How to Drain Your Compressed Air System

Draining excess water from your compressed air system is very important to maintain the longevity of your system and keep moisture out of your compressed air supply. Fortunately, draining condensate from your compressed air system is easy with either manual or automatic drain valves. Learn why draining your air compressor, air dryers, air tanks and other components of your compressed air system is important, what kind of drains you need, and how often to drain your air system components.

Ensure your compressed air system remains dry, efficient, and reliable — contact Fluid-Aire Dynamics for professional maintenance today.

Why Is Draining Your Compressed Air System Important?

Draining moisture from your compressed air system is crucial for maintaining efficient, safe, and reliable operations. Moisture naturally enters the system as humidity in the intake air. When air is compressed, the existing moisture is squeezed into a much smaller volume, significantly increasing its concentration. As the compressed air cools after compression, this concentrated water vapor condenses into liquid water.

This condensate accumulates at various points — including compressors, dryers, receiver tanks, and piping — where it can lead to corrosion, weakening critical system components over time. Corrosion not only shortens equipment lifespan but also produces contaminants that degrade air quality and may clog your air distribution system. Additionally, excess moisture in the compressed air supply can damage air-powered tools and machinery, leading to rust, malfunctions, spoilage, and poor-quality finishes for products such as paints and coatings.

Components of a Compressed Air System

Understanding the main components of a compressed air system helps you pinpoint exactly where moisture collects and how to manage it effectively. Key components like the air compressor, aftercooler, receiver tank, air dryers, and piping all play specific roles — and each can become a primary location for water collection, making regular draining essential for maintaining performance and reliability.

• Air compressor: Generates pressurized air for system use.
• Aftercooler: Lowers the temperature of air after compression.
• Air dryer: Removes excess moisture to provide clean, dry air.
• Air receiver tank: Stores compressed air, balancing supply and demand.
• Distribution piping: Carries compressed air throughout the facility.
• Condensate drain: Removes liquid buildup from system components.

Step-by-Step-Guide to Draining Your Air Compressor and System Components

Regularly performing moisture removal by draining your air compressor is essential for protecting your compressed air system from corrosion and maintaining optimal performance. Follow our clear step-by-step guide, and always observe proper safety precautions and follow all manufacturer instructions to ensure safe and efficient operation of your equipment.

Draining Piston Compressors with Integrated Air Tanks

Small reciprocating (piston) compressors typically have integrated air tanks with manual valves.

Instructions:

1. Turn off and unplug the compressor, and fully depressurize the air tank.
2. Place a container under the tank’s drain valve.
3. Open the drain valve slowly, allowing water to drain fully.
4. Close the valve securely once all condensate has been drained.
5. Restart and repressurize your compressor.

Draining Industrial Rotary Screw Compressors

Larger rotary screw compressors usually have automated or zero-loss drains, eliminating the need for frequent depressurization.

Instructions:

1. Check automatic drain valves regularly, confirming proper operation. (These valves operate without system depressurization.)
2. Verify condensate discharge from receiver tanks, aftercoolers, and dryers.
3. If using manual drain valves (uncommon on large rotary screw compressors):
   • Partially depressurize the component if recommended by the manufacturer.
   • Open valves slowly, allowing condensate to drain completely.
   • Close valves tightly after draining.
4. Inspect drain lines for leaks or blockages regularly.
5. Ensure condensate flows properly into collection systems or separators.

Important note: Automated or zero-loss drain valves provide continuous, efficient drainage without interrupting system operation or requiring depressurization.

Draining Compressed Air System Components (Tanks, Dryers, and Filters)

Receiver tanks, air dryers, and distribution piping also accumulate moisture and require periodic draining.

Instructions:

1. Receiver tanks: Manually drain weekly (or daily in high-humidity conditions), or verify automatic drains weekly.
2. Air dryers: Refrigerated or desiccant dryers typically have automatic drains. Confirm proper operation regularly.
3. Inline filters and aftercoolers: Regularly inspect and manually drain or confirm automated drain functionality according to manufacturer guidelines.
4. Distribution piping: Install and regularly maintain drains at strategic low points to avoid moisture accumulation.

Types of Drain Valves and Draining Frequency

Selecting the right drain valves and determining the ideal draining frequency is key for efficient compressed air system maintenance. Here's a quick overview of the main types and their applications:

Manual Drain Valves

Manual drain valves are simple and economical, typically operated by hand. They’re best suited for smaller air compressors or low-volume condensate situations. Because they must be opened manually, regular attention is essential — usually daily or each shift — to avoid moisture buildup and equipment damage.

Timer-Operated Automatic Drain Valves

Timer-operated drains offer automated convenience by releasing condensate at predetermined intervals. They’re commonly used in mid-sized industrial setups, balancing reliability with simplicity. However, these valves can occasionally release small amounts of air along with the condensate, requiring careful timer adjustments to minimize air loss.

Zero-Loss Automatic Drain Valves

Zero-loss drains provide the most energy-efficient solution, automatically discharging condensate without losing compressed air. While their initial cost is higher, they quickly pay for themselves by eliminating air waste. These valves are ideal for large industrial systems or critical applications where efficiency and performance are top priorities. Even more good news: your power company may have energy incentives available to help cover the cost of upgrading to a zero-loss drain.

Because unresolved moisture can lead to costly equipment damage and downtime, regular professional maintenance is critical. Fluid-Aire Dynamics specializes in diagnosing and resolving complex moisture and system-performance issues. Our team provides comprehensive inspections, preventive maintenance, and efficient moisture management solutions.

For detailed guidance, read our blog: Prevent and Remove Moisture in Air Compressors.

Maintaining Your Compressed Air System: Beyond Draining

Regular draining is just one essential part of compressed air system maintenance. Keeping your system free of moisture not only improves system efficiency but also delivers significant energy savings and enhances air compressor longevity. However, effective maintenance goes beyond routine draining. It includes regular professional inspections, preventive maintenance, and proactive air compressor repair to address issues before they impact your operations.

Fluid-Aire Dynamics specializes in comprehensive professional service for compressed air systems. Our experienced technicians provide the expertise you need to keep your equipment running smoothly, efficiently, and reliably.

Schedule your professional inspection and maintenance service today with Fluid-Aire Dynamics to protect your investment and keep your compressed air system performing at its best.

If you’re seeing excess moisture in your compressed air system, or have questions about drain valves, contact us for help.