Shrink wrapping, which consists of using heat shrink film, makes it possible to package parcels of all sizes. These range from pallets to aircraft engines, furniture, and the containment of large volumes, such as buildings and ships. Tool ranges have been developed to enable professionals to work in the best possible conditions. The heat guns for shrink wrapping are handy and light, and their temperature must be adapted to work fast, without the risk of piercing the shrink film. These tools must be used with the most suitable gas.
Which gas should be chosen for shrink wrapping?
Manufacturers of heat guns for shrink wrapping had a choice of two gases to operate their tools: propylene or propane.
The liquefaction point of propylene is -47.6 °C, which is why it is used instead of butane (whose liquefaction point is -0.5 °C) in very cold countries. However, like most simple hydrocarbons, propylene is colourless, odourless and highly flammable.
On the other hand, propylene is difficult to store and transport. This is why Express has decided to develop its range of tools for shrink wrapping with propane gas.
Why is propane gas best suited for shrink wrapping?
Propane is the only gas that generates sufficient flow and pressure. At an ambient temperature of 20 °C, it can generate a pressure of 7 bar, whereas butane, at a comparable temperature, produces a pressure of only 1.5 bar at most.
In order for the propane to no longer generate pressure, i.e. 0 bar, the temperature must be reduced to – 43 °C.
Propane conditioning
Propane is easily packaged and poses no storage problems. This benefit applies to both gas distributors and users. Companies that are professional packers and containment professionals sometimes need to store large supplies, which is possible with propane, provided basic safety precautions are followed.
For the user, propane is offered in cylinders of different capacities, allowing choice depending on use. The bottle is connected by a rubber hose that can measure 10 meters or more. This gives the user of the heat gun great freedom of movement, which enables treating large surfaces, even at a height, for the containment of buildings and ships.
The quality of the flame
Propane alone provides sufficient temperature. Using propane and ambient air can already reach a temperature of 1,800 °C, whereas for shrink wrapping, a temperature of 300 °C is sufficient to process polypropylene shrink films of any thickness.
It is therefore more interesting to go for an aeropropane flame than to look for combinations, such as the oxy-propane type mixture which would not provide any improvement.
Propane, another good deal…
The price of propane
The consideration of price is not unimportant either. Propane gas is always readily available and can be found everywhere. It remains the cheapest gas, and therefore the most valuable for shrink wrapping companies that consume it in large quantities.
For shrink wrapping, the question of the choice of gas does not arise: the best is obviously propane!
