13.1.1 Where
                                 a liquid blowdown system is provided in the process plant, the design
                                 and installation are to make adequate provision for the effects of
                                 back pressure in the system and vapour flash off when the pressures
                                 of liquids in the blowdown system are reduced.
                              
                              
                              
                            
                           
                           
                           
                              
                              
                              13.1.2 Substances
                                 which will react with each other are to be provided with separate
                                 systems.