Caution In Case Of Refrigerant Leakage; Maximum Permitted Concentration Of Hfcs; Calculation Of Refrigerant Concentration; Countermeasure For Refrigerant Leakage - Hitachi RASC-4HNPE Service Manual

3 Piping work and refrigerant charge

Caution in case of refrigerant leakage

3.5 Caution in case of refrigerant leakage
The installers and those responsible for drafting the specifications are obliged to comply with local safety codes and
regulations in the case of refrigerant leakage.

3.5.1 Maximum permitted concentration of HFCs

The refrigerant R410A, charged in the RASC series 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 HFC gas, R410A in air is 0.44 kg/m³, according to EN378-1.
Therefore, some effective measure must be taken to lower the R410A concentration in air below 0.44 kg/ m³, in case of
leakage.

3.5.2 Calculation of refrigerant concentration

1 Calculate the total quantity of refrigerant R (kg) charged in the system by connecting all the indoor units in the 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:
C= R / V

3.5.3 Countermeasure for refrigerant leakage

The facility must have the following features in case of a refrigerant leakage occurs:
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 There must be a ventilator fan connected to a gas leak detector, with a ventilator capacity of 0.4 m³/min or higher per
Japanese refrigeration ton (= compressor displacement volume / 5.7m³/h) of the air conditioning system using the
refrigerant.
4 Pay a special attention to the place, such as a basement, etc., where refrigerant can stay, since refrigerant is heavier
than air.
(See the example of the following page)
52 SMGB0091 rev.2 - 11/2015
R: Total quantity of refrigerant charged (kg)
V: Room volume (m³)
C: Refrigerant concentration (=0.44* kg/m³ for R410A)
Model
RASC-(4-6)HNPE
RASC-8HNPE
RASC-10HNPE
Tonnes
2.27
3.16
4.11