Air compressors are the great facilitators of our modern world, making so many different tasks not only more comfortable but possible. The speed and amount of compressed air vary with the size and type of air compressor but, on average, can range between 100 to 175 pounds per square inch (PSI). This pressure represents a tremendous amount of stored energy, powerful enough to run pneumatic tools and shop equipment.
With so much air under so much pressure, can you leave an air compressor full?
The short answer is yes, it is perfectly safe to leave an air compressor full. However, this assumes that it has been properly maintained, with regular draining to remove accumulated moisture from inside the tank. So while under regular duty cycles, a full air compressor is standard, but during extended non-use, an air compressor should be drained and deactivated.
In this article, I will explain why it is vital to drain the system of compressed regularly. You will see that it is the nature of compressed air itself that makes regular draining necessary.
Why is it Necessary to Drain Your Air Compressor?
Ambient air, which is the air that is all around us, naturally contains water vapor. The amount of this moisture varies with weather conditions; for instance, it increases with warmer temperatures and decreases when it gets colder. Air compressors take in ambient air and pressurize it to create compressed air.
Air compressors do precisely what their name suggests; they compress or squeeze air into a pressurized state. As the ambient air is compressed, the water vapor is pressed or condensed out of the air. Much like rainwater in a cloud, the moisture forms more extensive and larger droplets until it drops to the lowest spots to which it is confined; ultimately, water will collect at the bottom of the compressor’s tank.
There are three primary reasons to drain compressed air systems regularly:
- To protect the air compressor tank from corrosion – Even though most companies treat the interior lining resist rust, water is still highly corrosive to metal. Over time, prolonged contact will eventually prevail. Since air compressor tanks are designed to store highly pressurized air, you need to do everything you can to preserve their integrity, which means removing moisture as frequently as possible. Other air compressor components need to be protected from moisture as well, including pressure switches, safety release valves, and parts on the outlet side.
- To protect devices and equipment – Draining the tank not only protects the compressor from moisture but also any pneumatic tools and machinery downstream that use the compressed air because tiny water droplets in the pressurized air will travel in the supply line on the outlet side. Particularly sensitive to moisture are equipment components such as air cylinders and valves.
- To improve the Quality of the job – example: woodworking applications can result in warping of wood exposed to unwanted moisture, spray painting, and airbrushing can have visual defects; and rust can form on metal surfaces.
How Often Should You Drain Your Air Compressor?
The frequency of the draining system is ultimately determined by usage and humidity. What is important to remember is that The more often that your compressor processes air, the more by-product water that will be created.
Many manufacturers will include a recommended maintenance routine in their owner’s manuals, and most advise that draining the air compressor should be a daily activity. Even if your air compressor’s pump cycles only a handful of times per day, you should drain your compressor tank every other day or several times per week to prolong its operating life and to protect your pneumatic devices and equipment.
How to Drain Your Air Compressor – A Step-by-Step Guide
The following steps can be used for virtually any size or type of compressor that utilizes a storage tank where moisture can accumulate. (It should be noted that each new compressor will include an operating manual that contains the manufacturer’s specific guidelines relating to the recommended frequency and procedures for draining its air compressors.)
Step One:
The first step is to power down the air compressor. This is a critical safety step as you do not want the compressor to engage while relieving tank pressure. If the compressor has a power switch with an “OFF” position, then power down this way; otherwise, unplug the unit or shut off its power source.
Also, it is advisable to wear protective eyewear (e.g., goggles or safety glasses) to shield your eyes from possible spraying debris, as well as earplugs due to the noise associated with relieving tank pressure.
Step Two:
Next, turn the regulator setting down to zero. Some air compressor manufacturers also recommend disconnecting the outlet air supply line (the one feeding your devices and machinery) at this time as well.
Step Three: Locate your safety release valve. It should be identifiable by a metal ring at the end of it that is used to pull it open. Safety release valves are spring-loaded, meaning that when they are pulled, they will release compressed air, but when they are released, they automatically pull themselves shut and re-seal.
Remember that you will be releasing highly pressurized air. Once the safety release valve ring is pulled, compressed air will shoot out of the opening at a high velocity, and it will be loud. Continue to pull on the ring until all the
compressed air has been released, and the tank pressure gauge reads below 10 PSI.
Step Four:
Once the compressor tank has been entirely de-pressurized, it is safe to drain accumulated moisture from the tank. At or near the bottom of the tank, there should be a drain fitting or valve that will allow accumulated moisture to exit the tank.
On most air compressor tanks, the drain valve will have a lever or handle that, when turned 90 degrees, will open and release water from inside the tank. On rare occasions, there will be a hex fitting or nut that must be removed using a wrench, but newer compressors are fitted with devices that make draining tanks much more accessible than in years past.
Step Five:
Once all moisture has been drained from the tank, the drain valve must be closed completely. Failure to completely close the drain valve will allow compressed air to escape, forcing the motor and pump to work that much harder to maintain adequate air pressure.
Once the drain valve has been properly closed, re-set the pressure regulator back to its original setting and re-attach the outlet supply line. You are now ready to power your air compressor back on and resume normal operations.
Electronic Drain Valves and Other Compressor Accessories
When things are busy, it is easy to overlook or forget to drain an air compressor on any day. Many newer air compressors, particularly larger ones, have automatic drain valves installed that can self-drain when a certain amount of moisture is detected, or according to a built-in programmable timer. Manufacturers also offer this feature as an additional option that can be ordered at the time of purchase.
In addition to automatic drain kits, there are also after-market accessories such as drain extension kits that make the job of draining compressors easier and more convenient to perform.
In Conclusion
Owning an air compressor is like having your own compressed air production plant that is always ready to supply as much of this valuable resource as you need. Many of today’s air compressors even take care of themselves by draining their tanks automatically. With a little care and mindfulness, an air compressor can continue to provide pressurized air to fill all your pneumatic needs for many years.