AS9120B, ISO 9001:2015, AND FAA AC 0056B ACCREDITED

Understanding Drain Valves Their Working Principles Types and Applications

While not as corrosive as strong acids or as viscous as some crude oils, water can still pose a risk to important machinery when it is left to collect in the wrong areas. Since the air in and around a system can often include some level of moisture, many mechanical systems will employ a drain valve to make sure collected water has a method to escape. Also used to help remove other unwanted fluids, gasses, or contaminants, drain valves are helpful components in industrial machinery which help protect them against blockage or corrosion. In this blog post, we will discuss the benefits of drain valves, exploring their working principles, different types, and their applications to help explain why they are so prevalent in industrial systems.

Working Principles of Drain Valves

Drain valves operate on the principle of controlled fluid flow to remove unwanted substances from a system or chamber. The working mechanism varies depending on the type of valve, but the ultimate goal is always to provide a controlled outlet for draining fluids or gasses. To accomplish this, drain valves will typically consist of a valve body, actuator, and an outlet. Of these parts, the actuator controls the opening and closing of the valve, while the body and outlet provide a route which fluid or gas can exit through to leave a chamber. More specifically, when the valve is open, the fluid or gas is allowed to flow out, and when closed, it prevents any further drainage.

Types of Drain Valves

While all drain valves share the same three parts, their actuator can either be manual, automatic, electric, or motorized to best suit the needs of a variety of applications. As the name suggests, manual drain valves require human intervention to open and close. Often simple in design, they rely on a lever, handle, or knob to control the valve's operation. As a result, manual drain valves are commonly used in small-scale applications or systems where periodic maintenance or inspection is required.

Conversely, automatic drain valves are designed to operate without human intervention. These valves incorporate various mechanisms such as float balls, solenoids, or timers to control the valve's opening and closing based on predetermined conditions or intervals. They are particularly useful in large-scale systems where continuous drainage is necessary, such as air compressors and air dryers.

As a type of automatic drain valve, electric drain valves utilize an electric actuator or solenoid to control the valve's operation. These valves are often used in applications where precise timing or remote operation is required, and they are commonly found in air compressors, refrigeration systems, and industrial equipment.

The other major type of automatic drain valve is the motorized drain valve. Employing a motor-driven actuator, these valves offer precise control and are suitable for applications where high flow rates or large volumes of fluids need to be drained. Consequently, motorized drain valves typically find application in industrial systems, engine oil pans, and large-scale hydraulic systems.

Applications of Drain Valves

Drain valves are versatile components which have found use in a myriad of industries. However, there are some applications which are more common than others. Firstly, drain valves are frequently used for automotive and industrial engines to help drain engine oil. In particular, these valves allow for clean and hassle-free oil changes by providing a controlled outlet for draining old oil. As a result, they eliminate the need for traditional drain plugs and minimize the risk of spills and environmental contamination.

Another common usage for drain valves is in air compressors, which often accumulate moisture, oil, and contaminants during operation. Drain valves in air compressors enable the removal of condensation and other unwanted substances, ensuring the longevity and efficiency of the system. For this purpose, automatic drain valves are particularly beneficial because there is a need for regular removal of such substances. Similar to the way that air brings in moisture and contaminants to air compressors, air dryers also need to be fitted with a drain valve to ensure the delivery of clean, dry air. Automatic drain valves are also frequently used in air dryer systems to provide continuous and efficient drainage.


Drain valves are a core part of many automotive engines, air compressors, air dryers, and other assemblies because of the functions they offer. By using a drain valve, you can protect a system by continuously removing undesired moisture, oil, or contaminants. For access to over 2 billion new, used, obsolete, and hard-to-find industrial and aviation equipment such as drain valves, pipe fittings, and more, you can depend on Integrated NSN. Our widespread network of suppliers guarantees expedited shipping for all our customers, whether they are located domestically or internationally. Start the purchasing process today when you browse our online catalog of components, and experience all that we can do to simplify the procurement process as your strategic sourcing partner.


Semiconductor's Certifications and Memberships
The only independent
distributor with a
  • All Orders are fulfilled in the U.S.A.
  • All shipments must comply with U.S.A export laws.
  • No exceptions.

“We Proudly Support Intrepid Fallen Heroes Fund that serves United States Military Personal experiencing the Invisible Wounds of War : Traumatic Brain Injury (TBI) and Post Traumatic Stress (PTS). Please visit website ( and help in their valiant effort”.

Thank You for Visiting.

We Hope that You Will Visit Us Again the Next Time You Need NSN Parts and Make Us Your Strategic Purchasing Partner.

Request for Quote