Leak Testing Case Studies: Fuel Tank Leak Testing

Client: Tier 1 Multi National Car Manufacturer

Part: Fuel Tanks

Machine supplied: Helium leak test system with functional test and conveyor system

Overview: This system was designed and manufactured in order to give the customer the ability to test fully assembled plastic fuel tanks within their production environment. TQC developed this system alongside the client to allow them to helium leak test and then check the rollover check valves and the float sensor.
Download details of this system as a PDF

Helium leak testing for fuel tanks - mass spectrometer dry test

TQC has specialised in the automatic helium leak testing of components for many years. Fuel tanks have previously been regarded as a leak testing problem - the volume is unstable and too large for air decay testing. Water dunk testing is operator dependent and causes longer term damage to the unpainted tank. Neither method will detect a fine vapour leak.

  • Quantifiable leak testing
  • Calibration to ISO 9000
  • Fast, clean and dry test
  • High sensitivity
  • Automated pass/fail limits
  • No drying costs and no tank water damage

Now proven by several installations, TQC is able to supply Fuel Tank Leak Testing using Helium. The system provides a fast reliable dry test with numerical leak results. The sensitivity is equivalent to a "dunk tank bubble" once in several days. Connections to the tank are made automatically, the system is self-monitoring and the operator may be unskilled. The system is suitable for leak testing metal or plastic tanks.

Typical specification for a 75 litre plastic fuel tank is:

Throughput 48 second cycle (twin station unit)
Test Pressure 200mbar (3psi)
Pass / fail limit 10-4 mbarl/sec (0.1mm3/sec)
Helium usage approx 8000 tanks/standard cylinder

The Pressure Sequence

1. Pump chamber and tank

2. Dose tank when chamber reaches 0.1mbar

3. Enter measure phase

4. Evacuate helium from tank. Vent chamber

5. Vent tank and chamber

6. Test complete

Description

  • The fuel tank is placed in a supporting cradle which slides into a stainless steel chamber.
  • Operator controls close a safety shielded chamber door.
  • The sequence is automatically started by the door closure.
  • The chamber and tank are pumped down together to a pressure of 180mbar, at which point the tank is isolated from the chamber.
  • The chamber pressure is further reduced to less than 0.1 mbar, during which time the tank pressure is monitored to check for a gross leak.
  • A 10% concentration of helium is dosed into the tank, allowed to disperse, and the chamber is sampled for leakage using a mass spectrometer.
  • After the test, the helium is evacuated, the chamber and tank are vented together to atmosphere, and the door is opened automatically. Results are then logged for SPC analysis.

Vehicle Fuel Systems: Legislation

Total vehicle and component assemblies are subject to a variety of fuel loss legislation requirements. Both US and EC evaporative emmissions requirements are the subject of continued revision and it is advised that the current USA Californian certification standard be adopted as the basis for vehicle component and assembly production acceptance.

TQC have also included helium reuse and recovery systems to reduce helium consumption to less than 1% of a total loss system.

To find out more about how we can help you with your leak testing requirements:

We build all machines in-house, applying our 25+ years experience in specialised test and automated handling machines experience to the engineering projects we undertake. We offer customer support, backup and service call-out for all projects, whatever the size.

Get in touch with us to discuss your requirements and we will be happy to offer our professional advice and visit you at your site.

TQC Ltd, Hooton Street, Carlton Road, Nottingham, NG3 2NJ, United Kingdom
Tel: +44 (0)115 9503561   |   Fax: +44 (0)115 9484642   |   E-mail: sales@tqc.co.uk