Retrofit to A2L in no or limited ex-zone
Example task: An existing small refrigeration system has to be retrofitted from R404A to the A2L flammable refrigerant R454C. An Ex zone should be avoided as far as possible.
Information
A2L refrigerant can only be used in existing systems, where safety standards and local regulations allow this. The necessary safety measures have to be taken. This can in some cases be sufficient room size, sufficient ventilation or a gas warning system shutting down the electrics in the sensitive area and giving alarm inside and outside the room. This risk evaluation has to be done before the retrofit!
A2L refrigerant can only be used in existing systems, where safety standards and local regulations allow this.
The necessary safety measures have to be taken. This can in some cases be sufficient room size, sufficient ventilation or a gas warning system shutting down the electrics in the sensitive area and giving alarm inside and outside the room.
This risk evaluation has to be done before the retrofit!
Special tools or preconditions:
- Mobile A2L gas detector
- A2L leak detector
- A2L fire extinguisher
- A2L recovery equipment
- Vacuum pump with external switch, outside room
- Extra fan
- A2L anti-sparking tool – not necessary
Working steps or preconditions:
- Educated worker
- Check compatibility of parts with new refrigerant A2L
- a. doublecheck with parts manufacturers or their documentation/apps
- Read / inform for risk assessment of system
- Check ventilation of site or room, A2L ready?
- Check location of main switch
- Have A2L fire extinguisher ready
- Put warning sign to notify work in progress, especially where refrigerant might be released
- Power off compressor / system
- Leak test system with R404A sniffer
- Pump down system and compressor
- Remove R404A with recovery machine to the lowest possible limit (residual R404A at very low level can stay in the system)
- Oil heater on
- Exchange oil, if miscoloured
- Evacuate system
- Exchange parts necessary
- Tightness test with dry nitrogen
- Test pressure switches
- a. Set low pressure cut out to avoid operation in vacuum
- Evacuate system
- Start charging the system with A2L refrigerant
- a. Now have a A2L gas detector with you and ventilation on
- Sticker for flammable gas on compressor and system
- Put sticker on technical room door
- Update the system log book with new refrigerant and charge
- a. Add new pressure switch settings
- Update system operating instructions with new refrigerant
- Update risk assessment for operation with A2L refrigerant
More details on retrofit procedure and material compatibility can be found in A-540.