The PHD-4 is able to detect very small leaks in objects that have a slight helium/air pressure inside. It is sensitive to helium concentrations as small as 2 ppm- equivalent to a leak rate of 5x 10-6 atm-cc/sec, far superior to the performance by other means of detecting leaks, such as bubble-testing. The PHD-4 sensitivity relies on Agilent’s proprietary and patented SIPD (Selective Ion Pump Detection) technology. Since it is controlled by a microprocessor, the PHD-4 is easy to use with no training required. All tuning and zeroing are handled automatically. The display can be set to use any of four languages (English, French, German, and Italian).