Drain valves are designed to drain condensate from anywhere it collects. They are often used in compressed air systems to prevent damage caused by liquid and sludge. Typically, drain valves are installed downstream of the air compressor, after-cooler, compressed air filters, compressed air dryer, drip-legs, and separators. There are many different types of products. Examples include pneumatic drain valves, all-electric drain valves, electronic drain valves, and motorized drain valves. Product specifications and features are important to consider. For example, demand-activated drain valves do not need to be set or pre-set. Devices with a sealed actuation mechanism are unaffected by rust and pipe scale. Non-clogging products often use rifle-porting to permit strainer-free draining.
Electronic drain valves consist of a solid-state timer, solenoid valve, and protective housing. They differ in terms of timer specifications, valve specifications, and available features. Timer specifications for electronic drain valves include interval time, discharge time, supply voltage, current consumption, operating temperature, housing material, and connection type. Manual test switching, light-emitting diode (LED) indicators, and IP or NEMA protection are available features. Valve type, working pressure, temperature, and media temperature are common valve specifications. Typically, electronic drain valves have a valve body made of forged brass or stainless steel. The insulation may be Grade F or Grade H. Although Grade F insulation is industry standard, Grade H provides superior temperature-resistance and longer life.
Motorized drain valves consist of a valve that is connected to a gear motor with a coupling. This design reduces the possibility of misalignment and minimizes the chance of premature valve failure. For protection against corrosion, glass-reinforced seals and steel balls and stems are used. Product specifications for motorized drain valves include interval time, discharge time, supply voltage, operating temperature, maximum pressure, and connection type. Materials of construction include nickel-plated brass and stainless steel. In terms of features, motorized drain valves may include a battery-backup and anti-blockage system. Some systems feature solid-state timing controls and a grounded cord with a plug. Valve working pressure and weight are additional considerations.
Drain valves are manufactured and tested in accordance with national, international, and non-governmental standards. Often, products bear designations such as the CE Mark or the UL Mark. The European Union (EU) requires CE marks for electronic drain valves and electric drain valves that will be sold, or put into service for the first time anywhere in the European community. Drain valves with marks from Underwriters Laboratory (UL) are also available.