With Daikin now offering three units using the new low GWP refrigerant in Europe, Daikin has produced a white paper for installation and service personnel.
Although still very much in its infancy in Europe, Daikin pioneered the launch of the first worldwide air conditioners with R32 refrigerant at the end of 2012 in Japan. Several million units have since been installed and the availability of R32 units expanded to other countries including Australia, New Zealand, India, Thailand, Vietnam, the Philippines, Malaysia and Indonesia.
Despite concerns over its “mild flammability”, Daikin insists that the installation and service practices for R32 are similar to those for R410A. “As it is a pure refrigerant, working with this new refrigerant could not be simpler,” Daikin says in the white paper. “R32 is also easier to recover and reuse,” it says.
Working pressures for R32 are very similar to R410A and, when charging, R32 is easier to handle, says Daikin, as, unlike R410A, it can be charged in both a gas and a liquid state.
Daikin also explains why R32 is classified as A2L “mildly flammable” while safety data sheets say it is extremely flammable. International Standard ISO 817:2014 now divides the flammability of refrigerants into four categories: Class 1 – no flame propagation; Class 2L – lower flammability; Class 2 – flammable: Class 3 – higher flammability. These classifications are commonly known as non flammable, mildly flammable, flammable and highly flammable.
“This classification is based on several criteria, such as the lower flammable limit, combustion heat and burning velocity,” says Daikin. This classification is used as a reference in other standards which look at the application of equipment, for example the installation of an air conditioner in a certain room size and building type.”
The flammability classification shown on Material Safety Data Sheets is determined in accordance with the Globally Harmonized System of Classification and Labelling of Chemicals (GHS).
“The GHS classification of flammable gases uses a more simplistic approach mainly used as a guidance for international transport rules,” Daikin insists.
Gases are classified only by the percentage concentration of gas required to create a flammable mixture in air. Other important factors such as how easy the gas is to ignite or how it behaves once ignited are not taken into consideration.
“This is why, on safety data sheets, R32 is classified as extremely flammable, like propane (R290) or isobutane (R600a) although in reality their flammability risk is quite different,” says Daikin.
That said, users of R32, like all other refrigerants, must follow European and national safety rules, as well as instructions from the manufacturers of R32 equipment and from the suppliers of R32 refrigerant cylinders,
Even though only “mildly flammable”, Daikin insists that certain extra precautions need to be taken with R32.
R32 will not ignite if the concentration level in a room stays below the lower flammable limit (0.306kg/m³). International and European safety legislation and standards such as EN60335-2-40 and EN378 define guidelines for remaining well below the lower flammable limit in the case of accidental leakage.
Equipment and installation and service instructions are said to be similar to R410A – ventilation required, no smoking, etc. When repairing an indoor unit, a draught needs to be created from indoors to outdoors to provide good ventilation. Daikin advises that this can be created by opening all windows and doors in the building.
Tools like manifolds, leak detectors and recovery pumps also need to be suitable for use with R32. Engineers in any doubt need to check with the tool supplier. In some cases, a cylinder adapter may be required as the R32 refrigerant cylinder may have a different thread.
The R32 white paper can be read and downloaded here.