2012 年 29 巻 4 号 p. 401-411
R 1234yf and R 32 are expected as the alternative refrigerants for protection of the global environment. R 1234yf and R 32 have low flammability by comparison with the other HFC refrigerants now in worldwide use. We examined the fire hazard and characteristic of HF generation in the case that a wall mounted type air conditioning system having these alternative refrigerants is used with the fossil-fuel heating systems in the same room (corresponding to 4 pieces and half of tatami mats) at the same time. Both the cases of R 1234yf and R 32, concentration of refrigerant in the room was not more than the lower flammable limit (LFL) of refrigerants even if the all amount of refrigerants leaked from an air conditioning system to the room, so the flame propagation of refrigerants was not confirmed. However, generation of HF over the permissive concentration (3 ppm) was confirmed regardless of the varieties of refrigerants including R 410A due to the contact between refrigerants and heating part in the fossil-fuel heating systems. It was experimentally confirmed that productivity of HF from R 32 per unit time and mass was comparatively larger than that of R 1234yf and R 410A.