Commercial Propane is propane that has no regulated contents, but is generally assumed to be at least 80% propane, some propylene, butanes and ethane. HD-5 is defined as an LPG with a minimum of 90% propane, with a maximum of 5% propylene, and a minimum vapor pressure. The propylene is attributed to the formation of the sludgey compounds found in vaporizers. The missing part here is that HD-5 allows for a maximum of 5% of "other gases" which can be almost anything.
Note: This from the NPGA:
Propane HD 5 shall be a special propane for motor fuel and other uses requiring more restrictive specifications than Commercial Propane and shall conform to the following specifications:
VAPOR PRESSURES
The vapor pressure at 100°F as determined by NPGA LPG Vapor Pressure Test shall not be more than 200 pounds per square inch gage pressure.
95% BOILING POINT
The temperature at which 95% of volume of the product has evaporated shall be -37°F or lower when corrected to a barometric pressure of 760mm Hg., as determined by the NPGA Weathering Test for Liquefied Petroleum Gases
I am deeply involved with the Propane industry as is Graves Propane, and I would have to count on one hand with plenty of fingers left over any propane retail facilities who stock both HD-5 and Commercial propane. Generally, a dealer will buy the least expensive fuel that meets the needs of his customers, if they are residential heating they would use Commercial grade, if they are industrial or motorfuel forklifts or vehicles, they would typically use HD-5. In the US, there are no regulations mandating the sole use of HD-5, although there may be vehicle or fleet requirements or contracts with that stipulation.
Franz
Want more information on propane transfer pump? Click the link below to contact us.