Tag: drain port

Wet Receivers and Condensate Drains

Published on by johnball2014Leave a comment
Receiver Tank

For properly designed compressed air systems, air compressors will use primary storage tanks, or receivers.  They are necessary to accommodate for fluctuations in airflow demand and to help prevent rapid cycling of the air compressor.  (Reference: Advanced Management of Compressed Air – Storage and Capacitance)  There are two types of primary receivers, a wet receiver tank and a dry receiver tank.  The wet receiver is located between the air compressor and the compressed air dryer where humid air and water will be stored.  The dry receiver is located after the compressed air dryer.  In this blog, I will be reviewing the wet receivers and their requirements as a storage tank.

Air compressors discharge hot humid air created by the internal compression.  A byproduct of this compression is water.  By placing a wet receiver on the discharge side of the air compressor, this will create a low velocity area to allow the excess water to fall out.  It will also give the hot air time to cool, allowing the compressed air dryers to be more effective.  With wet receivers, it will reduce cycle rates of your air compressors for less wear and store compressed air to accommodate for flow fluctuations in your pneumatic system.

But, there are some disadvantages with a wet receiver.  For compressed air dryers, it is possible to exceed the specified flow ratings.   If the demand side draws a large volume of air from the supply side, the efficiency of the compressed air dryers will be sacrificed, allowing moisture to go downstream.  Another issue with the wet receiver is the amount of water that the air compressor is pumping into it. As an example, a 60 HP air compressor can produce as much as 17 gallons of water per day.  As you can see, it would not take long to fill a wet receiver.  So, a condensate drain is required to get rid of the excess water.

Condensate drains come in different types and styles.  They are connected to a port at the bottom of the wet receiver where the water will collect.  I will cover the most common condensate drains and explain the pros and cons of each one.

  • Manual Drain – A ball valve or twist drain are the least efficient and the least expensive of all the condensate drains. The idea of having personnel draining the receiver tanks periodically is not the most reliable.  In some cases, people will “crack” the valve open to continuously drain the tank.  This is very inefficient and costly as compressed air is being wasted.
  • Timer Drain Valves – These valves have an electric timer on a solenoid to open and close a two-way valve or a ball valve. The issue comes in trying to set the correct time for the open and close intervals.  During seasonal changes, the amount of water going into the wet receiver will change.  If the timer is not set frequent enough, water can build up inside the receiver.  If too frequent, then compressed air is wasted.  Compared to the manual valve, they are more reliable and efficient; but there is still potential for compressed air waste.

    Timer Relay
  • No-waste Drains – Just like the name, these drains are the most efficient. They are designed with a float inside to open and close a drain vent.  What is unique about the float mechanism is that the drain vent is always under water.  So, when the no-waste drain is operating, no compressed air is being lost or wasted; only water is being drained.  The most common problem comes with rust, sludge, and debris that can plug the drain vent.

All wet receivers require a condensate drain to remove liquid water.  But, the importance for removing water without wasting compressed air is significant for saving money and compressed air.  EXAIR also has a line of Intelligent Compressed Air® products that can reduce your compressed air waste and save you money.  You can contact an Application Engineer for more details.

John Ball
Application Engineer
Email: johnball@exair.com
Twitter: @EXAIR_jb

 

Photo: Timer Relay by connectors distribution box.  Attribution – CC BY-SA 2.0

Removing Condensation Is Key To Maintaining Performance

Published on by exaircorpLeave a comment

When air is compressed, it is heated to a point that causes the water or moisture  to turn to vapor. As the air begins to cool, the vapors turn to condensation, which can cause performance issues in a compressed air system. Many times this condensation forms in the basic components in the system like a receiver tank, dryer or filter.

Condensation is formed from water vapor in the air

It’s important to remove this condensation from the system before it causes any issues. There are four basic types of condensate drains that can be used to limit or prevent loss of air in the system.

The first method would be to have an operator manually drain the condensation through a drain port or valve. This is the least reliable method though as now it’s the operator’s responsibility to make sure they close the valve so the system doesn’t allow any air to escape which can lead to pressure drops and poor end-use device performance.

Example of a float drain

Secondly, a float or inverted bucket trap system can be used in plants with regular monitoring and maintenance programs in place to ensure proper performance.. These types of drain traps typically require a higher level of maintenance and have the potential to lose air if not operating properly.

An electrically actuated drain valve can be used to automatically drain the condensate at a preset time or interval. Typically these incorporate a solenoid valve  or motorized ball valve with some type of timing control.  These types of systems can be unreliable though as the valve may open without any moisture being present in the line, which can result in air loss or it may not be actuated open long enough for acceptable drain off. With these types of drains, it’s best to use some type of strainer to remove any particulate that could cause adverse performance.

Lastly,  zero air-loss traps utilize a reservoir and a float or level sensor to drain the condensate and maintain a satisfactory level. This type of setup is very reliable but does require the reservoir be drained frequently to keep the system clean and free of debris or contaminants.

If you have any questions or would like to discuss a particular process, contact an application engineer for assistance.

Justin Nicholl
Application Engineer
justinnicholl@exair.com
@EXAIR_JN

 

Condensation image courtesy of Anders Sandberg via creative commons license

Float drain image courtesy of the Compressed Air Challenge