In-Line Leak testing: Advanced industrial solution for appliances

Marposs Solutions is focused on developing the best leak-testing performance for more efficient products to improve HVAC energy efficiency. Leak testing is fundamental in all thermal exchange processes using refrigerant gases. It ensures the long-term tightness of refrigerant-containing components.

In the context of the White Goods/Home Appliances industry, the Marposs Dryer Heat Pump Leak Test application is a high-tech end-of-line test that allows the manufacturer to guarantee very high quality in its final product – without sacrificing the high productivity it must maintain to meet market demand with actual production sites. With this solution, the vacuum helium leak detection system applied to the entire finished assembly provides the most reliable method of detecting global leakage on the circuits.

The testing method includes the tracer gas Helium 100%, and the analysis system involves a mass spectrometer measurement in a vacuum chamber. This method is the most powerful among the various leak-testing systems, aiming to detect the smallest quantity of leak values.

In-Line leak testing

Marposs in-line leak test machines test the heat pump assembly with a 10-5 mbar*l/s range leak threshold. For a better evaluation, compare this with a traditional nitrogen leak test in a water tank, which gives results estimated in the range of 10-2 mbar*l/s (one bubble with a radius of 2 mm in 1 second), but taking into account the human guesswork and then include undetected bubbles/leaks.

The large manufacturing tolerance in all directions for the coolant tubes represents a critical issue for automatic testing. To overcome this, Marposs developed a very flexible coupling design. It allows the inlet pipe to be connected automatically despite the high uncertainty of positioning in the assembly. The coupler has a large compensating capacity, even when a large distance is covered up and down to reach the connection point with vertical pneumatic movement. A highly applicable manual test has been realised as a fully automatic test with enormous benefits for production.

The modular solution (from 1 to several leak test stations) offers a wide range of productivity in fully automated production.

Leak testing

Leak testing is fundamental in all thermal exchange processes using refrigerant gases. It ensures the long-term tightness of refrigerant-containing components and guarantees performance in the case of heat exchange efficiency. The increasing demand for energy-efficient heat exchange systems is one of the main drivers of high-accuracy leak testing of HVAC products.

Only leak-testing technologies that facilitate this will be more precise and dependable in the context of temperature control and, eventually, the growing focus on the possible role of refrigerant compounds in global warming.

In addition, to ensure accuracy, a leak test solution must be used, and all parts and circuit connections must be guaranteed to comply with a total leakage lower than that permitted by law (specific thresholds for each chemical compound). That is why the components and the final assembly must undergo this EOL leak test.

Leak detection is essential to ensure the thermal assembly performs efficiently after installation. It confirms that the heat exchange efficiency will remain stable over a reasonable warranty period.

This remains true until the use and consumption of the parts are subject to significant use and wear.

Leak testing solutions by Marposs

Marposs Solutions is developing the best leak-testing performance for more efficient products. The vacuum test chamber method also provides some additional tests that complete and add value to the test station.

A basic test is the standard preliminary gross leak test carried out on the dryer heat pump assembly using the air pressure decay technique. In the event of a defect on a part, eliminating the fine leak test on NG parts achieves valuable advantages, thus saving time and simultaneously providing quality data management for production process adjustment.

The second basic test available is the manual sniffing system always fitted to Marposs HLT vacuum machines to enable maintenance, troubleshooting and repositioning of leaks for corrective action in the production processes. Other cases are additional functional tests performed in the same test station for electro-pneumatic devices in the unit. Full test traceability functions for manufacturer-to-end user warranty purposes.

Marposs can provide the helium recovery system with a high efficiency (85-95%). The system is connected to the leak test machines, recovering the helium used for each test cycle and recycling it to feed the leak test machines again in a closed system. Helium purity is analysed and, if necessary, corrected by refilling and final compression of the stored helium to the required test pressure. The recovery output provides leak test set points to the HLT machines so that data outside the acceptable range generates alarms to avoid false leak detection. With the fastest return on investment, the fully integrated process improves the system’s accuracy and reliability.

For more info, visit: www.marposs.com