Typically, the leak test of fuel rails is performed with the use of a Tracer Leak detector in the 500 -03 sensitivity range. However, there are some applications that are less or more sensitive. Most Tier Suppliers will require a production rate of110 parts per hour and are typically tested in a Small Hard Vac or Small Hard Vac customized system.
Key Considerations for the accurate and repeatable test of fuel rails are:
Vacuum Instruments Corporation has been designing and manufacturing customized systems to test these parts as well as other Power Delivery Applications for decades. During this time, we have developed and innovated several System, Test and or Fixturing differentiators, to include:
Careful attention to the test-part pressure is critical. Damage to the parts’ integrity and part distortion can easily occur without precise pressure monitoring. At VIC we specialize in proven techniques to ensure proper part evacuation and charging during the entire leak test process.
Our well established hard-vac leak testing capabilities provide reliable and repeatable leak test results on critical fuel tank applications. Our live helium part percentage correction techniques allow for accurate leak rate readings, even with the challenge of low pressure charging as found in fuel tank applications. Part support and fixturing are also critical items that VIC has demonstrated experience in for accurate leak testing of fuel tanks.
High-pressure, direct-injection fuel rails have a maximum allowable leak rate spec of 10-4 atmospheric cubic centimeters per second (atm-cc/sec). Leak testing fuel rails with helium, often with the fuel injectors installed, in a vacuum chamber is a common process.
A fuel rail is essentially a tube that delivers gasoline to individual fuel injectors in an internal combustion engine. Formerly, vehicle manufacturers designed fuel rails to withstand pressures of only 30 to 60 psig, a minimum requirement for port injection. Nowadays, to meet more stringent standards for fuel economy, emissions, and efficiency, fuel rails have been redesigned to withstand much higher pressures—up to 5,000 psig and beyond.
Greater test pressures mean greater helium usage, warranting the need for a helium recovery system. In order to avert additional helium costs associated with the higher test pressures, many companies have installed a VIC helium recovery system that would reclaim up to 98% of the helium used. Even with the cost of the recovery system and the installation to retrofit a customer’s machines, the cost of the new system can be recouped in a little over a six-month period.