Propane, the main component in liquefied petroleum gas (LPG), is widely recognized as a clean-burning fuel for a variety of applications, including vehicles. However, propane hoses used to transfer propane are one source of fuel contamination because of extractable materials released when exposed to propane.
Most materials, including rubber, are porous at a microscopic level, allowing liquids and gases to pass through via permeation. The permeation rate in LPG hose is controlled by internal pressure and hose construction. If the permeation rate is high enough, it may trigger failures in the Sealed Housing for Evaporative Determination (SHED) test, part of evaporative emission control test protocol and regulations. The SHED test consists of operating a vehicle inside a sealed chamber for a specified time to detect the level of hydrocarbon emissions.
In response to these issues, PERC initiated a research effort, Conditioning LP Gas Hose Prior to Entering Service, to determine which contaminants are released from hose, the magnitude of contamination, and a method to treat hose prior to use that greatly reduce subsequent releases.
For a condensed look at the report’s findings, simply download the fact sheet here.