Michigan Administrative Code
Department - Licensing and Regulatory Affairs
Bureau of Fire Services
Storage and Handling of Gaseous and Liquefied Hydrogen Systems
Part 2 - STORAGE AND HANDLING OF GASEOUS HYDROGEN NFPA 50A
Chapter 4 - Design considerations at specific locations
Section R. 29.7040 - Special rooms
Current through Vol. 24-16, September 15, 2024
Rule 40. Sections 4-3.2 to 4-3.6 are reproduced from NFPA 50A, and sections 4-3.1, 4-3.7 to 4-3.9, and table 4-3.9 of the storage and handling of gaseous and Liquefied H2 code are added as follows:
4-3 Special rooms.
4-3.1 Floor, walls, and ceiling shall be constructed of noncombustible or limited-combustible materials. Interior walls or partitions shall have a fire resistance rating of at least 2 hours, shall be continuous from floor to ceiling, and shall be securely anchored. At least 1 wall shall be an exterior wall. Windows and doors shall be located so as to be readily accessible in case of emergency.
Exception: Window glazing may be of plastic.
4-3.1.1 If access to the room from outside the primary structure is not possible, access from within the primary structure shall be made through 1 vapor-sealing 2-hour self-closing fire door.
4-3.2 Ventilation shall be as provided in section 4-2.2.
4-3.3 Explosion venting shall be as provided in section 4-2.3.
4-3.4 There shall be no sources of ignition from open flames, electrical equipment, or heating equipment.
4-3.5 Electrical equipment shall be in accordance with Article 501 of NFPA 70, National Electrical Code, for Class I, Division 2 locations.
4-3.6 Heating, if provided, shall be by steam, hot water, or indirect means except that electrical heating shall be permitted to be used if in compliance with 4-3.5.
4-3.7 Room ventilation.
4-3.7.1 The ventilation shall be at least 1 cubic feet/minute/square feet (0.3 cubic meters/minute/square meters) of room area, but not less than 1 cubic foot/minute/12 cubic feet (0.3 cubic meters/minute/3.7 cubic meters) of room volume and shall be designed such that an accumulation of H2 at a concentration equal to or greater than 25% of the lower flammability limit shall not occur in any part of the room.
4-3.7.2 Where installed, a gas detection system shall be equipped to sound an alarm and visually indicate when a maximum of 25% of the lower flammable limit is reached. At 40% of the lower flammable limit the gas detection system shall shut down the hydrogen system and provide notification to the system operator.
4-3.7.3 Any failure of the ventilation system shall immediately shut down the fueling system and provide notification to the system operator. Reactivation of the fueling system shall be by manual restart and shall be conducted by trained personnel.
4-3.7.4 The gas detection system shall function during ventilation system maintenance operations.
4-3.7.5 A ventilation system for a room within or attached to another building shall be designed to ensure that all areas serviced by the ventilation system meet performance requirements in accordance with section 4-3.7 during the normal operating conditions and during alarm conditions.
4-3.8 Warning signs.
4-3.8.1 Access doors shall have warning signs with the words "WARNING - NO SMOKING - NON ODORIZED FLAMMABLE GAS - NO OPEN FLAMES. The wording shall be in plainly legible, bright red letters not less than 1 inch (2.54 centimeters) high on a white background.
4-3.9 Indoor attended fast-fill fueling.
4-3.9.1 Attended indoor fast-fill fueling system shall be in accordance with subsections (a) to (k) of this section.
(a) Gas storage equipment shall be located outdoors unless approved by the department. Gas processing and compression equipment shall be listed or approved for indoor use or located outdoors.
(b) An emergency manual shutdown device shall be located in the dispensing area not less than 20 feet (6.1 meters) and not more than 100 feet (30.5 meters) in the path of egress from the dispensing area. Actuation of the emergency manual shutdown device shall perform in accordance with subsection (h) of this section.
(c) The dispenser shall be equipped with a gas detection system which shall actuate in accordance with subsection (h) of this section when a maximum of 25% of LFL is detected (1% H2 in air).
(d) The dispenser shall be equipped with a leak detection system capable of identifying a leak from the dispensing system outside the dispenser housing by conducting a pre-fill pressure test. The leak detection must be capable of detecting a minimum leak rate of 1.9 gallons/minute and shall actuate in accordance with subsection (h) of this section when a leak is detected.
(e) Whether the fill is communicated or non-communicated, the dispensing system must be listed, labeled, or approved to insure that the fills are protective of the safety of the temperature, pressure and flow rate of the on-board fuel system during fueling.
(f) The dispensing area shall be equipped with a fire detection system and shall actuate in accordance with subsection (h) of this section if a fire is detected.
(g) A ventilation system shall be installed for the dispensing area. The ventilation system shall be capable of delivering ventilation air as provided in section 4.3.7. The ventilation system shall operate prior to dispenser operation, during fueling, and for at least 1 minute after fueling has been completed. The ventilation flow rate shall be monitored. Failure or reduction of the ventilation flow rate below the required flow rate shall shut down the dispensing system.
Exception: A dispensing area ventilation system is not required when the fuel delivery per refueling event is less than those listed in table 4-3.9. Table 4-3.9
| Room Size (m3) | Maximum fuel delivery per refueling event that does not require room ventilation (kg) |
| 1000 | 0.8 |
| 2000 | 1.7 |
| 3000 | 2.5 |
| 4000 | 3.3 |
| 5000 | 4.2 |
(h) The actuation of any 1 of the systems listed in subsections (b) to (g) of this section shall be in accordance with table 4-3.9, and shall shut down the dispenser, stop the flow of gas into the room, and start or continue to run the ventilation system, if required.
(i) Interior walls, doors, and window openings within 15 feet (4.6 meters) of the dispenser shall be constructed of materials having a fire rating of at least 2 hours. Wall penetrations shall require use of listed fire rated equipment.
(j) The owner/operator shall not allow hot work/open flames within 15 feet (4.6 meters) of the refueling location unless the dispenser is shut down, depressurized, and purged.
(k) If H2 is to be removed from the vehicle storage system, H2 shall be discharged into a closed transfer system or vented outdoors in accordance with CGA G-5.5, "Hydrogen Vent Systems", adopted by reference in section 8-1.
