Application of BT8200 Cleanliness Testing Equipment in Cold Plate Liquid Cooling Systems

What is a cold plate liquid cooling system?

The cold plate liquid cooling system consists of a secondary cooling system, a primary cooling system, and a monitoring system. It transfers heat from components to a sealed coolant in the circulation pipeline through a cold plate, then distributes it via one or more cooling circuits, ultimately expelling the equipment's heat outdoors.

The secondary side cooling system consists of cooling medium, cold plate, quick-connect liquid fitting, distributor, secondary side piping, and cooling distribution unit. The primary side cooling system comprises cooling medium, primary side piping, outdoor cooling source equipment, and auxiliary devices.

Cleanliness test target for cold plate liquid cooling system

In cold plate liquid cooling systems, particle cleanliness detection is critical because small particle contaminants can clog microchannels (especially in cold plates), wear pump bearings and seals, reduce heat exchange efficiency, and even cause system failures.

This article introduces the components that need to be cleaned in the cold plate liquid cooling system.

Cold drawing ：

Reason: This is one of the key components. The microchannels inside the cooling plate (especially those used to cool the CPU/GPU) are extremely narrow (typically just a few tenths of a millimeter in diameter). Even very small particles (a few dozen microns) can clog these channels, causing localized overheating and component failure.

Check points: after manufacturing (welding, brazing, machining), before assembly, and after cleaning the whole system.

Heat exchanger ：

Reason: Whether it is a water-cooled liquid-water heat exchanger or a water-cooled liquid-air heat exchanger (radiator), the internal flow channel is relatively narrow (especially the plate heat exchanger). Particles will deposit on the flow channel or fins, reducing the heat transfer efficiency and increasing the flow resistance.

Check points: after manufacturing, before assembly, and after the entire system is cleaned.

Connector and joint:

Reason: It includes quick-connect connectors, flanges, threaded connectors, etc. The grooves, sealing ring installation grooves, threads and other parts inside are easy to retain machining chips or particles brought in during assembly. These particles will directly enter the main circulation under the scouring of fluid.

Check points: after manufacturing/mechanical processing, before assembly (especially in the sealing area).

Pipes/lines:

Reason: Contaminants may remain on the inner wall of the long straight pipe from manufacturing (such as bending, cutting) or storage. Although large diameter pipes are relatively less prone to blockage, particles will continue to contaminate the fluid and wear other parts.

Inspection points: after manufacturing/cutting/bending, before assembly (pay special attention to cutting end face burrs and internal cleaning).

Overall system loop:

Reason: After cleaning and assembling all parts, flushing the entire circuit and testing the particle concentration of the flushing fluid is the final step to confirm that the final cleanliness of the system meets the standard. This can detect contaminants introduced during assembly and possible "dead zone" residues.

Check point: after the system assembly is completed and the specified process is washed, before the working fluid is added.

In cold plate liquid cooling systems, all components in direct contact with the coolant must undergo particle cleanliness testing during manufacturing and final assembly. This is particularly critical for parts with narrow flow channels, precision moving components, or prone to contamination buildup (e.g., cold plates, heat exchangers, manifold distributors, and UQD quick connectors). System-level final rinse fluid cleanliness testing serves as the final critical checkpoint for ensuring reliable operation. Strict cleanliness control forms the foundation for maintaining high performance, extended service life, and operational reliability in liquid cooling systems.

Cleanliness detection method for cold plate liquid cooling system

Particle counting is a quantitative and high-precision detection method used to determine the size distribution and concentration of solid particles in liquid samples or contaminants extracted from component surfaces. It is the core technology for evaluating the cleanliness of liquid cooling systems.

The particle counting method operates on the principle of photoresist technology, where a liquid sample flows through a narrow, light-illuminated channel. As particles pass through the liquid, they block the light, causing a sudden decrease in the sensor's light intensity. This intensity change is captured by a photoelectric sensor and converted into an electrical pulse signal. The pulse amplitude is directly proportional to the particle's projected area (i.e., particle size). Through calibration, the instrument converts the pulse amplitude into the particle's equivalent diameter (typically based on a standard sphere's diameter). Each counted pulse signal represents one particle.

The particle counting method has the advantages of fast detection, high accuracy and the ability to obtain the number of particles in multiple size channels at the same time. It is the mainstream method at present. The disadvantage is that it cannot distinguish the material and shape of particles.

Application of BT8200 Cleanliness Testing Equipment in Cold Plate Liquid Cooling Systems

The Bebur BT8200 particle detection system employs photoresist detection technology to monitor particle size and quantity across eight channels simultaneously. With reliable performance and user-friendly operation, it meets diverse industrial needs and is widely used in liquid cooling systems, hydraulic systems, component cleaning, casting machinery, pharmaceuticals, electronics, and related fields.

For cold plate liquid cooling systems, particle counting serves as a critical quality control measure to evaluate reliability and service life. Utilizing principles like the photoresist method, this technique precisely quantifies contaminant levels, providing indisputable data for design, manufacturing, and maintenance. Strictly controlling particulate contamination is paramount to ensure efficient and stable operation of liquid cooling systems, particularly those involving microchannel cold plates.