The Purpose of Drain Valves

Posted on: June 29, 2023

When you use a rotary screw or reciprocating air compressor, water vapor is released. It then condenses into a liquid, falling to the bottom of the air tank. A drain valve helps to remove the accumulated water before it causes significant damage to the compressor, which would require extensive repairs or replacement.

Learn more about why you should drain water from compressed air tanks, how drain valves help and how to complete an air compressor drain valve replacement.

What Is the Drain Valve?

A condensate drain valve is a small device typically located at the bottom of a compressor’s air receiver. The drain valve opens and closes depending on whether the water flows out of the tank or remains inside.

The drain valve assists with draining the reservoir tank and other compressor components. An air compressor valve extension could help with elements like:

  • Compressor filters
  • Air dryers
  • Drip legs
  • Air or water separators
  • Other areas that accumulate moisture

What Is the Purpose of an Air Compressor Water Drain Valve?

In its natural state, air can hold a substantial amount of water vapor. When you create compressed air, the process significantly reduces the air’s vapor-holding capacity. The compression process forces water molecules to clump together and form condensation, similar to the way a rainstorm forms in the atmosphere.

Drain valves allow excess water vapor to exit the tank and reach the atmosphere. Condensation buildup can result in corrosion that damages the compressor, shortening its life span. By removing the extra moisture, you reduce wear on equipment powered by compressed air systems.

Types of Drain Valves

Drain valves are available in many types, meeting the needs of different system components. Examples include:

  • Float-operated: This valve allows water to flow into a special housing. When the water inside the tank reaches a predetermined level, a float triggers the drain’s opening and lets the excess water drain out.
  • Timer-controlled: A timer-controlled valve opens and closes at pre-set intervals. This type of system is ideal for highly regulated operating environments.
  • Zero-loss: This drain valve type contains a sensor probe that monitors water accumulation inside the tank. When the water reaches a specified level, the probe delivers an electrical signal to a solenoid. The drain then opens, but the water flow stops before the release of compressed air.

How to Use a Drain Valve

Each of the drain valve types listed above operates automatically, meaning little or no manual intervention is necessary. The biggest challenge is finding a model that’s compatible with your equipment and meets your operating requirements.

For example, a float-operated unit would suit a compressor far away from an electrical source. A timer-controlled version is likely the best option if you operate your compressor on a regular schedule. A zero-loss air compressor drain valve works well if you’re concerned about minimizing the loss of compressed air during draining.

How to Replace a Drain Valve on an Air Compressor

Drain valves are essential for proper air compressor function. If they start showing signs of wear, you should replace them as soon as possible. For instance, a compressor drain valve leaking air could cause severe problems in its operation.

Excessive condensation, rust or corrosion can prevent the valve from sealing completely and holding the proper amount of pressure. If the valve cannot open, more moisture and rust can build within the tank. Replacing the valve keeps the component in its best shape and extends its life span.

Tools You Need for a Drain Valve Replacement

Valve replacements don’t require any specialized tools — you can use basic pieces like:

  • A new valve
  • A hand wrench or a socket
  • A brush or cloth to clean the rust or dirt from the threads
  • Safety glasses

New valves come with applied sealant, so you don’t need to purchase additional products.

Drain Valve Replacement Steps

Drain valve replacements begin with tank depressurization. Open the drain valve and wait for all of the air to escape before proceeding with the next steps.

When the air has escaped, you can remove the old drain valve with these instructions:

  1. Unplug the compressor.
  2. Move the compressor on its side to expose the valve.
  3. Turn the wrench counterclockwise to loosen and detach the valve.
  4. Remove any debris from the valve threads.

Once the valve is detached, you can begin installation. Remove the new valve from its packaging and follow these steps:

  1. Turn the new valve counterclockwise to insert it into the tank.
  2. Apply the wrench to tighten and secure the new valve.

Contact Quincy Compressor for All Your Drain Valve Needs

The drain valve plays a crucial role in air compressor performance. Knowing when and how to replace it keeps your air compressor operating at its best. If you need a new drain valve, contact Quincy Compressor today.

We have been a leading compressed air equipment innovator since 1920. Our team of professional and knowledgeable air experts can help with any drain valve questions or replacement projects. Contact us to learn more about our available products and maintenance services.


Last Updated on June 29, 2023 at 8:45 am