[ safety ]
Table 1 : Electrical area classification around Class 1 , Group B ( hydrogen ) systems 10
Hydrogen Vent Outlet
Location
Distance Measured Spherically from the Source |
Electrical Area Classification |
Within 1 m |
Class 1 Division 1 |
Between 1 m to 4.6 m Class 1 Division 2
Hydrogen Storage Equipment
Inside Vessel Class 1 Division 1 Within 4.6 m Class 1 Division 2
A hydrogen storage system requires sufficient spacing from any potentially hazardous exposures . These distances depend not only on the hazards themselves , but also on the pressure and amount of hydrogen being stored , as well as the minimum pipe size in the system . Distances may also be reduced with the use of a non-combustible firerated barrier interrupting the line of sight between hazards with a maximum of two sides at 90 ° angles or three sides at 135 ° angles ( see Figure 1 for details ). The reader can refer to NFPA 2 and the Occupational Safety and Health Administration ( OSHA ) 1910.103 standard for detailed descriptions of distances to hazardous exposures . 4 and filled with concrete . Spacing between posts should be kept to a maximum of 1.2 m ( 4 ft ) between each other and a minimum of 0.9 m ( 3 ft ) from the tank . The footing is required to be a minimum of 0.9 m ( 3 ft ) deep and 380 mm ( 15 in ) diameter . The posts should have a minimum height of 0.9 m ( 3 ft ). 4 Where the compressed gas vessel is located in an area that is open to the public , the storage and use area should be fenced and locked with access restricted to supplier and user personnel only . Although not necessary to fence a vessel if it is in a user-secure area and not accessible by the public , fencing may still be used for security based on personnel access patterns . 8
A storage tank , connected piping , valves , fittings , and use areas should also be protected from potential vehicular damage by installing guard posts or bollards . Posts should be constructed of steel with a minimum diameter of 102 mm ( 4 in )
Hazard identification signs should be mounted on stationary aboveground tanks and containers and on entrances to locations where they are stored . In addition , the area where a hydrogen system is located is required to be permanently placarded as follows :
Fig 3 . Electrical area classification in area around a hydrogen vent stack ( left ) or storage tank ( right ) 10
Hydrogen Tech World | Issue 8 | February 2023 15