The Purpose of Drain Valves

The Purpose of Drain Valves

Posted by AVP on Feb 1st 2021

    The Purpose of Drain Valves

    One byproduct of using a rotary screw air compressor is water vapor. Having a drain valve is necessary as water vapor condenses into liquid and drops to the bottom of the air tank. The drain valve then helps to remove the water that has been accumulated at the bottom of the tank before it causes significant damage to the compressor.

    What Is the Drain Valve?

    A drain valve is a smaller device that is generally located at the air receiver. When the drain valve is open the remains will flow out of the compressor tank and if it is closed the liquid will remain. While many times the reserve tank is the installation location for the drain valve, it can also help remove moisture from other compressor components and products.

    What’s the Purpose of a Drain Valve?

    Basically all air withholds a substantial amount of water vapor. Creating compressed air will significantly reduce the ability to hold as much vapor which can cause condensation build up and ultimately moisture to collect.

    The drain valve allows excess water vapor to escape into the environment which helps prevent corrosion that will possibly reduce the life expectancy of the compressor because of corrosion. The drain valve will also help reduce wear on other parts of the compressor unit as well.

    Types of Drain Valves

    Examples of the many types of air compressor drain valves include:

    Solenoid Electric Drain EDV-115: 

    The inexpensive and reliable Terminator electric automatic drain valve automatically removes condensate from your air system. It has an integral strainer to prevent clogging and saves time and money by eliminating the need for manual draining. The Terminator automatic drain valve also eliminates the need for the wasteful practice of bleeding, or leaving cracked open manual drain valves. Click here to calculate the cost of bleeding a compressed air drain.

    Check out a few of our favorites:

    Motorized Drain Valves: 

    Whether you need the simplicity of a basic valve or the flexibility of added features, the Sentinel Series is your solution. Choose from two models, plus different options and accessories to fit the level of adjustment and controls you need. For the most dependable draining, install the Van Air Sentinel Series motorized ball valve. The Sentinel’s heavy-duty ball valve can manage virtually any fluid in a wide variety of applications. Depend on it for nearly any fluid service.

    ROBO-Drain Pneumatic Zero-Loss Drain Valves: 

    The Robo Drain RD Series Drain Valve is a versatile draining system ideal for receivers, dryers, tanks, drop legs, pipes, and any equipment requiring regular condensate removal. With no electricity required for operation, the pneumatically operated RD Series automatic drain valve is well suited for remote or portable applications and is safe to operate in any hazardous area. 

    As a demand-operated drain, the RD Series Drain Valve automatically does the work of draining for you, eliminating the guesswork of setting the cycle time of the timed drain valve. As condensate levels change, the RD Series automatic drain valve automatically adjusts to drain as needed, without permitting valuable compressed air to escape.

    Designed with a full flow ball valve and proprietary pilot valve using a magnet and proximity switch, the RD Series Drain Valve will not clog. This unique pilot valve design allows the control air to be totally separated from the condensate, preventing any attraction of pipe scale. The ball valve eliminates the need to install a strainer. This means better dependability than competitive units.

    The see-through vessel allows visual inspection of the condensate. The test button, which is included on both the brass and stainless steel units, make it easy to check valve operation or manually drain the system. There are many versions available in our online store, vertical & horizontal units, extra sump capacity, all stainless steel, high-pressure design and valves for vacuum service.

    Zero-Loss Drain Valve: 

    Aircel Ultramat UFM-T zero air-loss condensate drain valve has a compact design allowing for installation in restricted space applications. The UFM-T is designed to open only when necessary and close before any loss of compressed air can occur. The unique internal reservoir and flow channels reduce the possibility of blockage and minimize fouling of the drain valve seat allowing more thorough processing at a downstream oil/water separator.

    Optimization of compressed air systems can provide energy efficiency improvements of 20 to 50 percent. One contributor to the inefficient use of compressed air, which can increase cost, is the condensate drain. Liquid condensate, which naturally accumulates in various spots within a compressed air system, must be drained frequently or serious consequences can adversely impact downstream hardware, finished products and the compressed air system itself.

    Typical drains that operate on a timer allow compressed air to vent from the systems with every cycle. Timer operated drains will open regardless of how much, or how little, condensate has collected between cycles. In addition, float drains are subject to fouling and allow compressed air to bleed out of the system even when the float is resting in its seat.

    Check out some of our favorites:

    How to Use a Drain Valve

    For each of the drain valves listed above there is little or no manual intervention necessary. One of the bigger challenges can be in choosing a model that’s compatible with your equipment and meets your operating requirements.

    Trust the Experts

    We know the list provided is not extensive but that was intentional. Taking just these few basic steps can be a great start in cutting costs and saving money in the short run and increase the longevity of your compressor and saving more money in the long term.

    At AVP, we know a thing or two about air compressors. Call us for an expert recommendation at (281) 866-9700 or check out our store at