This standard covers reinforced and flexible hoses intended for use in water and ethylene glycol based engine coolant system application. Compounds based on different synthetic rubber grades are specified and designated Class A, high temperature resistant; Class B, high oil swell resistant; Class C, medium oil swell resistant; Class D-1, low oil resistant, improved service; Class D-2 low oil resistant, standard service; Class D-3, low oil resistant, high temperature resistant, premium service; Class E, low oil resistant, fiber elastomer composite. Typical physical characteristics for each type hose are shown in Table 1.