Patent ID: 8291748

Claim:
A method for detecting a leak between separate first and second fluid paths of a heat exchanger arranged in heat exchange relationship, the method comprising: sealing a test section including said first and second fluid paths wherein said test section has first and second ends; evacuating said first and second fluid paths; introducing a test gas to said first fluid path so that a pressure differential is created between said first fluid path and said second fluid path, wherein said first and second fluid paths are each evacuated to a substantially sub-atmospheric pressure prior to introducing said test gas to said first fluid path; and testing for the presence of said test gas in said second fluid path whereby the presence of a leak between said first and second fluid paths of said test section may be determined, wherein said second fluid path is evacuated at or near to one end of said test section and said test gas is introduced at or near to the other end of said test section within said first fluid path.