can hold if filled with water, while propane capacity refers to the actual amount of propane (about 80% of water capacity) safely stored inside to account for liquid expansion.
What is HD-5 propane grade?: HD-5 is a high-purity propane grade that meets ASTM D1835 specification for use as engine fuel in vehicles, forklifts, and fleet equipment, with stricter limits on sulfur and other contaminants than heating-grade propane.
What is keep-full delivery?: Keep-full delivery is an automatic propane service where the supplier monitors tank depletion using degree-day calculations and schedules refills to prevent runouts, eliminating the need for a tank gauge monitor.
What is LPG (liquefied petroleum gas)?: LPG is a mixture of propane and butane gases compressed into liquid form for easier storage and transport, commonly sold by fuel suppliers under pressure in tanks.
What is odor fade?: Odor fade is the gradual weakening or loss of the mercaptan scent added to propane, which reduces the gas's detectability in case of a leak.
What is propane odorant (ethyl mercaptan)?: Ethyl mercaptan is a chemical odorant added to propane to create a strong, distinctive smell, allowing people to detect leaks in naturally odorless propane gas.
What is propane vapor pressure?: Vapor pressure is the force exerted by propane gas molecules against the walls of a tank, which rises with temperature and determines whether gas can flow to appliances.
What is propane?: Propane is a flammable hydrocarbon gas produced as a byproduct of natural gas processing and crude oil refining, stored as a liquid under pressure in tanks for use as fuel.
What is the 80% fill rule?: The 80% fill rule is a federal safety requirement that propane tanks be filled to only 80% of their total capacity to allow for gas expansion without exceeding safe pressure limits.
What is vapor withdrawal vs liquid withdrawal?: Vapor withdrawal extracts propane gas from the top of a tank for typical residential appliances, while liquid withdrawal draws propane liquid from the tank bottom for high-demand commercial and industrial equipment requiring greater fuel volumes.
What is water column inches (WC)?: Water column inches (WC) is a unit of measurement for gas pressure in propane systems, where 1 inch of WC equals the pressure exerted by one inch of water in a vertical column.
What is will-call delivery?: Will-call delivery is a propane refill service model where the customer is responsible for monitoring their tank level and calling the supplier to schedule a delivery when propane runs low, rather than receiving automatic scheduled refills.