Ten leak points every liquid-cooling team should know.
Not a ranking. A checklist, following the coolant from chip to facility. For each of the ten, a turnover package should answer: was it tested, against what acceptance criteria, and where is the record.
Definition
The ten leak points (ten leak points · 十大漏点) are the ten places a liquid-cooling loop can leak, listed in the order the coolant travels from chip to facility: cold-plate joints, quick disconnects, hose crimps, manifold branches, elastomeric seals, threaded and compression fittings, CDU internal boundaries, field welds, balancing and isolation valves, and fill, drain, vent and sample ports. For each, a turnover package should say whether it was tested, against which criterion, and where the record is.
By Jim Li, first published September 2026. The list discusses practices, not specific vendors or products.
Score your last projectAt the server
Cold plate joints
Brazed seams, friction-stir welds, covers and ports. Voids, incomplete bonding and microcracks sit upstream of the smallest flow passages.
Quick disconnects
Often the highest-count removable connection in the rack. A disconnected QD is not automatically a sealed one. One particle on the poppet seat may be enough.
→ First-fill cleanliness is leak prevention, not housekeeping.
Hose crimps
Crimp dimensions, concentricity, hose variation and material relaxation all matter. Once the sleeve is on, most defects are invisible.
→ A crimp is a controlled manufacturing process, not an assembly step.
In the rack
Manifold branches
Every server connection adds another boundary, and every server replacement disturbs it again.
Elastomeric seals
They sit inside QDs, valves, adapters and manifolds. Compression set, hardening, temperature and fluid incompatibility can turn a dry joint into a future leak.
→ "Compatible with water" is not a material specification.
Threaded, compression and adapter fittings
Preparation, alignment, support and torque all matter.
→ Looking dry at commissioning is not evidence of how a fitting was assembled or tested.
In the CDU
Internal boundaries
Pump seals, heat-exchanger gaskets, valve stems, filter housings and service covers. All enclosed, so a small leak may remain hidden until it reaches the cabinet floor or a sensor.
Between the CDU and the facility
Field welds and hot work
A weld is both a pressure boundary and a water-chemistry event.
→ Flushing removes transportable debris. It does not, by itself, passivate.
Balancing and isolation valves
Bodies, stems, unions and serviceable closures. Several boundaries at every location, operated during commissioning and then largely left alone.
Fill, drain, vent and sample ports
Small connections, frequently disturbed: temporary hoses connected and removed, caps replaced, valves reopened.
The point is not that factory joints never leak. It is that a boundary made under controlled conditions can be tested, recorded and released against defined acceptance criteria. A boundary made in a live hall at 2 a.m. deserves exactly the same evidence.
Against your own project, how many of the ten have a record you can produce?
Questions this page answers
What records should a liquid-cooled room hand over at turnover?
At minimum, an answer to three questions for each of the ten leak points: was it tested, against what acceptance criterion, and where is the record. Add IT and facility sub-metering, supply and return temperature and flow per loop, the CDU approach at a stated load, and the isolation-procedure test record. The turnover package →
Are the ten leak points a ranking?
No. They are listed in the order the coolant travels from chip to facility, so a commissioning team can walk the path and score each one. Which point matters most on a given site depends on how often it is disturbed: quick disconnects and manifold branches are touched at every server swap, field welds usually only once. Score your last project →
Which leak point is disturbed most often?
Quick disconnects, because they are the highest-count removable joint in the rack and are separated every time a server is replaced. A disconnected quick disconnect is not automatically a sealed one, so each mate and de-mate after fill belongs in the connection log. Why commissioning is its own clock →