Due to its nontoxic and nonflammable properties, helium is often used in leak detection for production quality control. Helium leak testing is nondestructive, more sensitive, and faster than bubble testing. Unlike pressure decay, it also allows users to pinpoint the location of a leak. Pfeiffer Vacuum (Nashua, NH, U.S.; www.pfeiffer-vacuum.com) says it has further improved the helium leak testing with its SmartTest system. “It features the world’s highest sensitivity at 5 × 10-12 mbar l/s, and is the only leak detector to feature a turbopump that makes use of a magnetic bearing on the high vacuum side to eliminate contamination of the ion source,” says Steve Blair, product manager, leak detection and gauges.

Based on a modular design, the helium leak detector allows users to choose from a variety of configurations that best suit their applications. A rotary vane pump is used for general leak detection, while a dry pump is suited for absolutely oil-free application. The bypass option is available for fast leak detection when testing large, contaminated items.

According to Blair, one feature that appliance manufacturing engineers would find most beneficial is the HLT572’s XtraDry backing pump. “This dry pump’s ability to resist backstreaming of light gasses makes it ideal for helium and hydrogen mass spectrometer leak detection,” Blair says. “The pump features two independent compression chambers that provide a mechanical barrier to any gasses that try to enter via the exhaust stage. This proprietary Pfeiffer Vacuum technology eliminates all backstreaming which is a major issue with scroll, dry membrane and rotary vane pumps.”

Depending on the nature of the items to be tested, users can choose either integral and local leak detection. The former method measures the total leak rate in smaller test items with a short cycle time. It provides a clear go/no-go indication with high objective measurement accuracy. The latter approach is used for precise localization of the leak site in large test items. It identifies the exact magnitude of the leak, helping to locate repetitive production defects.

Blair says refrigeration condenser coils are commonly leak checked using the SmartTest leak detector. “The high sensitivity and leak rate data reporting enabled by the output features of the leak detector can allow a manufacturing facility to perform quality control prior to parts reaching final assembly. This can lead to greater efficiency by reducing downtime and rework, resulting in overall higher quality.”

The unit comes with features such as built-in vacuum and sniffing modes, an internal calibrated leak, three flow modes, the highest test pressure, as well as the ability to detect helium and hydrogen.