In the manufacturing and maintenance of LiBr absorption units, vacuum level is the core factor determining unit performance and service life. Even minor leaks allow air to enter the unit, which reduces the unit's energy efficiency and causes corrosion. Therefore, sealing integrity inspection is crucial. Helium detection usually includes positive pressure helium detection and negative pressure helium detection.

Positive Pressure Helium Detection: Used for preliminary screening of unit vacuum integrity. The unit is filled with nitrogen to micro-positive pressure. Soapy liquid is then applied to the weld seams. If there is no bubbles , it means qualified. If a leak exists, escaping nitrogen will produce visible bubbles at that location.Negative Pressure Helium Detection: Offers extremely high sensitivity and precise localization capabilities.

The method is divided into two types:

  1. Spray Method: The unit is first evacuated to vacuum. Then, a helium spray gun is used to spray helium at suspected external leak points. If a leak exists, helium will be drawn into the unit by the negative pressure.

  2. Helium Cover: A specially designed cover completely encloses the entire unit, and the cover is filled with a certain concentration of helium. If any leak exists in the unit, helium will be drawn into the unit.

In both negative pressure detection methods described above, the core instrument is the helium leakage detector connected to the vacuum system. It can sensitively detect trace amounts of helium drawn inside. Therefore, negative pressure helium detection is more precise and rigorous.

Through this meticulous helium detection process that LiBr absorption units possess excellent vacuum, fundamentally guaranteeing the long-term efficiency and stable operation of the equipment.