Caution On Refrigerant Leakage; Maximum Permissible Concentration Of Hcfc Gas; Calculation Of Refrigerant Concentration; Countermeasure For Refrigerant Leakage According To Khk Standard - Hitachi FSG1 Series Technical Catalogue

13.8. CAUTION ON REFRIGERANT LEAKAGE

Specifiers/installers have responsibility to follow local codes
and regulation which specify safety requirements against
refrigerant leakage
13.8.1. MAXIMUM PERMISSIBLE
CONCENTRATION OF HCFC GAS
The refrigerant R407C, charged in the SET-FREE FSG
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 0.3 kg/m³, 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 concentration in air below 0.3 kg/m³, in case of
leakage.
13.8.2. CALCULATION OF REFRIGERANT
CONCENTRATION
1. Calculate the total quantity of refrigerant R (kg) charged
in the system connecting all the indoor units of rooms to
be air-conditioned.
2. Calculate the room Volume V (m³) of each room.
3. Calculate the refrigerant concentration C (kg/m³) of the
room according to the following equation:
R: Total Quantity of Charged Refrigerant (kg)
R
V: Room Volume (m³)
— = C
C: Refrigerant Concentration (£0.31* kg/m³ for
V
R407C)
* Use this value for reference only, since this value is not
fixed yet.
System A Outdoor Unit
System A
Refrigerant: 35 kg
E D C
Floor Floor Floor
20 m² 40 m² 40 m²
Gas Leak Detector
Ventilator 2 m³/min
Room R (kg) V (m³)
A 30 150
B 65 500
C 35 100
D 35 100
C+D 35 200
E 35 50
REFRIGERANT PIPING AND REFRIGERANT CHARGE
System B Outdoor Unit
System B
Refrigerant: 30 kg
B A
Floor 200 m²
Floor 60 m²
Opening: 0.06 m²
C (kg/m³) Countermeasure
0.2 -
0.13 -
0.35 0.06 m² Opening
0.35 0.06 m² Opening
0.175 -
0.7 2 m³/min
13.8.3. COUNTERMEASURE FOR REFRIGERANT
LEAKAGE ACCORDING TO KHK
STANDARD
The facility shall be arranged as follows referring to the KHK
standards, so that the refrigerant concentration will be
bellow 0.3 kg/m³.
1. Provide a shutterless opening which will allow fresh air to
circulate into the room.
2. Provide a doorless opening of 0.15% or more size to the
floor area.
3. Provide a Ventilator, Linked with a gas leak detector, of
0.4 m³/min or more ventilating capacity per Japanese
Refrigeration Ton (=compressor displacement m³/h/8.5)
of the air conditioning system utilizing refrigerant).
O.U. Model Ton
RAS-5FSG 2.49
RAS-8FSG 4.32
RAS-10FSG 4.64
RAS-16FSG 6.69
RAS-20FSG 8.53
RAS-24FSG1 8.72
RAS-30FSG1 10.55
4. Pay a special attention to the place, such as a basement,
etc., where refrigerant can stay, since refrigerant is
heavier than air.
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O.U. Model Ton
– –
RAS-8FXG 3.74
RAS-10FXG 4.01
RAS-20FXG1 7.45
RAS-30FXG1 10.55