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
Email: johnball@exair.com
Twitter: @EXAIR_jb

Photo:  Lightbulb by qimonoPixabay Licence

Pressure Drop Chart by Compressed Air Challenge Organization.

Critical Factors to Consider When Designing Your Compressor Room

One common thing that can be easily overlooked is the importance of designing an efficient compressor room. After you’ve determined your overall requirements and selected the appropriate compressor, you can begin designing the layout of your compressor room. For starters, the compressor room should be located in a central location when possible, close to the point of use. This will help to minimize pressure drop as well as reduce installation costs as less piping will be required. If this isn’t possible, try to keep the compressor room close to the larger volume applications in your facility. Otherwise you will have to use larger diameter piping in order to ensure an adequate volume of air is available.

The diameter of the distribution piping should NOT be based on the connection size of the compressors, aftercoolers, or filters. According to the Compressed Air Challenge Best Practices for Compressed Air Systems handbook, piping should be sized so that the maximum velocity in the pipe is 30 ft/sec. When the distance between the compressor room and the point of use is lengthy, consider increasing the pipe diameter to minimize the pressure drop across the system.

Inside of your compressor room you’ll have a variety of different equipment, all dependent on the demand, quality, supply, storage, and distribution of your compressed air. Keeping all of the equipment in its own room will also provide some insulation from the noise associated with compressed air generation. It is crucial that the space selected as your compressor room is sufficiently large enough to accommodate everything without becoming cramped. As a general rule of thumb, keep about 3′ of space between equipment such as the compressor, receiver tanks, aftercooler, and dryer. This helps to prevent equipment from overheating as well as offers maintenance personnel adequate space with which to perform any regularly scheduled maintenance or repairs.

Once you’ve selected your equipment, piping, and determined the location, another thing to consider is ventilation. As compressed air is generated, the compressor gives off a good amount of heat. It is important that the exhaust air is not permitted to re-circulate throughout the compressor room. The exhaust needs to be ducted so that it the warm air is not drawn in at the air intake on the compressor. Some equipment, such as refrigerated dryers, require a substantial amount of cooling air. In these situations, an exhaust fan can be used to provide that additional airflow.

To further enhance the efficiency of your facility, the heat generated from compression can be re-purposed instead of simply exhausting into the ambient environment. This process is commonly referred to as compressed air energy recovery. Some industries require a source of heat for many of their manufacturing processes. In these scenarios, the heat energy that is produced during compression can be reused rather than having to generate another source of heated air. If the heated air can’t be used for any of your manufacturing processes, the heat can be used as a means to heat your water supply or even to heat the facility itself. This can drastically reduce your electricity or gas requirements during cooler periods.

To reduce the amount of required maintenance and ensure that your compressor is operating as efficiently as possible, the compressed air intake must also be free from particulate and harmful gases. When dust and dirt is drawn into the compressor, it can cause wear on the internal components. If the ambient environment contains a lot of dust and particulate, a pre-filter can be used to prevent any future problems. In these instances, it is important to consider the pressure drop that will be caused when designing the system.

Keeping these tips in mind will serve to make your life much easier in the long run. Once you have everything installed and set up, visit the EXAIR website or give us a call to speak with an Application Engineer. EXAIR’s Intelligent Compressed Air Products  can help you reduce compressed air consumption and increase worker safety by adhering to both OSHA 1910.242(b) and 1910.95.

Tyler Daniel
Application Engineer
E-mail: TylerDaniel@exair.com
Twitter: @EXAIR_TD

Image Courtesy of  thomasjackson1345 Creative Commons Attribution-NoDerivs 2.0 Generic (CC BY-ND 2.0)

Six Sigma and The Compressor Room

Throughout my undergrad courses as well as during my professional career I have encountered Six Sigma or Lean Manufacturing in many facilities.  There is at least one component to the theory that can be implemented into any facility with a compressor room. That component is the practice of the 5 S’s.

The 5 S’s of Lean Manufacturing come from the Japanese terms  listed below with their English translations:

Seiri – Sort (Organize)
Seiton – Set in Order (Orderliness)
Seiso – Shine (Cleanliness)
Seiketsu – 
Standardize
Shitsuke –  Sustain (Discipline)

These 5 points can aid in keeping any air compressor room in a facility efficient, safe, and effectively supplying the company with compressed air. How you may ask.

Sort – Keeping a compressor room as originally laid out and preventing it from being a catch-all for items that have nothing to do with the compressed air system. This can easily happen when it is actually a room that has unused floor space in a small facility. By keeping the area clean and free of unrelated materials, maintenance and troubleshooting can be done quickly. Clear labeling of anything kept in the room is also ideal to make items easily identified.

Set in Order – To deliver the air in a single path/direction as well as keeping equipment in locations where they can be easy to maintain and clearly labeled eases the troubleshooting and understanding of how the system is laid out. Rather than having a spaghetti bowl of piping running all around the room to different components it is wiser to keep a flow that matches the process. From the compressor(s) to the receivers, dryers, filter, and regulators, out to the point of use. This shouldn’t be a tangled web of piping that introduces air to a process which bypasses key components such as the dryer or receivers.

Block diagram of a compressor room layout.

Shine – The compressor room shouldn’t be a dirty grungy area. The compressor pulls the air in from this environment. Any exposed components easily collect airborne debris. By keeping the equipment clean again makes labels easy to read and a clean machine is always easier to perform maintenance and sometimes even troubleshoot. If there are puddles of oil or other liquids on the floor and no surfaces are clean then any leak may not be easily spotted.

Standardize – The layout and processes used within the room should be repeatable. Maintenance tasks should be performed on a schedule, per a process that doesn’t allow for much differentiation on methods and end results. This mitigates errors and is always the desired result when focusing on lean manufacturing. LOWER THAT DELTA!

Sustain – This is sometimes the hardest part of any process. Getting the program up and running, starting with a fresh build is always the easiest.  Everything is fresh, new and you want to keep it shiny. Years later the desire to dust and maintain piping as well as keep receiver tanks and floors clean isn’t always at the top of the desired list.  It should always be a priority because cleanliness also promotes safety and reduces overhead by lowering downturns due to housekeeping related failures.

If you want to discuss how we can help lean out your compressed air usage, maintenance costs, and help to standardize the use of compressed air in your facility, contact an Application Engineer today.

Brian Farno
Application Engineer – Green Belt Certified
BrianFarno@EXAIR.com
@EXAIR_BF

Compressor Room Updates Improve Performance

I’d like to start out by saying a common theme I have observed over the past six months is a huge spike in DIY projects around the home. While everyone has been sent home to work and kids have been sent home to learn remotely, the home has become more than just a resting place. It is an office, school, recreation center, even movie theater. This led to an amazing year for home improvement big box stores and lots of people are tackling projects that they may have thought were beyond their level. At this point in the year we are also seeing a lot of manufacturing that either hasn’t stopped or is starting back up safely, there are lots of projects around an industrial facility that can be tackled during downturns as well.

Compressor Room – 1

The main focus today will be on a critical room that generally gets shoved back into a deep dark corner, the compressor room. The air compressor is a piece of capital equipment that generates a companies 4th utility, compressed air. This is then sent throughout most of the facility and utilized at critical points within production. Air compressors have changed their look over the years and are still often crammed into a small dimly lit room that no one wants to venture into. Having an outdated compressor room can also be causing undesirable performance and lack luster performance as well. Here’s a few items that can more often than not be addressed pretty simply to improve the overall appearance and most importantly the performance of the compressors.

Clean air intake on a screw compressor – 2

First, clean air intake. Rather than letting the compressor suck air in from the room that may be stagnant or even worse, just sucking in the hot air coming off the heat exchangers on the compressor and causing elevated compressed air temps. This fix can include ducting clean air from outside of the facility to ensure micro-debris from within the facility isn’t being pulled in. While pulling in ambient air from outside the facility will still require a filter that will need to be maintained. If a large single source is used, that is perfectly acceptable. To step this project up multiple smaller inlets that are each controlled by a damper would permit variability to match ambient conditions on temperature.

Industrial exhaust fan – 3

Second, install an exhaust fan that feeds the air not just out of the room, yet out of the facility if at all possible. This helps to promote a through-flow of air with the clean air intake and keep from recirculating dirty already cycled air. This will also help any form of system based air treatment that relies on an exchange of heat, such as a refrigerant dryer. Again, a fan that stays on constantly would be the base level fix, step this up by adding a thermostatically controlled system so the fan doesn’t run continuously.

Third, if you heat your facility throughout the winter, use that hot exhaust air from the compressors to reclaim the heat of the compression cycle and optimize your return on using electricity. This can be done by strategic routing of the exhaust ductwork mentioned above, and can be stepped up to have thermostatically controlled dampers on the ducts to open and flow the air through an adjacent room for cooler months rather than exhaust straight out during the warm Summer months.

If you would like to discuss any of these topics or any of your compressed air point of use applications, feel free to contact us.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF

 

 1 – Air Compressor in Engine Room – retrieved from, Work With Sounds / CC BY-SA (https://creativecommons.org/licenses/by-sa/4.0) – https://commons.wikimedia.org/wiki/File:Air_compressor_in_engine_room.JPG

2 – Screw Compressor 1 – retrieved from, Endora6398 / CC BY-SA (https://creativecommons.org/licenses/by-sa/4.0) – https://commons.wikimedia.org/wiki/File:Screw_compressor_1.jpg

3 – Industrial Exhaust Fan – retrieved from , Saud / CC BY-SA (https://creativecommons.org/licenses/by-sa/4.0) – https://commons.wikimedia.org/wiki/File:Industrial_Exhaust_Fan.jpg