Section R. 408.17127 - Relief valvesRule 7127.
(1) Where a pressure reducing valve is used, not less than 1 relief valve shall be provided adjacent to the reducing valve on the low pressure side.(2) The relief valve shall vent to an area which will not create a hazard to an employee. The vent shall be the same size as the relief valve outlet and as short and direct as possible.(3) The combined discharge capacity of relief valves shall be such that the pressure rating of the lower pressure piping and equipment will not be exceeded if the reducing valve should fail to function.Mich. Admin. Code R. 408.17127