Ultraform houses fuel filter

German chemical giant BASF recently launched a plastic containing carbon nanotubes (CNT), which has found its first application at Bosch for a fuel filter housing for the Audi A4 and A5.

This material itself is called Ultraform N2320 C, a polyoxymethylene (POM) that, due to the novel additives, acquires a high level of electric conductivity without much of a decrease in toughness.

For some time, the pump and supply units of fuel housings have been made of POM such as unreinforced Ultraform S2320 003 or glass fibre-reinforced Ultraform N2200 G43.

For its filter unit, however, Bosch demanded compliance with SAE standard J1645, which can only be met by a conductive material.

This standard of the Society of Automotive Engineers (SAE) recommends a maximum specific volume resistance of 106ohm/cm for materials that will be used in components through which fuel flows.

Under measuring conditions according to ISO 3915 (four-point method), the conductive Ultraform attains a value of a mere 30ohm/cm, making it 30,000 times more conductive than necessary, so that it meets the requirements of SAE J1645 with ease. This eliminates the risk of electrostatic charging and sparking as fuel flows through the filter.

Thanks to the type of additives and the way they have been incorporated, the new Ultraform has retained its POM-typical properties such as toughness, dimensional stability and elastic resilience.

Moreover, when the material comes into contact with fuels, BASF claims that it is stronger and more creep-resistant than conventional POM, in addition to which it is less costly than other conductive plastics.

It is also easily processed by laser welding and injection moulding. The carbon nanotubes are firmly fixed in the plastic matrix and the material can be handled safely throughout its lifetime. BASF developed Ultraform N2320 C and optimised it for the application in a collaborative effort with Bosch.