Hi, The Pressures Systems Safety Regulations state that they are concerned with: - Steam at any pressure. - Gases which exert a pressure in excess of 0.5 bar above atmospheric pressure. - Fluids which may be mixtures of liquids, gases and vapours where the gas or vapour phase may exert a pressure in excess of 0.5 bar above atmospheric pressure. With respect to the third item above, does anyone know if Ethylene Glycol pressurised to 800 bar falls under the above regulations? My initial thought was that it would due to the pressure being applied. However, having read the application of the above regulations I'm now uncertain. Apparently for a liquid to be considered a "relevant fluid" under the regulations the liquid must turn into a gas in the event of system failure, i.e. the gaseous element must separate out from the liquid to produce a vapour pressure in excess of 0.5 bar. Anyone with knowledge in this area that can advise? Thanks Rich

Rich I an intrigued to know what process you use Ethylene Glycol at over 11600PSI