A valve that operates without manual interaction to open an orifice to remove accumulated condensate water separated from compressed air – through intercoolers, aftercoolers, separators, filters, dryers, receiver tanks, drip legs, or at point of use.
A timer-based valve also bleeds compressed air while draining the condensate at set time intervals. Whereas the condensate liquid level sensing valves drain only the condensate water.
Various technologies of level sensing or draining can fail due to contaminants in the condensate liquid. Corrosion from various internal surfaces of pipes, tanks, coolers as well as lubricant carry over from Compressors cause sticky brown or white liquid which forms coating over the electronic level sensors, clogging the orifices of solenoid valves, strainers that stops the functioning of the condensate draining devices. Hence, they need regular service / maintenance to keep them operating well. When such failure of condensate drains occur, the pipes, receiver tanks accumulate condensate water causing compressed air pressure drop and carry over of liquid particles in the system.
(See also Drains, solenoid valve drains, float drains, sensor drains, timed drains, no-loss drains, zero loss drains)