(xxxix)"liquefied petroleum gas" means any material, which comprises predominantly of any of the following hydrocarbons or mixture of them with vapour pressure not exceeding 16.87 kg/cm2 (gauge) at 65° C; Propane (C3H8), propylene (C3H6), butane ((C4H10), (n-butane and iso-butane) and butylene (C4H8);
