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Double-Pipe Condenser Refrigerant/Water Cross-Leakage (Pressure Test Identification)

Likely causes

Pinhole corrosion in inner tube

Check: refrigerant (high pressure, 1.5~2.5 MPa) leaks into water side

What to do: Determine leak direction: pressurize refrigerant side with N2 to 1.2 MPa, isolate water side → if water-side pressure rises, leak is from refrigerant to water

Fatigue cracking at U-bend hairpin weld

Check: bidirectional refrigerant/water mixing

What to do: Check reverse direction: pressurize water side to 0.6 MPa + monitor refrigerant-side pressure gauge → confirm water-to-refrigerant direction

Water-side pressure exceeds refrigerant-side pressure (pump overpressure > 0.8 MPa)

Check: moisture infiltrates refrigerant circuit

What to do: Locate leak: inject N2 into each loop separately + bubble test (focus on hairpin weld joints)

Scale on inner tube outer surface reduces heat transfer

Check: localized overheating → tube wall degradation

What to do: Replace inner tube: use same specification or SUS316L stainless inner tube; perform X-ray inspection of welds before use

Vibration/pulsation loosens fittings

Check: gap leakage

What to do: Install water-side pressure regulator: limit pump outlet to ≤ 0.5 MPa to prevent pressure reversal into refrigerant circuit

Field tip

Always pressurize the lower-pressure side first before start-up — pressure reversal rapidly expands pinholes.

All 565 cases work offline in R-Pro, with error codes for 62 brands and P-T data for 108 refrigerants.

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