As we’ve covered in previous blog posts, condensate is an unavoidable by-product of compressing air. It is mostly water with small amounts of oil, so before disposal, it generally needs to be filtered to remove traces of oil to allow safe, cost effective disposal of the water into wastewater systems. This post will focus on the components of the disposal process and best practices for effectively removing condensate from your air system and directing it to the filters.

• Gravity separation: As compressed air cools, water condenses out and, due to its higher density, collects at the bottom of tanks and piping drip-legs to reach installed drains. 
• Centrifugal separation: For aerosols that don’t settle with gravity, centrifugal separators spin the compressed air in a container, forcing water to the outer walls. From there, gravity moves the water to the drain. 
• Mechanical separation: Like centrifugal separation, but instead, air changes direction abruptly, and the water droplets impact the separator walls. Gravity then pulls the water toward the drain. 
• Coalescing filters: These filters capture small water or oil aerosols, allowing them to coalesce and form larger droplets. The heavier droplets then fall to the drain by gravity.

In all these methods, the condensate collects at the bottom of filters, tanks, or pipes. To prevent build-up of water, drains should always be installed at these low points.

• Placement: Install drains at the bottom of filters, aftercoolers, tanks, and heat exchangers (like dryer evaporators). 
• Piping: Ensure piping slopes slightly downward to guide water and oil to a low point where a drain can collect it. We recommend sloping to a corner away from the compressors and away from the end use. 
• Vent lines: When a drain is slightly higher than the lowest point in a tank, add a vent line to displace air and allow the drain to release condensate. 
• Isolation valves: Place a ball valve between the drain and the component to isolate it for maintenance. 
• Y-strainers: Consider using Y strainers in dusty environments to keep drains clear, and check them regularly. Clogged strainers block condensate from reaching the drain. 
• Dedicated drains: Avoid using a single drain for multiple condensate sources, as this can interfere with proper filtration and air flow. Stick to one drain per condensate source. 
• Drip legs: Use drip legs in the piping to catch any condensate that the dryer may miss, especially as an indicator of system issues (e.g., dryer failure, dryer overload, dryer bypass). Drip legs can also be used at points of use along with filter regulators to drain water (if present).
• Cold weather precautions: In freezing environments, use heaters and insulation to prevent condensate from freezing. Frozen condensate can impede air flow, and if enough condensate is present, it can damage equipment. 
• Zero loss drains: Select a drain that doesn’t release compressed air unnecessarily such as electronic demand drains or float drains. Avoid drains with timers as they can waste air.

After the drain, the condensate is typically piped to a condensate filter. Here are some guidelines for setting up the tubing: 

• Pipe length and pressure: Remember that pressurized condensate can only travel so far, depending on pipe size and pressure. Do not exceed manufacturer recommended limits. 
• Avoid back pressure: Long or undersized piping, or pipes that rise too high, can create back pressure, preventing the drain from releasing condensate properly. 
• Separate lines: Avoid combining two drain outlets; pressure from one can interfere with the other’s function. 
• Check valves: Check valves can be used, but note that they can stick and cause condensate back ups.
• Condensate headers: In large systems, condensate headers can collect from multiple sources. Slope the header downward to guide condensate to the filter. 
• Corrosion-resistant materials: Use materials resistant to corrosion, as condensate can be harsh on certain kinds of pipe material. 
• High-pressure systems: In high-pressure systems, consider relief chambers to safely depressurize the condensate and air (if present) before filtering.

For the final discharge of the cleaned condensate into the wastewater system, follow these best practices: 

• Downward slope: Ensure lines slope down to avoid blockages and backflow. 
• Heating in cold climates: Use heating and insulation to prevent lines from freezing and blocking condensate flow. 
• Prevent blockages: prevent foreign matter from blocking the outlet condensate lines.
• Proper pump sizing: If using a pump, make sure it’s sized to avoid backups. 
• Condensate collection: If collecting clean condensate in waste containers, ensure the containers are maintained and emptied regularly to prevent backups.

• Condensate management products by KAESER
• Parts one and two of the condensate management series
• Blog: Don't throw your compressed air down the drain