Found this here: http://www.austlii.edu.au/au/legis/qld/ ... sr2004479/
-- SAFETY REQUIREMENTS FOR TRANSPORTING CYLINDERS IN VEHICLES 1 Meaning of enclosed vehicle
(1) For this schedule, enclosed vehicle means any enclosed vehicle, whether or not--
(a) the vehicle is used for private or business purposes or is used for providing public transport; and
(b) 1 or more of the vehicle's windows are open.
(2) However, a vehicle to which the Transport Operations (Road Use Management) Act 1995, chapter 5A, applies, is not an enclosed vehicle.
2 Application of pt 2
This part applies in relation to cylinders for LPG.
3 Prohibition on carrying 30 litre cylinders in enclosed vehicles
A person must not carry a cylinder with a capacity of more than 30l in an enclosed vehicle.
Example of a cylinder that could not be carried in an enclosed vehicle--
a 13.5kg cylinder
4 Restriction on carrying 9kg cylinders in enclosed vehicles
(1) A person may carry a cylinder with a capacity of 8.5kg or more, but no more than 9kg, in an enclosed vehicle only for transporting the cylinder to or from a place where the cylinder is or was exchanged or filled.
(2) However, subsection (1) does not apply if the cylinder is transported in the vehicle in a sealed compartment that is vented to outside the vehicle.
5 No more than 2 cylinders may be carried at a time
A person must not carry more than 2 cylinders in an enclosed vehicle at a time.
6 Requirements for transporting cylinders in enclosed vehicles
A person who carries a cylinder in an enclosed vehicle must ensure--
(a) the cylinder is stored--
(i) securely in an upright position, in the boot of the vehicle if possible; and
(ii) in a way that avoids excessive exposure of the cylinder to heat or direct exposure to sunlight; and
(b) the service valve of the cylinder is tightly closed.