Check out this on the following Qld Trasnport web page:
www.qld.gov.au/emergency/safety/home/gas/gas-fuelled-engines

Gas fuelled engines
A gas fuelled engine is a type of gas system that supplies gas as a fuel to an engine. Other gas systems can be installed in a vehicle, trailer or boat, for example, a gas cooker or fridge in a caravan, mobile home, food van or boat.Any installation or repair work on a gas system in a vehicle, trailer or boat must be undertaken by an authorised company or person.On completion of a conversion/installation of a gas system, the installer must give you a vehicle/vessel inspection certificate. This certificate certifies that the installation complies with the relevant legislation and meets all safety requirements.It is very important that you get this certificate and retain it for your records.In addition, a gas system compliance plate needs to be fitted to all gas systems in vehicles, trailers and boats. This compliance plate certifies that the gas system is safe to use and complies with the relevant standards.

Marekkn said..
I thought it only applies to the LPG Vehicles (means powered by LPG) not the ones have LPG stove, thanks! :)