DC Inverter U-match Series Floor Ceiling Type Unit 
27 
And verify if the pressure gauge at the low pressure side of the manifold valve 
assembly  reads  -1.0Mp  (-75cmHg), if  not,  it  indicates there  is leak  somewhere. 
Then, close the switch fully and then stop the vacuum pump.   
(6)  Wait for 10min to see if the system pressure can remain unchanged. During this 
time, the reading of the pressure gauge at the low pressure side can not be 
larger than 0.005Mp (0.38cmHg). 
(7)  Slightly open the liquid valve and let some refrigerant go to the connection pipe 
to balance the pressure inside and outside of the connection pipe, so that air will 
not come into the connection pipe when removing the hose. Note that the gas 
and liquid valve can be opened fully only after the manifold valve assembly is 
removed. 
(8)  Place back the caps of the liquid valve, gas valve and also the service port. 
 
Notice: 
For large-size units, there are maintenance ports for liquid valve and gas valve. 
During evacuation, you may connect the two hoses of the branch valve assembly to 
the maintenance ports to speed up the evacuation.   
3.2.4.2 Leak Detection Methods 
The  following  leak  detection  methods  are  deemed  acceptable  for  systems 
containing flammable refrigerants. 
Electronic leak detectors shall be used to detect flammable refrigerants, but the 
sensitivity may not be adequate, or may need re-calibration. (Detection equipment 
shall be calibrated in a refrigerant-free area).