4.3.1 General requirements for both domestic/residential and commercial/industrial installations

The following general requirements apply to all systems whatever their location and should be taken into account in assessing that the risk is acceptable and has been reduced to as low as is reasonably practicable:

• The installation should be placed on firm foundations, capable of supporting it;
• Ensure that any area, enclosure or housing etc into which hydrogen may leak is designed to prevent the gas becoming trapped and is equipped with effective high- and low-ventilation;
• The installation components, in particularly vent or exhaust outlets, should be sited giving due attention to adjoining doors, windows, outdoor air intakes and other openings into buildings;
• Air intakes shall be located in such a way that the fuel cell is not adversely affected by other exhausts, gases or contaminants;
• Exhaust outlet(s) should not be directed onto walkways or other paths of pedestrian travel
• Security barriers, fences, landscaping and other enclosures should not affect the required flow into or exhaust out of the installation;
• Any vents (from pressure relief valves or bursting joints, etc) should be piped to a safe area and any points of possible leakage should be in an area where any gas cannot accumulate or is freely ventilated. In addition care should be taken that vents do not release hydrogen adjacent to walls or along the ground as this may increase the extent of the flammable cloud or flame (Appendix A6);
• Safety/separation distances where a release is foreseeable during normal operation should be determined on a case-by-case basis. Separation distances should be measured horizontally from those points in the system where, in the course of operation, an escape of hydrogen may occur. The most recent version of an appropriate code should be consulted for additional information on the appropriate use of separation distances;
• In circumstances where it is not practicable to use minimum separation distances, an acceptable situation may be achieved through the use of fire-resistant barriers, fire compartments, fire resistance, room-sealed appliances, appliance compartments, or other hydrogen safety engineering or risk reduction techniques. Work continues to validate new distances for future revisions. Case studies, experimental and modelling work within the HYPER project aim to assist in safety and procedural issues therefore contributing to the validation of new separation distances. Case studies are provided in Appendix A3. A summary of the experimental results is provided in Appendix A5. A summary of the modelling results is provided in Apendix A6.
• For all indoor locations the installation should comply with all applicable building regulations, particularly as they relate to heating and electrical appliances, fuel storage systems, conservation of fuel and power, protection against pollution, and more generally to securing reasonable standards of health and safety for people in or about buildings and any others who may be affected by buildings or matter connected with buildings.
• For all indoor fuel cell locations, liquefied and gaseous hydrogen storage should either be located outside in the open air, in an appropriate dedicated unoccupied storage building, in an appropriately ventilated enclosure, or in a purpose designed indoor or underground facility, and should conform to recognised guidance.