DC Inverter U-match Series Duct Type Unit 
 
the refrigerant used. Leak detection equipment shall be set at a percentage of the 
LFL of the refrigerant and shall be calibrated to the refrigerant employed and the 
appropriate percentage of gas (25% maximum) is confirmed. 
Leak detection fluids are suitable for use with most refrigerants but the use of 
detergents containing chlorine shall be avoided as the chlorine may react with the 
refrigerant and corrode the copper pipe-work. 
If a leak is suspected, all naked flames shall be removed / extinguished. If a 
leakage of refrigerant is found which requires brazing, all of the refrigerant shall be 
recovered from the system, or isolated (by means of shut off valves) in a part of the 
system  remote from the leak. Oxygen free nitrogen (OFN) shall then be purged 
through the system both before and during the brazing process. 
3.2.5 Refrigerant Adding 
NOTE! 
Before and during operation, use an appropriate  refrigerant leak detector to 
monitor the operation area and make sure the technicians can be well aware of 
any potential or actual leakage of inflammable gas. Make sure the leak detecting 
device is applicable to inflammable refrigerant. For example, it should be free of 
sparks, completely sealed and safe in nature.   
See the following table for the amount of additional refrigerant. 
 Item 
Model 
Standard 
Pipe Length   
Unnecessary 
Charge Pipe 
Additional 
Refrigerant Amount 
GUD35W/NhA-T 
5.0m  ≤7.0m   
16 g/m   
GUD85W/NhA-T  30 g/m 
35 g/m 
7.5m  ≤ 9.5m    40 g/m