The British Compressed Gases Association (BCGA) has issued an updated revision of its Code of Practice 35 (COP35) – Filling ratios and developed pressures for liquefied compressed gases.

The Code of Practice offers updated information about the filling ratios that are applicable when filling gas cylinders with liquefiable gases for transport within the UK.


The document outlines that the liquid portion of the gas cannot occupy more than 97% of the total volume of the receptacle at the filling ratio reference temperature and that the receptacle cannot be liquid full at a temperature 5°C greater than the filling ratio reference temperature.

The revision does not apply to any international transport as in this case, the requirements of the European Agreement concerning the International Carriage of Dangerous Goods by Road (ADR) will apply. Therefore, the revision is only applicable to non Pi-marked cylinders.

The updated COP35 also gives information on the developed pressures in cylinders of compressed gas exposed to UK and other area climatic conditions, as the developed pressure is an important element in the establishment of the correct design criteria in some cylinder design codes.

It also explains that cylinders being exported from the UK may also need to be checked for safety per the climatic conditions they may be exposed to.