Dielectric isolators

摘要

The invention comprises dielectric isolators for use in aircraft fuel systems to control lightning induced current and allow dissipation of electrostatic charge. The dielectric isolators are configured to have a high enough impedance to limit lightning currents to low levels, but low enough impedance to allow electrostatic charge to dissipate without allowing buildup. Although the dielectric isolators may develop a potential difference across the dielectric length due to the effects of lightning currents and its inherent impedance, they are configured to withstand these induced voltages without dielectric breakdown or performance degradation. In one embodiment, the dielectric isolator includes a tube constructed of a composition including a thermoplastic organic polymer (e.g., PEEK) and carbon nanotubes, and a pair of fittings attached to opposing ends of the tube. In another embodiment, the dielectric isolator includes a tube, an outer annular portion, and an interconnecting web, each constructed from the composition including a thermoplastic organic polymer (e.g., PEEK) and carbon nanotubes. This later embodiment is an integrally formed one-piece structure. The dielectric isolator is capable of exhibiting an electrical resistance from about 105Ω to 108Ω at an applied potential of greater than 500 volts DC when measured from one fitting to the other fitting.

主权项

1. A fluid carrying element for use in a fuel system of an aircraft as a dielectric isolator and especially adapted for interconnecting facing ends of a fluid carrying member disposed concentrically within an outer shroud, comprising:
a fluid carrying element within the fuel system of the aircraft including: (i) an inner tubular element interconnecting the facing ends of the fluid carrying member and arranged in an inline configuration with said facing ends; (ii) an outer annular portion interconnecting facing ends of the outer shroud; (iii) a circumferential web interconnecting the inner tubular element to the outer annular portion, said circumferential web including a plurality of openings; (iv) a pair of couplings for securing opposing ends of the outer annular portion to the facing ends of the outer shroud; and wherein the inner tubular element is constructed of a composition including about 50 wt % to 98 wt % of PEEK, about 0.05 wt % to 2.0 wt % of carbon nanotubes; and wherein the inner tubular element composition exhibits a bulk volume resistivity from about 103 Ω-cm to 1010 Ω-cm at an applied potential of 5,000 volts DC.