(5)Pressure reducing devices. - (a) Every pressure vessel which is designed for a working pressure less than the pressure at the source of supply or less than the pressure which can be obtained in the pipe connecting the pressure vessel with any other source of supply, shall be fitted with a suitable automatic device to prevent the minimum permissible working pressure of the pressure vessel being exceeded;(b)To further protect the pressure vessel in the event of failure of the reducing value or device, at least one safety value having a capacity sufficient to release all the steam, vapour or gas without undue pressure rise as determined by the pressure at the source of supply and the size of the pipe connected the source of supply, shall be fitted on the low pressure side of the reducing valve.
