Hitachi RAS-10HRNM, Service Manual, Page: 472 / 482

12.7 Caution with the refrigerant leakage
The designers and the installers have the responsibility to follow the local codes and the local regulations that specify the
safety requirement against the refrigerant leakage.
12.7.1 Maximum permissible concentration of the HCFC gas
The refrigerant R410A, which is charged in the UTOPIA IVX/ES system, is an incombustible non-toxic gas. However, if the
leakage occurs and the gas fills a room, the gas may cause suffocation.
The maximum permissible concentration of the HCFC gas and the R410A in the air is 0.44 kg/m
³
, according to the
refrigeration and air conditioning system standard (KHK S 0010) by the KHK (high-pressure gas protection association) of
Japan. Therefore, you must take some effective measures in order to lower the R410A concentration in the air below 0.44
kg/m
3
, if there is a leakage.
12.7.2 Calculation of the refrigerant concentration
1 Calculate the total quantity of refrigerant R (kg) that is charged in the system that connects all the indoor units of the
rooms that need air conditioning systems.
2 Calculate the room volume V (m
³
) of each room.
3 Calculate the refrigerant concentration C (kg/m
³
) of the room according to the following equation:
C = R/V
R: Total quantity of charged refrigerant (kg)
V: Room volume (m
³
)
C: Refrigerant concentration (
≤
0.44* kg/m
3
for the R410A)
* Use this value only for reference because this value is not fixed yet.
12.7.3 Countermeasure for the refrigerant leakage according to the KHK standard
According to the KHK standards, you should arrange the facility as follows so that the refrigerant concentration will be bellow
0.3 kg/m
3
.
1 Provide a shutterless opening that will allow the fresh air to circulate into the room.
2 Provide a doorless opening with a size of 0.15% or more to the floor area.
3 Provide a ventilator, which must be linked with a gas leak detector, with a ventilating capacity of 0.5 m
3
/min or more per
Japanese refrigeration ton (=compressor displacement 8.5 m
3
/h of the air conditioning system which uses the
refrigerant).
•
IVX
O.U. model Ton
RAS-8HRNM 2.49
RAS-10HRNM 3.32
RAS-12HRNM 4.15
• ES
O.U. model Ton
RAS-(2-2.5)HVRN1(E) 0.88
RAS-3HVRNS 1.14
RAS-4HVRNS1E 1.67
RAS-(5-6)HVRNS1E 2.27
RAS-8HRNSE 2.49
RAS-10HRNSE 3.32
4 Pay a special attention to the place, such as a basement and others, where the refrigerant may stay, because the
refrigerant is heavier than the air.
12 Maintenace notes
464
SMGB0060 rev. 1- 12/2010