Air Compressor Drain Valve Open or Closed

Air compressor drain valve open or closed

When it comes to operating an air compressor, there is no one-size-fits-all answer to the question of whether or not to keep the air compressor drain valve open or closed. Some air compressor manuals recommend leaving the drain valve open at all times, while others recommend closing it when the unit is not in use. According to the Central Pneumatic brand manual from Harbor Freight, it is recommended to leave the drain open during prolonged storage in order to prevent corrosion and rust. This article will discuss whether you should keep the drain valve open or close when the compressor is not in use.

What is the solution?

I have looked into this issue for several days and have discovered a sizable debate around that topic. Some people recommend leaving the drain valve open while others advocate closing it. My finding is that you should keep the valve close. One thing you must ensure is that the air tank is dry enough before closing the drain valve.

The best practice is to ensure that when you want to store the compressor for a long time, for example, one month, two months, or longer, keep the drain valve open at least one day for the moisture inside to dry. You can then close the valve to prevent any unwanted objects from entering through the drain valve.

I have gone through many forums regarding this issue. Some people suggest keeping the drain valve open. Let’s be informed on how a metal starts to rust. Rust, or iron oxide, is a common corrosion product that forms when iron or steel is exposed to oxygen. The rusting process occurs when the metal atoms lose electrons to the oxygen atoms, forming an oxide layer on the surface of the metal. The oxygen in the air forms a new compound called iron oxide.

So, there is a high chance for the air compressor tank of rusting from inside if they are left open for a long time. Keeping the drain valve open means, exposing it to air.

The controversy I have collected

Air compressor drain valve open or closed controversy

Importance of water drainage

If you have an air compressor, you know that it’s important to drain the water from the tank on a regular basis. It is one of the important part of air compressor maintenance. Otherwise, the water will rust the tank and cause other problems. However, if you simply close the drain valve after draining the water, you’re not giving the water on the surface of the tank a chance to dry.

As a result, it will eventually build up and start to cause problems. To prevent this, make sure to open the drain valve and let the air circulate for a few minutes before closing it again. This will allow any residual water to evaporate, preventing it from causing damage to your air compressor.

Draining water from an air tank is very easy

If you have an air compressor, it’s important to drain the water from it after each use. Water can build up in the compressor over time and cause rust and other damage. Simply open the valve and let the water run out. In order to open the drain valve, simply turn it counterclockwise until it’s completely open. Once you’re finished using the compressor, remember to close the valve by turning it clockwise.

The best way to drain water is to tilt the compressor (if the compressor is small enough to tilt) so that all the water comes out. This may take a few tilts, but it will ensure that all the water is removed. By following these simple steps, you can help keep your air compressor in good working condition.

For hassle free drainage, you may install an electric automatic drain valve

Installing an automatic drain valve is an easy way to make sure that your tank is kept free of water. These valves open and close at set intervals, allowing the water to drain out while keeping the air in. As a result, you’ll never have to worry about your tank becoming full of water again.

Water drainage frequency

While the frequency with which you need to drain your air compressor will vary depending on factors such as the ambient temperature and humidity levels, as a general rule, it is a good idea to drain the unit after every use.

If you notice that your air compressor is struggling to reach its target pressure, or if the air coming out of the unit seems wet, then it is likely time to drain the unit. Industrial air compressors deposits more water compared to small home use air compressors. To do so, simply turn off the power and release any pressure that has built up inside the unit. Then, open the drain valve and allow all the water to run out. If the compressor is for nail guns, drain it as frequently as possible because water may cause problem to the guns if they are subject to water.

If your air compressor is equipped with an automatic drain valve, then you can simply set it to drain on a regular basis. By following these simple tips, you can help keep your air compressor in good working condition.


My suggestion is to keep the drain valve closed. You may have a different opinion on whether to leave the air compressor drain valve open or closed. Please contact us through our web page if you have any further suggestions to share.

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