Technical aerosols

The F-Gas Regulation 517/2014 banned the use of HFCs with GWP of 150 or more, in technical aerosols from 1 January 2018, except when required to meet national safety standards or when used for medical applications. Technical aerosols (excluding medical applications) are used in a range of applications including industrial lubricants, mould release agents during product manufacturing, pressure dusters and aircraft insecticide sprays. An aerosol is pressurized with a propellant that expels its contents through a nozzle. In addition to the propellant, formulations may include solvents and other substances to achieve the required technical performance. Liquified compressed gases are widely used as they maintain a relatively constant pressure as the contents are used up, maintaining consistent droplet size and spray rate which may be required for technical aerosols. Compressed gases, such as carbon dioxide, cannot produce a consistent particle size and spray rate which limits their applicability.

 

Photo © Shutterstock – Cefic

The vast majority of aerosols use highly flammable propellants (hydrocarbons and DME), but technical aerosols may require the use of low or non-flammable propellants, due to the risk of ignition or the quantities used potentially creating an ignitable gas mixture. Non-flammable HFCs were previously used but these all have GWPs >150.
For uses where moderate flammability is acceptable then HFC-152a may be used as it has a GWP <150. Where a non-flammable propellant is required then HFOs are being used, alone or as a propellant blend. Two HFOs propellants, which are classified as non-flammable for this use, are HFO-1234ze(E), with a GWP <1 (AR5 value) and HFO-1336mzz(Z) with a GWP of 2 (AR5 value). The applicable tests for non-flammability for aerosol use are different to those used for refrigerant safety classification, which is why HFO-1234ze(E) is considered a non-flammable propellant, but a mildly flammable refrigerant. Other HFOs or HCFOs may be used as solvents in the aerosol formulation.