Section 67(5)(b) in The M.P. Factories Rules, 1962
(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.