Interconnection


Figure 3: A typical flow-rate plot shows the relation- ship between flow rate and pressure difference across the disconnect for the four connector sizes UQDB02 through UQDB08. (Image source: Amphenol)


Figure 6: The UQDLS-02HSH01-L000 socket has an integral release button and a red identifica- tion marker. (Image source: Amphenol)


series are rated to working pressures of 0 to 87 pounds per square inch (PSI) (0 to 0.6 megapascals (MPa)). They can sustain a maximum safe pressure of 290 PSI (2.0 MPa) and operate over a temperature range of -40°C to +105°C. For example, the UQDBP- 02TMU01-N000 (Figure 2) is an OCP-compliant (revision 1.0) UQDB02 plug with an external UNF 7/16-20 threaded stud for termination, and uses O-ring seals. Pressure in a liquid cooling system is analogous to voltage in an electrical circuit. Flow rate is the equivalent of current. The flow rate is described by the flow coefficient (Cv); the higher the Cv, the greater the flow capacity. The Amphenol UQDB02/04/06/08 disconnects have Cv values of 0.4, 1.32, 2.11, and 3.83, respectively.


A flow-rate curve plots pressure across the disconnect as a function of the flow rate (Figure 3).


Given that the flow rate increases proportionally with the connector diameter, the required flow rate determines the device selected. Note that the pressure across the disconnect increases with an increasing flow rate. Of concern in electronic applications is minimizing the presence of liquids in the environment. With this in mind, the QDs also specify fluid


loss upon disconnecting. The Amphenol


Figure 5: The UQDS-02HSH01-L000 is an example of a UQD02 socket with a hose barb termination and blue identification rings indicating it carries cold coolant. (Image source: Amphenol)


pair with larger hose barbs to maintain appropriate flow rates.


The identification bands, as mentioned earlier, mark the connector as carrying cold or hot coolant. The sockets are


also available with a


release button, as in the UQDLS- 02HSH01-L000 (Figure 6).


blind mate socket with a UNF 9/16“-18 thread.


UQDB02/04/06/08


connectors have fluid loss specifications of 0.004, 0.004, 0.006, and 0.01 millilitres (ml), respectively.


Figure 4: The UQDBS-02TMU02-N000 is a blind mate socket with a UNF 9/16”-18 thread. (Image source: Amphenol)


www.cieonline.co.uk


The other half of the QD connector pair is the UQDBS-02TMU02-N000 (Figure 4)


The UQD/UQDB series employs a push-to-connect latching mechanism that ensures secure, leak-resistant connections between cooling system elements. The UQDB02 plug mates with this socket with a mating force of 49 newtons (N) (10.6 pounds force) at zero pressure. The mating force increases with increasing connector diameter (58 N, 60 N, and 68 N for UQDB04/06/08, respectively). Another alternative termination is a hose barb for coupling a hose to the socket, as used in the UQDS- 02HSH01-L000 (Figure 5).


A hose allows greater flexibility in connecting the elements of a cooling system. The hose barb accepts a hose with an internal diameter (ID) of 1/4 inch (in.). Larger connector sizes in the series


The release button makes it easier to disconnect the mated plug and socket. The push-button latch socket features a flat- design button that does not extend beyond the body of the connector, making it easily accessible in confined quarters. This socket is also terminated in a 1/4 in. hose barb and includes a red identification band.


Conclusion


AI data centres are increasingly characterized by high power density with modular liquid cooling systems. These systems require sealed, dry-break liquid disconnects in multiple sizes and termination options for safe, reliable cooling in confined spaces. The Amphenol OCP-compatible UQD and UQDB solutions meet these needs to support continuous use in environmentally demanding electronics applications.


https://www.digikey.co.uk/ Components in Electronics September 2026 39


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