Compressed Air Distribution System, Keeping Pressure Drop to a Minimum

Compressed air is used to operate pneumatic systems within a facility, and it can be separated into three categories; the supply side, the demand side, and the distribution system.  The supply side is the air compressor, after-cooler, dryer, and receiver tank that produce and treat the compressed air.  They are generally located in a compressor room somewhere in the corner of the plant.  The demand side is the collection of devices that will use that compressed air to do “work”.  These pneumatic components are generally scattered throughout the facility.  To connect the supply side to the demand side, a compressed air distribution system is required.  Distribution systems are pipes which carry the compressed air from the compressor to the pneumatic devices.  For a sound compressed air system, the three sections have to work together to make an effective and efficient system.

An analogy that I like to use is to compare the compressed air system to an electrical system.  The air compressor would be considered the voltage source, and the pneumatic devices would be marked as light bulbs.  To connect the light bulbs to the voltage source, electrical wires are needed which will represent the distribution system.  If the gauge of the wire is too small to supply the light bulbs, the wire will heat up and a voltage drop will occur.  This heat is given off as wasted energy, and the light bulbs will be dim.  The same thing happens within a compressed air system.  If the piping size is too small, a pressure drop will occur.  This is also wasted energy.  In both types of systems, wasted energy is wasted money.  One of the largest systematic problems with compressed air systems is pressure drop.  If too large of a pressure loss occurs, the pneumatic equipment will not have enough power to operate effectively and efficiently.  As shown in the illustration below, you can see how the pressure decreases from the supply side to the demand side.  With a properly designed distribution system, energy can be saved; and, in referencing my analogy above, it will keep the lights on.

Pressure Drop Chart

To optimize the compressed air system, we need to reduce the amount of wasted energy.  This can be caused from leaks or pressure drop.   Leaks can be hidden and are typically located at connections within the distribution system.  In a poorly maintained system, a study found that 30% of the compressor capacity is lost through air leaks on average.  Even though leaks are the “silent killer” to a compressed air system, they can be found with the Ultrasonic Leak Detector

Pressure drop is more of a wide range issue.  It is based on restrictions, obstructions, and piping surface.  Out of these, restrictions are the most common types of pressure drops. The air flow is forced into small areas, causing high velocities.  The high velocity creates turbulent flow which increases the losses in air pressure.  Flow within the pipe is directly related to the velocity times the square of the diameter.  So, if you cut the I.D. of the pipe by one-half, the flow rating will be reduced by 25% of the original rating.  Restriction type of pressure drop can be found in different forms like small diameter pipes or tubing; restrictive fittings like quick disconnects and needle valves, and undersized filters, regulators and valves.

As a rule, air velocities will determine the correct pipe size for the distribution system.  It is beneficial to oversize the pipe to accommodate for any expansions in the future.  For header pipes, the velocities should not be more than 20 feet/sec (6 meter/sec).  For the distribution lines, the velocities should not exceed 30 feet/sec (9 meter/sec).  In following these simple rules, the distribution system can effectively supply the necessary compressed air from the supply side to the demand side.

To have a properly designed distribution system, the pressure drop should be less than 10% from the reservoir tank to the point-of-use.  By following the tips above, you can have the supply side, demand side, and distribution system working at peak efficiency.  If you would like to reduce waste even more, EXAIR offers a variety of efficient, safe, and effective compressed air products to fit within the demand side.  This will include the EXAIR Super Air Knives, Super Air Nozzles, and Safety Air Guns.  This would be the pneumatic equivalent of changing those incandescent light bulbs into LED light bulbs.  If you wish to go further in optimizing your system, an Application Engineer at EXAIR will be happy to help you. 

John Ball
Application Engineer
Twitter: @EXAIR_jb

Photo:  Lightbulb by qimonoPixabay Licence

Pressure Drop Chart by Compressed Air Challenge Organization.

Intelligent Compressed Air: Compressed Air System Components

In any manufacturing environment, compressed air is critical to the operation of many processes. You will often hear compressed air referred to as a “4th utility” in a manufacturing environment. The makeup of a compressed air system is usually divided into two primary parts: the supply side and the demand side. The supply side consists of components before and including the pressure/flow controller. The demand side then consists of all the components after the pressure/flow controller.

The first primary component in the system is the air compressor itself. There are two main categories of air compressors: positive-displacement and dynamic. In a positive-displacement type, a given quantity of air is trapped in a compression chamber. The volume of which it occupies is mechanically reduced (squished), causing a corresponding rise in pressure. In a dynamic compressor, velocity energy is imparted to continuously flowing air by a means of impellers rotating at a very high speed. The velocity energy is then converted into pressure energy.

Still on the supply side, but installed after the compressor, are aftercoolers, and compressed air dryers. An aftercooler is designed to cool the air down upon exiting from the compressor. During the compression, heat is generated that carries into the air supply. An aftercooler uses a fan to blow ambient air across coils to lower the compressed air temperature.

When air leaves the aftercooler, it is typically saturated since atmospheric air contains moisture. In higher temperatures, the air is capable of holding even more moisture. When this air is then cooled, it can no longer contain all of that moisture and is lost as condensation. The temperature at which the moisture can no longer be held is referred to as the dewpoint. Dryers are installed in the system to remove unwanted moisture from the air supply. Types of dryers available include: refrigerant dryers, desiccant dryers, and membrane dryers.

Also downstream of the compressor are filters used to remove particulate, condensate, and lubricant. Desiccant and deliquescent-type dryers require a pre-filter to protect the drying media from contamination that can quickly render it useless. A refrigerant-type dryer may not require a filter before/after, but any processes or components downstream can be impacted by contaminants in the compressed air system.

Moving on to the demand side, we have the distribution system made up of a network of compressed air piping, receiver tanks when necessary, and point of use filters/regulators. Compressed air piping is commonly available as schedule 40 steel pipe, copper pipe, and aluminum pipe. Some composite plastics are available as well, however PVC should NEVER be used for compressed air as some lubricants present in the air can act as a solvent and degrade the pipe over time.

Receiver tanks are installed in the distribution system to provide a source of compressed air close to the point of use, rather than relying on the output of the compressor. The receiver tank acts as a “battery” for the system, storing compressed air energy to be used in periods of peak demand. This helps to maintain a stable compressed air pressure. It improves the overall performance of the system and helps to prevent pressure drop.

Finally, we move on to the point-of-use. While particulate and oil removal filters may be installed at the compressor output, it is still often required to install secondary filtration immediately at the point-of-use to remove any residual debris, particulate, and oil. Receiver tanks and old piping are both notorious for delivering contaminants downstream, after the initial filters.

Regulator and filter

In any application necessitating the use of compressed air, pressure should be controlled to minimize the air consumption at the point of use. Pressure regulators are available to control the air pressure within the system and throttle the appropriate supply of air to any pneumatic device. While one advantage of a pressure regulator is certainly maintaining consistent pressure to your compressed air devices, using them to minimize your pressure can result in dramatic savings to your costs of compressed air. As pressure and flow are directly related, lowering the pressure supplied results in less compressed air usage.

EXAIR manufactures a wide variety of products utilizing this compressed air to help you with your process problems. If you’d like to discuss your compressed air system, or have an application that necessitates an Intelligent Compressed Air Product, give us a call.

Tyler Daniel
Application Engineer
Twitter: @EXAIR_TD

Compressor Image courtesy of Compressor1 via Creative Commons License

Piping and Instrumentation diagrams (P&ID)

When it comes to drawings and diagrams to map out a process system, the piping and instrumentation diagrams (P&ID) are a great way to situate and find components.  They use different symbols to represent the type of products, the layout in the system, installation, and process flow.  These standard symbols are created by ANSI or ISO.  They are used in electrical, hydraulic, and pneumatic processes.  Since EXAIR has been manufacturing Intelligent Compressed Air Products since 1983, I will cover some pneumatic symbols and the process flow in this blog.

A colleague, Russ Bowman, wrote an article about “Knowing Your Symbols Is Key To Understanding Your Drawings”.  As a reference, air compressors are the start of your pneumatic system, and there are different types as represented by the symbols below.

The one on the left can be used for any air compressor. The others denote specific types of air compressor (from left:) Centrifugal, Diaphragm, Piston, Rotary, and Screw.

Air compressors are considered the fourth utility in industries because they use so much electricity; and they are inefficient.  So, you need to use the compressed air as efficiently as possible.  As a typical pneumatic system, the air compressors, receiver tanks and compressed air dryers would be on the supply side.  The distribution system, or piping, connects the supply side to the demand side.  This symbol is represented by a simple line.  The demand side will have many different types of pneumatic devices.  Since there are so many, ANSI or ISO has created some common types of equipment.  But if there isn’t a symbol created to represent that part, the idea is to draw a basic shape and mark it.

From top left, and then down: Automatic Drain Filter Separator, Pressure Regulator, and Super Air Knife

As an example, if I were to do a P&ID diagram of the EXAIR Super Air Knife Kit; it would look like the above diagram.  The kit will include the Super Air Knife with an Automatic Drain Filter Separator and a Pressure Regulator.  The Filter Separator is a diamond shape and since it has an Automatic Drain, a triangle is placed at the bottom.  Filter Separators are used to clean the compressed air and keep the Super Air Knife clean.  The Automatic Drain will discard water and oil from the filter bowl when it accumulates over a float.  The next item is the pressure regulator which is represented by a rectangle with an adjustment knob to “dial in” the desired blowing force.  And at the end, we drew a rectangle, which does represent a Super Air Knife, as marked.

Using the P&ID diagram for the process flow is also important.  You noticed that the Filter Separator will come before the Pressure Regulator.  This is significant when installing this system.  Remember the statement above about “using your compressed air as efficiently as possible”?  Inefficiencies come from two basic areas; pressure drop and overusing your compressed air.  Pressure drop is based on velocity.  The lower the velocity, the lower the pressure drop.  If the Filter Separator is placed after the Pressure Regulator, the lower pressure will increase the velocity.  Since air expands at lower pressure, the volume of air will increase.  And since the area of the compressed air pipe is the same, the velocity will have to increase.   For the second part with overusing compressed air, the Pressure Regulator will help.  You want to use the lowest amount of air pressure as possible for the Super Air Knife to “do the job”.  The lower air pressure will use less compressed air in your operation.

EXAIR products are engineered to be safe, efficient, and effective in your compressed air system.  If you need help to place them in your P&ID diagrams, an Application Engineer can help you.  It is important to have the pneumatic devices in the proper place, and if you want to efficiently use your compressed air, you can use EXAIR products for your blow-off devices.

John Ball
Application Engineer

Twitter: @EXAIR_jb

You Don’t Need to Spend Thousands to Optimize Your Compressed Air System

There is no denying it, saving compressed air is a process.  This process often involves some type of energy audit or at the very least an evaluation of something going wrong with production and a way to improve it.  Many programs, consultants, and sales reps will devise a solution for the problem.

Often times the solution is to create a more efficient supply side of the compressed air system. The supply side is essentially everything within the compressor room or located in close proximity to the actual air compressor. While optimizing the supply side can amount to savings, many of these solutions and services can involve great expense, or capital expenditure processes.  These processes can often lead to delays and continued waste until the solution is in place.  What if there was a way to lower compressed air usage, save energy, solve some demand issues on the compressed air system and save some money while the capital expenditure process goes through for the larger scale project.

These solutions are a simple call, chat, email or even fax away. Our Application Engineers are fully equipped to help determine what points of your compressed air demand side can be optimized. The process generally starts with our Six Steps To Compressed Air Optimization.

6 Steps from Catalog

Once the points of use are evaluated the Application Engineer can give an engineered solution to provide some relief to the strain on your compressed air supply side.  For instance, an open copper pipe blow off that is commonly seen within production environments can easily be replaced with a Super Air Nozzle on the end of a Stay Set Hose that will still bend and hold position like the copper pipe does while also saving compressed air, reducing noise level, and putting some capacity back into the supply side of the compressed air system.

engineered nozzle blow offs
Engineered solutions (like EXAIR Intelligent Compressed Air Products) are the efficient, quiet, and safe choice.

One of the key parts to the solutions that we offer here at EXAIR is they all ship same day on orders received by 3 PM ET that are shipping within the USA. To top that off the cost is generally hundreds, rather than thousands (or tens of thousands) of dollars. Well under any level of a capital expenditure and can generally come in as a maintenance purchase or purchased quickly through the supply cribs.  Then, to take this one step further, when the EXAIR solution shows up within days and gets installed EXAIR offers for you to send in the blow off that was replaced and receive a free report on what level of compressed air savings and performance increases you will be seeing and provide a simple ROI for that blow off (though we would also encourage a comparison before a purchase just so you have additional peace of mind).

This amounts to saving compressed air and understanding how much air is being saved, adding capacity back into your supply side which will reduce strain on the air compressor, give the ability to increase production while the capital expenditure for the end solution of controls and higher efficiency on the supply side is approved to then save even more compressed air and energy.

The point is this, savings and efficiency doesn’t have to involve a capital expenditure, if that is the end game for your project that is great! Let EXAIR provide you a solution that you can have in house by the next business day to save money NOW and then put that savings towards another project. No matter the method, it all starts with a call, chat, email or fax.

Brian Farno
Application Engineer