scope:

This part of ISO 4639 specifies requirements for vulcanized compounds and rubber tubing and hoses for use in fuel circuits where the fuel can become oxidized or 'sour'. These fuels may or may not contain compounds such as alcohols. This part of ISO 4639 does not cover any equipment used for the distribution of liquid fuels, nor tubing totally immersed in fuel tanks. The hoses and tubing are used in recirculating fuel injection systems and in other systems which, having been charged with fuel, may be subject to exceptional storage conditions at high ambient temperatures. Such hoses and tubing are typically provided with an inner veneer of a speciality elastomeric compound.