When compressed air is cooled, it produces condensate, a combination of water vapor and aerosol in liquid form. Condensate is a normal byproduct of cooling, but it can be dangerous for the compressed air system if not removed properly.
Condensate forms in various parts of the compressed air system including pipes, dryers and filters. When condensate is not correctly removed, it can cause components in the compressed air network to work at a reduced capacity, eventually impacting compressed air quality at the end use. Condensate that sits in piping can also corrode the material, introducing small particulates into the air stream or leading to leaks. To prevent this, condensate is usually collected from the air stream by coalescing filters or removed mechanically by cyclonic or impingement separators. Once collected, the condensate needs somewhere to go. There are three ways to remove condensate: manual valves, level-operated mechanical traps and electrically operated solenoid valves.
Manual valves are opened by operators to removed condensate. Because they are not automatic, they must be checked regularly. If left open, they can allow compressed air to continually escape. This can make the compressed air work harder, using more energy and driving up operating costs.
Level-operated mechanical traps open once a specific level of condensate is reached within the trap. There are two types: float-type traps and inverted bucket traps. While float-type traps don’t waste compressed air like manual valves, they can require lots of maintenance and are easily blocked. Inverted bucket traps are another type of level-operated mechanical trap. They require less maintenance than float-type traps, but can waste significant amounts of compressed air.
Electrically operated solenoid valves use electromagnetic impulses to time valve openings at predetermined intervals. However, this can cause problems. Depending on the timing and condensate rate, these valves may not be open long enough to fully drain the condensate. Conversely, they can be left open too long, wasting compressed air.
Zero-air loss traps do not waste air when removing condensate and are highly reliable. Some use a float or level capacitance sensor to operate an electric solenoid, while others use a float to mechanically drain the condensate. (Note: Zero air-loss drains are a type of level operated mechanical or electrical drain, not a class of drain.)
It’s important to know what type of condensate drain your compressed air uses. Without proper selection, attention or maintenance, drains can waste compressed air or incompletely remove condensate. Regular inspections and audits of this and all system components can help prevent system inefficiencies.
