Condensate drain (drain trap)

The US Department of Energy compressed air sourcebook (third edition) describes four methods: manual valves, which are too often left open; level-operated mechanical traps, such as float traps; timed solenoid valves, which may not stay open long enough and open even when little or no condensate is present, losing compressed air; and zero air-loss traps with reservoirs, of various types, one of which uses a float or level sensor to operate a valve that keeps the condensate below the high-level point.

HTM 02-01 (2026) asks for receivers to be fitted with electrically operated automatic drains, which it says have been found more reliable, plus a manual drain as a bypass in the event of power loss, and says any discharge from the drainage traps must be piped to a suitable oil separator. For hospital technical air, the Portuguese ACSS ET 08/2010 (V.2025) asks for a reliable automatic drain on each dryer and recommends zero-loss or intelligent drains that open only when condensate is present.

The ULTRAOX oxygen plant includes a water separator with electronic drain in its air treatment, and the customer provides the conditions for collecting or draining the condensate. ULTRATECH has filters fitted with zero-loss drains, and automatic drains with test buttons, and the ACIH system has a condensate treatment unit that removes the oil so the condensate can go to the sanitary network.