If there is no barrier, what minimum distance must be maintained between oxygen cylinders and fuel-gas cylinders?

• A. 10 feet
• B. 15 feet
• C. 25 feet
• D. 20 feet

Answer: (D)

Keeping oxidizers and fuel gases apart reduces the risk of rapid, cross-ignition if a leak or heat source is present. Oxygen accelerates combustion, while fuel gas is flammable, so if they’re too close a small leak or spark can ignite the other cylinder and potentially involve both cylinders. Without any barrier, a minimum separation of twenty feet provides a safety margin that slows or prevents flame transfer and reduces heat exposure between the two types of cylinders. If a barrier were present, closer storage could be allowed under code, but with no barrier, twenty feet is the required distance.