5-12
FIELD WORK INSTRUCTION
5.8 Caution on Refrigerant Leakage
(1) Maximum Permissible Concentration of HCFC Gas
The refrigerant R407C (or R22), charged in the SET-FREE FSG, FS1/FS3, FS5 and FXG/FX3 system,
is an incombustible and non-toxic gas. However, if leakage occurs and gas fills a room, it may cause
suffocation.
The maximum permissible concentration of HCFC gas, R407C in air is 0.31 kg/m
3
, R22 in air is
0.3 kg/m
3
, according to the refrigeration and air conditioning facility standard (KHK S 0010) by the
KHK (High Pressure Gas Protection Association) Japan.
Therefore, some effective measure must be taken to lower the R407C or R22 concentration in air
below 0.3 kg/m
3
, in case of leakage.
(2) Calculation of Refrigerant Concentration
(a) Calculate the total quantity of refrigerant R (kg) charged in the system connecting all the indoor
units of rooms to be air conditioned.
(b) Calculate the room volume V (m
3
) of each objective room.
(c) Calculate the refrigerant concentration C (kg/m
3
) of the room according to the following equation.
(3) Countermeasure for Refrigerant Leakage According to KHK Standards
The facility shall be arranged as follows referring to the KHK standards, so that the refrigerant
concentration will be below 0.3 kg/m
3
.
(a) Provide a shutterless opening which will allow fresh air to circulate into the room.
(b) Provide a doorless opening of 0.15% or more size to the floor area.
(c) Provide a ventilator, linked with a gas leak detector, of 0.4 m
3
/min. or more ventilating capacity per
Japanese Refrigeration Ton (= compressor displacement m
3
/h / 8.5 (R22) or 9.8 (R407C)) of the air
conditioning system utilizing refrigerant R22.
<FSG, FSG1/FS3, FS5 Series>
RAS-5FSG ............................ 2.15 / 2.15 ton (50Hz / 60Hz)
RAS-5FS3............................. 2.48 / 2.48 ton
RAS-8FSG ............................ 3.74 / 3.98 ton
RAS-8FS3............................. 4.31 / 4.59 ton
RAS-10FSG .......................... 4.01 / 4.31 ton
RAS-10FS3........................... 4.63 / 4.97 ton
RAS-16FSG .......................... 5.78 / 6.44 ton
RAS-16FS3........................... 6.66 / 7.42 ton
RAS-20FSG .......................... 7.36 / 8.35 ton
RAS-20FS3........................... 8.49 / 9.63 ton
RAS-24FSG1 ........................ 8.72 / 9.96 ton
RAS-24FS5........................... 10.05 / 11.48 ton
RAS-30FSG1 ........................ 10.55 / 12.17 ton
RAS-30FS5........................... 12.16 / 14.03 ton
<FXG/FX3 Series>
RAS-8FXG ............................ 3.74 ton (50Hz)
RAS-8FX3............................. 4.31 ton
RAS-10FXG .......................... 4.01 ton
RAS-10FX3........................... 4.63 ton
(d) Pay a special attention to the place, such as a basement, etc., where refrigerant can stay, since
refrigerant is heavier than air.
R: Total Quantity of Charged Refrigerant (kg) = C: Refrigerant Concentration
V: Room Volume (m
3
) ≤ 0.3 (kg/m
3
)
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