Propane is propane regardless of the grade. However, there are three grades of propane. Each of the three grades - HD5, HD10 and commercial propane differ in propane consistency and all have different purposes.
1. HD5 Propane known as consumer-grade propane. Made up of 90 percent propane , 5 percent propylene and 5 percent mixture of gases like butane and methane. It is the highest quality available and the only one that is recommended for use with vehicles such as forklifts, buses and certain taxis that have propane tanks.
2. HD10 Propane has the same makeup as HD5 with one exception. It permits 10 percent propylene within the propane/propylene mixture. It is not recommended for vehicle use. HD10 is perfectly suited for use in propane - powered appliances like a furnace or water heater.
3. Commercial Propane grade is often used interchangeably with HD10 because they both fall below the quality of HD5. However, commercial propane and HD10 propane often have different specifications for gas and propylene content and commercial grade only has to have enough propane to hold a flame. It is most common usage is for chemical processing in number of industries.