Nitrogen Flow Indicator
Oxide scale on the inside of the pipes during the braze process. Refrigerant is a natural cleaning agent. When it is pumped through the copper tubing, it
will pick up scale that contaminates the refrigerant. This causes blockage and flow restriction in the TXV valve and possibly can cause damage to the compressor.
Flowing Nitrogen gas through the copper tubing while brazing will displace the Oxygen and prevent oxidation inside the tubing. How does one know that Nitrogen is actually flowing in the tubing? The Uniweld #UNF3 Nitrogen Flow Indicator is a visual tool that confirms the flow of Nitrogen gas through the copper lines during the brazing process. Nitrogen flow is confirmed when the float ball rises up in the flow indicator tube (see picture). If the float ball does not rise up in the tube, then there is static pressure and the Oxygen is not being displaced.