This gassing line is using compressed inert gas ( an ideal gas) as a propellant. If it was using liquified propellants such as butane, it would not be allowed to operate in the main building.
Leaks of propellant vapour from faulty cans can happen after filling. These can be detected in a water bath as bubbles (see page 6).
Some production lines use gas detection equipment that can detect a few parts per million of gas at high speed, without even stopping the conveyor belts. Butane absorbs certain wavelengths of infrared light, so by shining an infrared laser through the gas any absorption will be detected as a drop in the light level by an infrared detector. The laser takes 100,000 samples per second and is so fast that it can trigger an ejector to eject the leaking aerosol from the production line.
Image: Cascade Technologies Ltd.
The image on the right shows the gas sampling arch. Gas is sucked into the holes in the arch at high speed. If the system detects a leak the aerosol is pushed off the production line.The whole process takes less than 1/8th of a second.
Image: Cascade Technologies
Even with many safety systems there is still a chance that a spark could start a fire or cause an explosion.
Rubbing plastics together is a good way to make electrostatic sparks. The conveyor belts in aerosol factories are made from plastic containing conductive carbon. Any electrical charge is conducted away to the metal parts of the machinery. Airport baggage carousels use the same conductive plastic for the conveyor belts.
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