What are the testing requirements for vehicles powered by LPG (Liquid Petroleum Gas) and how does it apply to "cars on gas Barry"?

For vehicles powered by LPG (Liquid Petroleum Gas), specific testing requirements differ from those of conventional gasoline or diesel engines. When conducting emissions testing on an LPG vehicle, it is crucial to adjust the hydrocarbon (HC) reading to accurately represent the emissions. This adjustment involves dividing the HC reading by a 'propane/hexane equivalency factor' (PEF) marked on the gas analyser. For instance, if the HC reading is 180 parts per million (ppm) and the PEF is 0.48, you would divide 180 by 0.48 to obtain the correct emissions value for the LPG engine. This unique calculation ensures that the test results accurately reflect the emissions characteristics of LPG vehicles, allowing for proper compliance with emission standards and regulations. Understanding this process is essential for anyone searching for information on "cars on gas Barry" or similar inquiries, as it highlights the specialized nature of testing for alternative fuel vehicles like those running on LPG.