The 686 Series Self-Actuating Drain Valve, commonly known as the Drain-matic, is designed to exhaust liquid contaminants from the locomotive air reservoir without any pneumatic or electrical signals. The valve works on the Bernoulli principle whereby a steel disc moves and seats upon a steel valve body. Like other GW drain valves, an integral drain/shut-off feature to manually exhaust contaminants, or disarm the valve as desired, is available. Each 686 Series Self-Actuating Drain Valve is supplied with a flange-type mounting bracket for ease of installation on AAR type reservoirs. A heater thermostat assembly is available in several voltages for severe weather applications to prevent freezing.