With the world moving towards low GWP refrigerants, air conditioning and refrigeration institutes, associations and universities across Japan have been carrying out risk assessment studies on the new so-called “mildly flammable” A2L refrigerants.
Japanese air conditioning manufacturers have been leading the way in adopting the single component, low GWP, HFC R32 as the replacement for R410A in small splits but most national and international standards, while in the process of being revised, currently prevent its use in larger systems.
Led by Daikin, small splits running on R32 have already been introduced in the Far East, Australia and Europe.
Amongst a number of risk assessment studies, the Japan Refrigeration and Air Conditioning Industry Association (JRAIA) has been looking into the use of R32 and R1234yf in VRF systems, exploring the probability of refrigerant leaks, evaluating ignition sources and investigating methods for calculating the probability of fire.
In its latest interim report on R32, VRF systems using this gas were found to be within allowable levels for ceiling-installed units in offices – which account for 95% of installations in Japan – provided that there was mechanical ventilation.
However, the risks exceeded the allowable values for floor-standing units in restaurants and ceiling-installed units in karaoke shops where natural ventilation does not usually exist in order to prevent sound leakage.
In addition, the risks exceeded the allowable values for outdoor units in semi-underground and machinery room installations.
The next step for JRAIA is to evaluate the effect of natural ventilation as a safety measure for floor-standing units that are prone to refrigerant accumulation at floor level and proceed with the risk assessment for R1234yf. The association says it plans to enact safety guidelines in the autumn to facilitate the safe use of mildly flammable refrigerants in VRF systems.