Caution Of The Pressure By Check Joint - Hitachi 3HRNM1Q Installation & Maintenance Manual

5.6

Caution of the Pressure by Check Joint

When the pressure is measured, use the check joint of gas stop valve ((A) in the figure below) and use the
check joint of liquid piping ((B) in the figure below).
At that time, connect the pressure gauge according to the following table because of high pressure side and
low pressure side changes by operation mode.
Check Joint for Gas Stop Valve "A"
Check Joint for Piping "B"
Check Joint for Liquid Stop Valve "C"
NOTE:
Be careful that refrigerant and oil do not splash to the electrical parts when removing the charge hoses.
1. Maximum Permissible Concentration of HFC GAS R410A ,R410A 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, R410A in air is 0.3kg/m
standard (KHK S 0010) by the KHK (High Pressure Gas Protection Association) Japan. Therefore, some
effective measure must be taken to lower the R410A concentration in air below 0.3kg/m
2. Calculation of Refrigerant Concentration
(1) Calculate the total quantity of refrigerant R (kg) charged in the system connecting all the indoor units of
objective rooms.
(2) Calculate the room volume V (m
(3) Calculate the refrigerant concentration C (kg/m
R: Total Quantity of Charged Refrigerant (kg)
V: Room Volume (m
If local codes or regulations are specified, follow them.
Cooling Operation
Low Pressure
High Pressure
Exclusive for Vacuum Pump and Refrigerant Charge
3 , according to the refrigeration and air conditioning facility
3
) of each objective room.
3 ) of the room according to the following equation.
= C: Refrigerant Concentration
3 )
16
Heating Operation
High Pressure
Low Pressure
3
, in case of leakage.
≤
0.3 (kg/m 3 )