Which of the following is a common application for AN fittings?

AN fittings, or Army-Navy fittings, are primarily designed for use in applications that require pressure and strength, making them particularly suitable for hydraulic systems. The correct answer highlights the importance of these fittings in systems that transport fluids under pressure, where the integrity and reliability of the connections are crucial.

These fittings are characterized by their accurate thread dimensions and the use of a flared end that provides a tight seal when connected with a matching flared fitting. This design minimizes the risk of leaks and allows for the efficient transfer of hydraulic fluids, which often operate under high pressures in various machinery and equipment.

While AN fittings could technically be used in other systems, such as fuel lines or coolant lines (related to systems), they are specially engineered for the demanding conditions typically encountered in hydraulic systems. The other options, such as electrical connections and water systems, do not usually require the specific characteristics of AN fittings, such as their robustness and ability to withstand high pressures. This distinction makes their application more aligned with hydraulic systems than with the other alternatives listed.