Calculating charge size for A2L refrigerants

Source: Answers to the questions asked during the A2L webinar on May 7 organised by Climalife in partnership with Tecumseh and Honeywell




Pierre-Emmanuel Danet, Technical Support Manager at Climalife
Alain Lelièvre-Damit, Purchase & Quota Manager at Climalife
Regis Leportier, Technical Programs Director at Tecumseh Europe
Jean De Bernardi, Technical Team Lead at Honeywell Refrigerants




How much is per kilo?


The charges are calculated according to EN 378. They will be different depending on the access category and the location of the equipment according to EN 378.
For category A and class 2L fluids, the higher the lower flammability limit, the higher the permissible load. In this category A2L, R-455A has the highest value with an LFL of 0.430 kg/m3.


See attachement : Comparative curves according to refrigerant type




Do you see charge limits as a problem in applying A2L's in walk in cold and freezer rooms?
Calculation of the permissible charges is to be carried out in accordance with the recommendations of EN 378-1.
The information and calculation method can be found in Annex C - Requirements for refrigerant charge limits and safety classifications with the information on refrigerants in Annex E. (See process flow diagram on page 3 of the A2L Good Practice Guide).
The possible charges make it possible to respond to the payload quantities in cold rooms.




What is the legal requirement for the use of flammable refrigerant gases around minimum ventilation, and how can it be determined?
The installation of a ventilation system will allow for a higher charge size. The permissible refrigerant content in a room is calculated according to the recommendations of EN 378 based on its toxicity (ATEL / ODL) * or flammability (LFL*). Annex E contains this information as well as the practical limit (in Kg/m3) which is the simplified value of a concentration used to determine by a simplified calculation the maximum acceptable quantity of refrigerant in an occupied space.
The Refrigerant Concentration Limit (RCL) is the maximum concentration of refrigerant in air set to reduce the risk of acute toxicity, asphyxiation and ignition, according to Article C.3 of EN 378.

*ATEL: maximum recommended concentration of refrigerant intended to reduce the risk of acute toxicity to humans in the event of discharge of a refrigerant.
*ODL / concentration of a refrigerant or other gas resulting in the presence of insufficient oxygen for normal breathing.
*Lower flammable limit: LFL: minimum concentration of refrigerant capable of propagating a flame in a homogeneous mixture of refrigerant and air.

See example: Refrigerant charges according to the type of installation.




One of the slides mentioned the use of "2 safety measures" to offset the charge limits of EN378. What is the refrence for this information?
According to Article C.3.1 et C3.2 of EN 378 : another solution for managing the risks associated with refrigeration systems in occupied spaces.




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