Test Application from TQC
Leak Testing of Automotive Fuel Pipes
TQC designed and manufactured 2 helium leak test systems
for the automatic testing of plastic fuel pipes. The systems included
bespoke tooling to accommodate 2 variants of fuel pipe.
The helium leak test machine is split into three modules:
- A Centre Module containing the primary controls (Touch
screen HMI), vacuum pumps, mass-spectrometer, electrical cabinet,
bar code printer and scanner.
- Two Test Modules, each containing pneumatically sealing
test chamber and localised control and monitoring equipment.
The components are loaded independently into each
test chamber, attaching onto the pneumatically expanding seal connector.
As each component has three entry points, all of these must all
be sealed prior to commencing testing using:
- A threaded sealing plug. This is screwed into the threaded
insert within the fuel pipe assembly prior to loading the component
into the test chamber.
- A mechanically operated expanding seal. This is fitted
into the breather pipe within the fuel pipe assembly prior to
loading the component into the test chamber. Ensure orientation
does not restrict the location of the test component.
- A pneumatically operated expanding seal. This forms the
primary insertion point/datum with the rubber hose on the fuel
pipe assembly fitting over it. The seal is expanded automatically
using an integrated pneumatic piston as part of the test cycle.
Leak Test Equipment
CAD Layout of the System
Once the part is sealed correctly, it is placed into the test chamber
and over the pneumatically operated expanding seal. The lid is then
pulled down over the test chamber to the closed position and the
cycle start button operated for that chamber on the centre module
The part is sealed from the chamber and the chamber is sealed from
atmosphere. The component is then evacuated to a pre-set level and
held there for a time interval to monitor for any large leak created
by the pressure differential (termed 'Gross Leak'). A fail
at this point will reset the cycle.
If the test is passed then both the component and the chamber are
evacuated to a lower pre-set level. A fixed volume of Helium is
then injected into the component producing a 140mBar pressure differential
between the component and chamber. The chamber vacuum line is switched
to the mass-spectrometer which monitors for helium leakage from
the component into the chamber (termed 'Fine Leak').
A label printer will dispense the appropriate label based upon
the data entered by the operator if the test was successful. This
is scanned using a hand-held barcode reader for verification.
Any components that fail due to gross or fine leaks are held for
The leak location test requires the component to be evacuated,
then filled with Helium at 1140mBar Absolute (to produce the 140mBAR
pressure differential above atmospheric) A hand-held probe connected
to the mass-spectrometer is then used to manually locate helium
concentrations indicating leaks in the test component
Pipe loaded into Test Chamber
If you have a current project that you are
already looking at, or you are considering improvements to your
production in the near future, call us and we will be happy to offer
our professional advice & visit you at your site.