What is a UQD coupling in liquid cooling?

The Universal Quick Disconnect — a family of quick-release coolant couplings standardized by the Open Compute Project. Compliant plugs and sockets from different vendors interoperate and close dripless on disconnect, so servers, manifolds and CDUs can be mixed across the open ecosystem instead of being welded to one supplier.

Which UQD size do I need?

Match the nominal flow to your loop: single CPU cold plates typically use UQD04-UQD06, high-power GPU plate pairs UQD08-UQD12, dense node loops UQD16-UQD22, and rack manifold or CDU header feeds UQD32-UQD40. The size number approximates nominal L/min; always verify the vendor’s pressure-drop curve at your actual flow and fluid temperature.

Reference · 2 min read

UQD quick disconnects

UQD (Universal Quick Disconnect) is the OCP-standardized family of dripless coolant couplings: any compliant plug meets any compliant socket across vendors. Sizes run UQD04 → UQD40, where the number ≈ nominal flow in L/min — a per-plate loop typically uses UQD06–UQD12, rack manifolds aggregate to UQD32/UQD40 territory.

Macro photograph of dripless quick-disconnect coolant couplings — **PLATE 1** — Dripless quick disconnects up close: the valved halves that close on separation. AI-generated illustration (Z-Image Turbo) — representative, not a specific product.

The size table

Size	Nominal flow	Typical use
UQD04 / UQD06	≈ 4 / 6 L/min	Single cold plate loops (CPU plates, entry nodes)
UQD08 / UQD12	≈ 8 / 12 L/min	High-power GPU plate pairs, accelerator nodes
UQD16 / UQD22	≈ 16 / 22 L/min	Multi-plate node loops, dense 1U twins
UQD32 / UQD40	≈ 32 / 40 L/min	Rack-level manifold feeds, CDU headers

FIG. 1 — The OCP UQD family. Nominal flow ≈ the size number in L/min; check each vendor's pressure-drop curve at your flow before committing (pressure drop).

Why it matters

Interoperability. Standardized bodies and seals mean cold plates, manifolds and CDUs from different vendors mate — the open-ecosystem defense against lock-in (liquid-ready servers).
Dripless disconnects. Valves close on separation, spilling at most a film of residue — the difference between a serviceable rack and a hazmat event (leak design).
Blind-mate option. Combined with ORv3 manifolds, servers connect by sliding in — no hand-plumbing per node (how the loop fits together).
Size honestly. An undersized UQD is the highest-pressure-drop element in a sub-loop; check the curve, not just the mating chart.

Standards overview · Pressure drop · Coolant flow rate · Glossary

Sources

OCP Cooling Environments / UQD specification family (opencompute.org). Nominal flows are the size-class ratings; exact curves are per vendor and per fluid temperature — request them in the RFQ (RFQ checklist).

UQD quick disconnects

The size table

Why it matters

Related

Sources