What Makes A Compressed Air System “Complete”?

It’s a good question.  When do you know that your compressed air system is complete?  And, really, when do you know, with confidence, that it is ready for use?

A typical compressed air system. Image courtesy of Compressed Air Challenge.

Any compressed air system has the basic components shown above.  A compressed air source, a receiver, dryer, filter, and end points of use.   But, what do all these terms mean?

A compressor or compressed air source, is just as it sounds.  It is the device which supplies air (or another gas) at an increased pressure.  This increase in pressure is accomplished through a reduction in volume, and this conversion is achieved through compressing the air.  So, the compressor, well, compresses (the air).

A control receiver (wet receiver) is the storage vessel or tank placed immediately after the compressor.  This tank is referred to as a “wet” receiver because the air has not yet been dried, thus it is “wet”.  This tank helps to cool the compressed air by having a large surface area, and reduces pulsations in the compressed air flow which occur naturally.

The dryer, like the compressor, is just as the name implies.  This device dries the compressed air, removing liquid from the compressed air system.  Prior to this device the air is full of moisture which can damage downstream components and devices.  After drying, the air is almost ready for use.

To be truly ready for use, the compressed air must also be clean.  Dirt and particulates must be removed from the compressed air so that they do not cause damage to the system and the devices which connect to the system.  This task is accomplished through the filter, after which the system is almost ready for use.

To really be ready for use, the system must have a continuous system pressure and flow.  End-use devices are specified to perform with a required compressed air supply, and when this supply is compromised, performance is as well.  This is where the dry receiver comes into play.  The dry receiver is provides pneumatic capacitance for the system, alleviating pressure changes with varying demand loads.  The dry receiver helps to maintain constant pressure and flow.

In addition to this, the diagram above shows an optional device – a pressure/flow control valve.  A flow control valve will regulate the volume (flow) of compressed air in a system in response to changes in flow (or pressure).  These devices further stabilize the compressed air system, providing increased reliability in the supply of compressed air for end user devices.

Now, at long last, the system is ready for use.  But, what will it do?  What are the points of use?

Points of use in a compressed air system are referred to by their end use.  These are the components around which the entire system is built.  This can be a pneumatic drill, an impact wrench, a blow off nozzle, a pneumatic pump, or any other device which requires compressed air to operate.

If your end use devices are for coating, cleaning, cooling, conveying or static elimination, EXAIR Application Engineers can help with engineered solutions to maximize the efficiency and use of your compressed air.  After placing so much effort into creating a proper system, having engineered solutions is a must.

Lee Evans
Application Engineer
LeeEvans@EXAIR.com
@EXAIR_LE

Types Of Compressed Air System Dryers

Many times, when discussing product selection with a customer, we commonly reference supplying as clean and dry air as possible to promote peak performance. In iron piping systems for example, when moisture is present, rust can develop which can reduce the performance of end use compressed air operated devices like air tools or cause issues on the exhaust side as you could exhaust unwanted mist onto a surface, like in a painting operation.

Example of a desiccant dryer

Typically, an efficient and properly installed industrial compressed air system will include some type of dryer to remove any moisture that may be present in the supply.

Let’s take a look at the various types of dryers available.

Refrigerant and desiccant dryers are two of the more commonly used types of dryers.

Refrigerant based systems have several stages. The compressed air first passes through an air to air heat exchanger  which initially cools the air. The air is then delivered to an air to refrigerant exchanger where an external source of liquid refrigerant further cools the air and sends it to a separator, where the water vapors condensate and are removed through a drain trap. Now that the air is dry, it is then cycled back to the air to air exchanger where it is heated back to ambient temperature and exits the system.

Desiccant dryers typically incorporate 2 tanks containing a porous desiccant which causes the moisture to sort of “cling” to the surface. In these systems, compressed air flows through one tank, while, using it’s own regeneration cycle, heated or unheated air is blown through the desiccant in the other tank to remove the moisture and dry the air.

Membrane Dryers are typically used at the end use product. These types of systems utilize membranes to dissipate water vapor as it passes through the material, while allowing a small amount of the dry air to travel the length of the membrane to sort of “wipe” the condensate and remove it from the system.

Deliquescent Dryers use a drying agent which absorbs any moisture in the air. As the vapors react with the desiccant, like salt, the desiccant liquefies and is able to be drained at the bottom of a tank. These are the least expensive dryers to purchase and maintain because they have no moving parts and require no power to run.

When a dryer is being considered for a particular setup, there are 3 common reference points used when determining the dryers rating – an inlet air temperature of 100°F, supply pressure of 100 PSIG and an ambient air temperature of 100°F. Changes in supply pressure or temperature could change the performance of a particular dryer. You want to follow the manufacturer’s recommendations when dealing with variances as they will typically provide some type of conversion.

For help with this or any other topics relating to the efficient use of compressed air, please give us a call, we’d be happy to help.

Justin Nicholl
Application Engineer
justinnicholl@exair.com
@EXAIR_JN

 

Heated Desiccant Dryers image courtesy of Compressor1 via creative commons license

Video Blog: Effectiveness of Filtering Your Compressed Air

The video below will give a brief demonstration on the importance of point of use filtration in order to remove unwanted material such as water, scale, particulate and oil from your compressed air stream. Point of use or end-use filtration will keep your air clean and your compressed air products running smooth.  If you have any comments or questions, please feel free to contact us.

 

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF