National Fire Protection Association 58 - Gas Code

8.4.2 Protection of Cylinders

8.4.2.1* Cylinders at a location open to the public shall be protected by either of the following:
(1) An enclosure in accordance with 6.19.4.2
(2) A lockable ventilated enclosure of metal exterior construction

Please consult your local authority having jurisdiction with your questions and for guidance in conforming to laws as they apply to your application. This is only meant for a reference and does not imply a warranty.