Gas and Chemical Sensors / Detectors
INFICON Offers Wide Array of Solutions for Pinpointing Leaks
DETROIT - New hydrogen-based leak-detection technology is helping automakers and their suppliers reduce costs and improve quality.
More than 1,000 leak tests are performed on the average car and its components before a vehicle rolls off a final assembly line and into a new-car showroom. Fuel, brake and other critical safety systems are tested multiple times for leaks, as well as driveline components, fluid containers and wheels.
More and more of these tests are conducted with hydrogen-based leak detectors, less expensive than helium-based systems and significantly better than more traditional water and pressure-decay methods.
The early detection of even the smallest leak with a hydrogen sensor can play a key role in reducing costs and improving customer satisfaction, according to Thomas Parker, the North American automotive sales manager for INFICON, a leading global supplier of leak-detection systems.
The sooner a leak can be identified the quicker it can be fixed or eliminated through improvements to the manufacturing process, Parker says.
"An automaker or its suppliers may know that an individual engine or transmission has a leak, but finding that proverbial needle in a system's haystack is the real challenge," notes Parker. "Our Sensistor Sentrac is one solution for quickly pinpointing a leak. It uses a maintenance-free microelectronic sensor that can focus 100 percent on detecting a safe hydrogen mixture that is injected into a component."
Most manufacturers use basic air testing, also known as a pressure-decay test, to leak check engines and transmissions on a pass-fail basis. A more sophisticated helium or hydrogen "tracer" gas must then be used to pinpoint actual leak locations, although some manufacturers still use out-of-date water tests.Â
Engines, for example, often are pressure-tested on a pass-fail basis. Each subsystem -- oil, coolant and emissions -- is pressurized simultaneously at a test station. (Permissible leak rates may vary from 0.05-10.00 SCCM at pressures from 100-500 kPa depending on the test circuit.) In case of failure, each component then will need to be retested with tracer gas to identify exact leak locations.
Parker estimates that leaks requiring fixes or repairs are found on more than 25 percent of the engines and transmissions annually produced for cars, light trucks and commercial vehicles sold in North America.
Based in Redford, Mich., TrigTec is a company that recently introduced INFICON technology to improve engine and transmission testing. TrigTec provides test products on a global basis for powertrain and vehicle-assembly operations.
"In an effort to eliminate water testing and replace a less effective performing hydrogen leak tester, we decided to utilize INFICON's hydrogen-based technology last year," said Steve Kravis, TrigTec's owner and president. "Our Sensistor Sentrac leak detector provides much more accurate test results. Leaks can be detected more quickly and sniffer recovery times after pinpointing a leak are much shorter as well."
Wet testing also could be used to pinpoint leaks, but is considered out-of-date. The time required to visually locate "leak bubbles" created by a specialized soap and water mix, for example, would be excessive in today's rapid production environment.
There are a variety of other downsides to wet testing. Using a soap-and-water solution to coat an engine, then waiting for bubbles to form might take hours. It also requires line-of-sight visual verification. Large leaks also can blow away bubbles and cause a leak to be overlooked.
In addition, Parker points out that there is no way to reliably quantify leaks using soap bubbles. And water-soap solutions can lead to unsafe work conditions that can result in slip-and-fall accidents. Submerging a transmission or engine in a soap-and-water solution also can damage electrical sensors and cause rusting that might affect warranty costs.
Parker adds that many manufacturers are moving to a "no liquid policy" to prevent rusting as well as liquid damage to electrical parts. A hydrogen tracer-gas mixture is a much safer, dry method for detecting leaks.
Technical Background Information
The INFICION Sensistor Sentrac is a state-of-the-art hydrogen leak detector designed for industrial use in tandem with the company's TGF11 (Tracer Gas Filler). The TGF11 is used to fill test objects with a hydrogen tracer-gas mixture. It then removes the gas after each leak test.
The company's tracer gas filler is a stand-alone unit that also can be used with other INFICON leak detector systems such as the T-Guard Leak Detection Sensor and the Protec P3000 Helium Leak Detector.
An INFICON customer that switched to Sensistor Sentrac and TGF11 to test 15-liter diesel engines reduced the time required to rework faulty components from eight hours to 15 minutes after leaks were identified.
When testing transmissions and engines, INFICON recommends pressurization of a tracer gas (5% hydrogen/95% nitrogen) at 3-5 PSI to prevent damage to seals and other pressure-sensitive items. Hydrogen gas is considerably less expensive to use than helium.
After filling, Sensistor Sentrac's sniffer probe can be used to search for leak locations. In the case of very large leaks, a zero button is available. "Zeroing is only necessary in the case of very large background leaks," Parker explains. "The probe also includes an integrated display for operator convenience and confidence."
After leaks are identified, the TGF11 then vents the gas from the part so that the gas does not build up in the test area which in turn would affect the reliability of subsequent tests.
Available in desktop and battery-operated models, Sensistor Sentrac provides the operator with a moving bar graph on its hand-held probe and an undulating tone to further help in locating leaks. It then can quantify and display the size of the leak in a variety of available standard units such as sccm or atm-cc/sec.
Depending on the component and type of leak involved, operators often are able to perform simple on-the-spot repairs such as tightening a fastener.
Sensistor Sentrac has a dynamic range which enables its use in finding large as well as small "pinpoint" leaks. The sensor also will not "choke" from tracer-gas saturation, permitting near-continuous operation. It calibrates reliably to NIST (National Institute of Standards and Technology) traceable leak standards. Its many features offer higher levels of performance compared to less expensive hand-held devices.
"The commitment INFICON makes to process knowledge, consulting and training for our customers greatly increases the success our equipment has achieved throughout the automotive industry," Parker concludes.
INFICON is one of the world's leading developers, producers and suppliers of instruments and devices for leak detection in air conditioning, refrigeration and automotive manufacturing. The company has manufacturing facilities in Europe, China and the United States, as well as sales and service offices throughout the world.
SourceÂ
INFICON
Contact: U.S. COMPANY CONTACT: Naomi Kissel-Johns, Marketing Communications Manager, Phone +1-315-434-1122, E-mail: Naomi.KisselJohns@inficon.com; EUROPEAN COMPANY CONTACT: Sandra Seitz, Market Manager Automotive, Phone: +49-221-56788-629, E-mail: Sandra.Seitz@inficon.com
Web Site: http://www.inficonautomotive.com
