The charge limits of A2L refrigerant gases are divided into three different sections; depending on the section in which the charge of the refrigerant installation is located, legal specifications are determined that must be met to avoid the risk of flammability. They are summarized in the following table:
Load below mI | Load above mI and below mII | Load above mII |
|
|---|---|---|---|
| CASE I: Exclusion | X | ||
| CASE II: Needs to install additional safety measures | X | X | |
| CASO III: ATEX certification is required | X | X | X |
Case 1. The refrigerant installation is excluded from the regulation
When the refrigerant load is lower than the lower flammability limit (LFL) x 6 m3 described in the following table, the refrigerant installation is considered to have a very low flammability risk, so no preventive measures are required (it is excluded from the application of the UNE-EN-378 standard).
Refrigerant | LFL kg/m3 | Maximum load (kg) |
|---|---|---|
| R-32 | 0,307 | 1,842 |
| R-1234ze | 0,303 | 1,818 |
| R-452B | 0,310 | 1,860 |
| R454A | 0,278 | 1,668 |
| R-454B | 0,301 | 1,806 |
| R-454C | 0,291 | 1,746 |
| R-455A | 0,423 | 2,538 |
The exclusion of the refrigerant system from the application of the UNE-EN-378 standard does not mean that the whole installation is excluded. For this purpose, the design, safety and communication conditions specified in the standards for such installation must be taken into account. Examples of exclusion cases are installations with low compressor power, such as bottle racks, under counters or vending machines.
In case the loads defined in the table above are exceeded, the maximum load will be calculated according to the UNE-EN 378 standard, taking into account the flammability and toxicity of the refrigerant, and a risk assessment must be carried out taking the corrective standards to be within the regulations, thus entering in case II.
Case 2. Need to install an additional safety system
In the case of exceeding the specified load, without being exceeded in terms of toxicity, a flammability risk analysis must be carried out in accordance with the UNE-EN-378 standard. If the result of this analysis is a non-hazardous area, for example an outdoor area such as terraces, roofs, etc., the refrigeration plant can be used with the load limits according to the formula in the table. If, on the other hand, the area is classified as ATEX zone 0, 1 or 2, the refrigeration plant must be certified in accordance with the explosive atmosphere regulations.
If the refrigeration plant is not ATEX and the maximum load specified in the table above is to be exceeded, it is possible to use the plant provided that additional or corrective measures are taken, such as the modification of variables to exclude it from the ATEX zone, or an additional safety measure such as the installation of a refrigerant saturation sensor to prevent an explosive mixture.
The exclusion of the refrigeration equipment from the application of the regulation does not mean that the whole installation is excluded from the application of the regulation. For this purpose, the design, safety and communication conditions specified in the UNE-EN-378 standard must be taken into account.
In Cooling equipments of this second case which are equipped with defrosting resistance, it is necessary to assure that their surfaces do not exceed the temperature of 100K; for example placing a clixon (safety temperature sensor) that in case of an excessive temperature increase, disconnects the electrical supply. The coil manufacturer, in this case Sereva, designs the evaporator in such a way that the surface temperature of the resistors does not exceed this temperature.
Case 3: need for ATEX certification
If the refrigerant load exceeds the maximum load (mII) calculated according to Annex C of the UNE-EN 378-1 standard, a flammability risk analysis must be carried out in accordance with the UNE 60079-10-1 standard to determine the classification of the ATEX zone in which the refrigeration equipment will operate. Once it is determined in which zone the refrigeration installation will operate, zone 0, 1 or 2, it will be equipped and configured according to this standard to obtain the ATEX certification.