Nylon Fittings Made from engineering grade 6/6 virgin resin. Nylon fittings are generally acceptable for use at working pressures up to 150 psi at ambient temperature. At very low pressures, temperatures may approach 175 F with no degradation in the performance of the nylon fitting. Nylon has good resistance to a fairly broad range of chemicals including most agricultural chemicals, ammonium compounds, detergents, diesel fuel, ethanol, gasoline, hexane, magnesium sulfate, most sodium compounds, trichlorethylene and zinc sulfate. Nylon fittings should not be used with acid-based fertilizers, bromine, chlorine, flourine, hydrochloric acid, iodine, nitric acid, phosphoric acid, sulphuric acid and xylene.