About CTMA

Projects
- emerging
- active
- completed

Services
- LPDI
- Technology Roadmapping

Newsletter
- current

- past issues

- subscribe

Web Links
- DoD Sites
- DoD Facilities
- related sites

Join NCMS

Past Symposiums

Submit Project Ideas

Site Map

NCMS
Homepage
 

Leak Test Technologies

Current state-of-the-art leak detection in industrial and military production communities uses helium mass spectrometry to detect leaks in products or components with sensitivity capability up to 10^-11 standard cubic centimeters per second (sccs). However, sensitivity levels predominantly sought in industrial and military production applications range from 10^-2 to 10^-6 sccs.

Typically, vacuum–helium mass spectrometry is used on-line to detect and quantify cumulative leak rates within this range. Then, a second stage operation at a reject station is needed to isolate and locate the leak site or sites on the product. Once at the reject station, the part is typically re­pressurized to the requisite psi and subjected to testing by immersion in water or other liquid in a dunk tank. This process has sensitivity in the 10^-2 sccs range leaks. A single leak site having a leak rate volume at 2 x 10^-6 sccs would take over 135 min in a dunk tank to form one bubble. Lar­ger products, where total immersion is not practi­cal, are typically subjected to pressurization/soap­ing for leak location. This bubble detection methodology has all the same limitations as does total immersion, low sensitivity and total depen­dence upon operator diligence and acuity.

Today’s process results in either many parts being scrapped because the leak location cannot be found at the reject station and marked for repair, or by low detection sensitivity methods, like immersion and soaping, which allow many parts with latent leaks to pass into final assembly.

In January 1999, Leak Test Prototype Develop­ment & Prove-Out was funded jointly by the Office of Secretary of Defense (OSD) and the industrial partners in the National Center for Manufacturing Sciences (NCMS) Leak Test Technology Development (LTTD) Consortium. Prototype technologies were built and tested for NCMS member industrial applications and for defense depot applications at Jacksonville Naval Aviation Depot (JAX).

Three technologies advanced out of research done earlier by the LTTD Consortium: speed of sound (SoS) sensor, a derivative of surface acoustic wave (SAW) research work, photo­acoustics (PA), and millimeter wave (MMW). The SoS sensor and MMW were targeted for prove-out on applications at JAX in addition to industrial applications. Argonne National Laboratory (ANL) was to build the prototypes with assistance of Vacuum Instrument Corporation (VIC). A PA prototype was to be built by VIC for targeted applications in the ground transportation industry and weapons manufac­turing at Honeywell Federal Manufacturing & Technologies, the Department of Energy’s Kansas City Plant (KCP).
 

Program Manager: Connie Philips, (734) 995-7051, conniep@ncms.org