(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 vessels with any other source of supply, shall be fitted with a suitable pressure reducing valve or other suitable automatic device to prevent the maximum permissible working pressure of the pressure vessel being exceeded.(b)To further protect the pressure vessels in the event of failure of the reducing value or device, at least one safety valve having a capacity sufficient to release all the steam, vapour or gas without under pressure rise as determined by the pressure at the source supply and the size of the pipe connecting the source of supply, shall be fitted on the low pressure side of the reducing valve.
