Hi Motorhead I used to deal with these machines in a previous life, but for the life of me i cannot remember the temperatures etc. I assume you are refering to shrink tunnels. The only reference I know is in BS EN 415-5:2006 Part 5: Wrapping Machines (I have cut and paste the section below). Hope it helps! 5.15.4 Product Overheating of flammable and/or explosive products as defined by Directives 94/55 EC and 67/548/EEC shall be avoided by the following means: a) manufacturer should provide details of the maximum working temperature for the equipment, the maximum thermal output of the heaters, and the minimum conveyor speed. The instructions should include a description of the safe working method for setting up the machine. This should start with setting the belt speed, then running the machine at a low temperature setting, then progressively increasing the temperature until a satisfactory shrink wrap is achieved. This should be done while monitoring the product to ensure that is not overheated such that it may, for example, approach its auto-ignition temperature; b) run out function shall be incorporated to enable all products to be discharged before the conveyor stops; c) in the event of an emergency e.g. loss of mains power the belt shall move by a power reserve (e.g. pneumatic or electric battery) to enable all products to be discharged before the conveyor stops; d) alternatively once power has been isolated the tunnel or tank should be capable of being opened to enable removal of products using protective equipment or to allow the rapid dissipation of heat; e) automatic carbon dioxide sprayers or other suitable fire extinguishing equipment shall be mounted if there is a significant risk of fire; f) to prevent fire hazard a high temperature sensor and associated high temperature cut off shall be installed independently from thermostatic control to minimise the risk of the product catching fire; g) for safety requirements regarding external temperature of the exposed parts of the machine refer to 5.2.3

Andy, if the aerosols have flammable propellant (almost all do) then tread very carefully when thinking about shring wrapping. A risk assessment may well conclude that the risk of leaking propellant (and contents too) needs a leak detection system to be in place prior to any heat exposure, linked to shutdown/alarm and maybe auto-suppression too. Are you filling and gassing yourselves or are you receiving the aerosols and splitting the packages down for resale?

Shrink wrapping via tunnel with appropriate safe guards is not a problem, cans are leak tested prior to shipping. IMO, the equipment under consideration is not suitable as there is the potential for human error i.e forgetting to remove the cans from the heater/wrapper.