Research was carried out into how ventilation in the rear of enclosed vans affects the build-up of acetylene gas. This provides essential information to those assessing the risk of carrying acetylene in vehicles. This will include employers, managers, supervisors, employees and the self employed involved in the use of acetylene where this might involved carrying bottles in vehicles.
Acetylene has an unusually wide explosive limit which means that even a small leak in an enclosed space can cause an explosive atmosphere to build up. Acetylene cylinders should therefore be transported in open vehicles where it is reasonably practicable.
If this is not reasonably practicable and acetylene cylinders or an oxy/acetylene set has to be carried in the rear of a closed van, you must ensure that there is ventilation fitted to the load space of the vehicle. This can be a low level ventilation grill and rotary roof vent which will increase the air changeover rate in the load space when the vehicle is parked or moving.
Note: A large release, such as when valves are not closed or do not close properly, will cause an explosive atmosphere to develop quickly even with ventilation (although the gas may dissipate once the cylinder is empty). Following industry guidance on removing the hoses from the cylinders reduces the risk of this not being noticed.