Frequently Asked Questions

Frequently Asked Questions



Ethylene is a colourless gas that does not smell at low concentrations. It is a simple molecule CH2 =CH2 , that is very volatile (4.2 x 10 6 Pa). At high concentrations above 2.7% (27000 ppm) it becomes explosive, but the Restrain generator is not capable to reach even only a fraction of that concentration. Thus the use of the Restrain Generator can not lead to explosions. Note however that its fuel is flammable, no open fires (including smoking) or sparks are allowed at refilling.


Ethylene is also a very natural gas. It is produced in nature by bacteria and fungi in the soil and by all plants. The highest exposure of ethylene a person can expect is in towns and on motorways from motor car engines.


Ethylene is also a very safe gas. It was previously used for tens of years as an anaesthetic at concentrations of 70-80%. Now it has been replaced by modern anaesthetics, mostly due to the high explosion risk of such high concentrations and not at all for toxicology reasons.
Bananas are ripened by ethylene gas and most apple stores contain much more ethylene than used by the Restrain process.


Ethylene is also not persistent in the environment. The half-life of the molecule in the outside air is around 15 hours, due to the action of UV light, which breaks up the molecule quite rapidly. Also release of ethylene from stores does not affect nearby crops, calculations have shown that the dilution with increased distance is so rapid, that the already low concentration used for storage purposes of potatoes and onions, can not have any effects on nearby crops.


Finally, ethylene does not leave any residues on potatoes and onions, once the storage is completed. Firstly ethylene does not penetrate significantly into the foodstuff and secondly its high volatility allows it to evaporate rapidly into the air.