Simply converts standard air-cooled servers to liquid-cooled servers

KUL 2 is a sealed Precision Liquid Cooled chassis enclosure that simply converts standard air-cooled servers to liquid-cooled servers. With a few minor modifications – like removing the fans – off-the-shelf, air-cooled servers can be dropped into the KUL 2 chassis enabling them to be deployed as liquid-cooled servers.

The entire server is encapsulated inside the KUL 2 chassis where dielectric coolant is pumped through the in-chassis plate heat exchanger and precision delivered to CPUs, GPUs, memory and other critical components via an in-chassis manifold.

Sealed, secure and resilient in the most extreme locations

The KUL 2 liquid-cooled chassis provides unique value by completely isolating the critical IT from the environment with a perfectly sealed and resilient enclosure. This enables secure and tamper-proof computing, storage and networking, providing an extra level of physical and I/O connective security in the most extreme locations and climatic conditions.

Technology highlights

Sensor-rich environment

KUL 2 is a sensor-rich environment monitoring everything from fluid level, fluid temperatures and pressure, offering the ability to monitor server component sensors with the Advanced Management Out of Band Add In card.

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How does it work?

  1. KUL 2 offers a 3U sealed enclosure where the entire 19” server is encapsulated inside.
  2. The dielectric coolant is pumped through the in-chassis plate heat exchanger and precision delivered to CPUs, GPUs, memory and other critical components via an in-chassis manifold.
  3. Heat sinks are replaced with KUL Sinks on the CPUs and optimised cowling is used to integrate with the GPUs. Dielectric coolant is delivered to the KuUL Sinks and GPUs, which then overflows or spills into the chassis capturing the heat from all other components as it flows back through the chassis. This means there is no front-to-back air cooling and no bottom-to-top immersion constraints.
  4. Low-power, pumps create a gentle recirculating coolant flow inside the chassis enabling the heat to be returned to the in-chassis plate heat exchanger where it is transferred to the warm water heat rejection loop.
  5. Warm water enters the plate heat exchanger via the integrated fluid manifold at the back of the rack at up to 45°C (ASHRAE W4) and exits at up to 52°C. With these high operating temperatures chillers are typically not needed.
  6. Power in, signal out are passed through L2A (liquid-to-air) connectors which allows adaption from traditional air-cooled technology to a chassis-level liquid-cooled server design.

Varistar liquid-cooled rack system

KUL 2 comes fully integrated with nVent’s Varistar Liquid-Cooled Rack System. The system includes a dripless fluid manifold and zero-U PDUs with options for an In-Rack HRU, External Dry Cooler, In-Row HRU, CDU, UPS and advanced Out-of-Band Management offering complete control of the entire system remotely.

The 600mm Rack System comes in 24U and 48U variants and can accommodate up to 16 KUL 2 chassis per 48U rack.

Frequently asked questions

If you can not find the answer to your question here, please get in touch or download our Guide to KUL 2 below.

No, we use specially engineered dielectric coolants to collect the heat from the hot electronics.

Yes, in a good way. The coolant creates a protective environment for the servers, allowing them to perform better and last longer.

As the coolant creates a protective environment, the requirement for servicing is greatly reduced but should you be required to upgrade a component the process is very similar to that in an air-cooled chassis. Many components can be serviced like air-cooled servers, but system planar board replacement may require fluid to be drained. 

Yes, the coolant can be removed from the KUL 2 chassis while it is still supported in the cabinet if required.

Deionised water can be up to 45°C into the rack. This means that the TCS coolant does not need to be chilled.


Maintaining a maximum of 7°C delta T allows for useful heat reject temperatures while minimising the flow requirements of the water cooling loop.

The circuit uses de-ionised water with biocides and corrosion inhibitors.

Other than when using a dry cooler, a CDU is required to control tempterature, pressure, flow rate and quality of the de ionised water circuit and thus protect your equipment.

600mm wide x 1520mm deep x 2270mm tall (48U).
600mm/ 750mm wide x 1460mm deep x 1215mm tall (24U).

KUL 2 does not use fans for cooling, and the data hall does not need the air-handling equipment and hot-aisle/cold-aisle containment. Servers can be loaded more densely into each rack.

Manifolds are connected to the water coolant circuit using flexible hoses which are supplied with Eaton FD83 Series full flow dual interlock couplings.

ASHRAE (American Society of Heating, Refrigeration and Air-Conditioning Engineers) have published guidelines for both air-cooling and liquid-cooling of IT equipment in Data Centres. Setting a maximum allowable air input to the chassis is to ensure that the processors run as efficiently as possible and do not overheat. As air cooling is a lot less efficient than liquid cooling, the air-input temperatures need to be considerably lower than liquid-input temperatures for liquid cooling. We can achieve the same or better levels of cooling using  45°C liquid than with 27°C air.

Due to the high output temperature of KUL 2, the heat generated can be rejected via In-Rack HRU, External Dry Cooler, traditional CDU or In-Row HRU.

No, the water-based building-level cooling circuit only flows through the plate heat exchanger to pick up the heat from the dielectric coolant.

Monitoring of all system sensors is provided via the basic control system. An Advanced Monitoring Board is available which provides additional access to all server sensors.

Yes, the cooling system is flexible to accommodate different IT configurations. Our IO PCBs allow the chassis to be configured to provide IO ports that are appropriate to the IT.

Yes, KUL 2 is configured to have two power feeds as standard.

Yes, the power supply is liquid-cooled within the KUL 2 chassis.

Each KUL 2 chassis can cool up to 3.5kW of IT, dependent on flow rate and input temperature of the secondary-cooling circuit.

A Guide to KUL 2

Liquid cooling for off-the-shelf servers

Download brochure

Get in touch

Please contact us to arrange a demo or to find out more on how Precision Liquid Cooling is accelerating a sustainable, digital world.

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