Lower Operating Costs by Minimizing Compressed Air Leaks

Almost every industry uses compressed air in some capacity. It is often referred to as the “fourth utility” In an industrial setting, next to water, gas and electric. and in many cases, is the largest energy user in the plant. With an average cost of $ 0.25 per every 1000 Standard Cubic Feet used, compressed air can be expensive to produce so it is very important to use this utility as efficiently as possible. When evaluating the performance of a compressed air system, it’s important to look at the system as a whole.

When you operate point-of-use devices at a higher pressure than necessary to perform a certain job or function, you are creating “artificial demand”. This results in excess air volume being consumed, increasing the amount of energy being lost to waste. For example, plant personnel or operators increase the supply pressure in an effort to improve the end use devices performance. When there is a leak in the system, the line pressure will actually begin to drop and performance begins to deteriorate in other areas in the plant. This not only puts stress on the existing compressor but it also leads to the false idea that a larger or secondary compressor is needed.

Here’s a quick reference on how operating pressure can directly affect operating cost:


Our Model # 1101 Super Air Nozzle requires 14 SCFM @ 80 PSIG. Based on the average operating cost of $ 0.25 per 1000 SCF used, it would cost $ 0.21 per hour to operate this nozzle. (14 SCFM x $ 0.25 x 60 minutes / 1000 SCF = $ 0.21)

If you were able to use the same Model # 1101 Super Air Nozzle operating at only 40 PSIG, while still achieving the desired end result, the air demand would decrease to only 8.1 SCFM, reducing the hourly cost to $ 0.12.  (8.1 SCFM x $ 0.25 x 60 minute / 1000 SCF = $ 0.12)

Don’t waste your money

Leaks in a compressed air system can account for up to 30% of the total operational cost of the compressor, wasting thousands of dollars of electricity per year. Some of the more common places for a leak to occur would be at connection points such as valves, unions, couplings, fittings, etc.

In this table, you will see that a certain amount of air volume is lost through an orifice or opening. If you have several leaks throughout your facility, it isn’t gong to take long for the waste and high operating costs to quickly add up as well as potential increases in repair or maintenance costs for the existing compressor. The industry average shows that any leakage more than 10%, shows there are areas where operational improvements could be made in a compressed air system.

Stay tuned to our blog over the next few weeks as we will discuss how following a few simple steps can help optimize your current compressed air system, in many cases, reducing energy costs related to compressed air waste, leading to a more economical operation.

In the meantime, if you have any questions or would like to discuss a particular application or EXAIR product, give me a call at 800-903-9247.

Justin Nicholl
Application Engineer
justinnicholl@exair.com
@EXAIR_JN

 

 

 

 

Intelligent Compressed Air: Distribution Piping

air compressor

An important component of your compressed air system is the distribution piping. The piping will be the “veins” that connect your entire facility to the compressor. Before installing pipe, it is important to consider how the compressed air will be consumed at the point of use. Some end use devices must have adequate ventilation. For example, a paint booth will need to be installed near an outside wall to exhaust fumes. Depending on the layout of your facility, this may require long piping runs.  You’ll need to consider the types of fittings you’ll use, the size of the distribution piping, and whether you plan to add additional equipment in the next few years. If so, it is important that the system is designed to accommodate any potential expansion. This also helps to compensate for potential scale build-up (depending on the material of construction) that will restrict airflow through the pipe.

The first thing you’ll need to do is determine your air compressor’s maximum CFM and the necessary operating pressure for your point of use products. Keep in mind, operating at a lower pressure can dramatically reduce overall operating costs. Depending on a variety of factors (elevation, temperature, relative humidity) this can be different than what is listed on directly on the compressor. (For a discussion of how this impacts the capacity of your compressor, check out one of my previous blogs – Intelligent Compressed Air: SCFM, ACFM, ICFM, CFM – What do these terms mean?) Once you’ve determined your compressor’s maximum CFM, draw a schematic of the necessary piping and list out the length of each straight pipe run. Determine the total length of pipe needed for the system. Using a graph or chart, such as this one from Engineering Toolbox. Locate your compressor’s capacity on the y-axis and the required operating pressure along the x-axis. The point at which these values meet will be the recommended MINIMUM pipe size. If you plan on future expansion, now is a good time to move up to the next pipe size to avoid any potential headache.

Once you’ve determined the appropriate pipe size, you’ll need to consider how everything will begin to fit together. According to the “Best Practices for Compressed Air Systems” from the Compressed Air Challenge, the air should enter the compressed air header at a 45° angle, in the direction of flow and always through wide-radius elbows. A sharp angle anywhere in the piping system will result in an unnecessary pressure drop. When the air must make a sharp turn, it is forced to slow down. This causes turbulence within the pipe as the air slams into the insides of the pipe and wastes energy. A 90° bend can cause as much as 3-5 psi of pressure loss. Replacing 90° bends with 45° bends instead eliminates unnecessary pressure loss across the system.

Pressure drop through the pipe is caused by the friction of the air mass making contact with the inside walls of the pipe. This is a function of the volume of flow through the pipe. Larger diameter pipes will result in a lower pressure drop, and vice versa for smaller diameter pipes. The chart below from the “Compressed Air and Gas Institute Handbook” provides the pressure drop that can be expected at varying CFM for 2”, 3”, and 4” ID pipe.

pressure drop in pipe

You’ll then need to consider the different materials that are available. Some different materials that you’ll find are: steel piping (Schedule 40) both with or without galvanizing, stainless steel, copper, aluminum, and even some plastic piping systems are available.

While some companies do make plastic piping systems, plastic piping is not recommended to be used for compressed air. Some lubricants that are present in the air can act as a solvent and degrade the pipe over time. PVC should NEVER be used as a compressed air distribution pipe. While PVC piping is inexpensive and versatile, serious risk can occur when using with compressed air. PVC can become brittle with age and will eventually rupture due to the stress. Take a look at this inspection report –  an automotive supply store received fines totaling $13,200 as a result of an injury caused by shrapnel from a PVC pipe bursting.

Steel pipe is a traditional material used in many compressed air distribution systems.  It has a relatively low price compared to other materials and due to its familiarity is easy to install. It’s strong and durable on the outside. Its strength comes at a price, steel pipe is very heavy and requires anchors to properly suspend it. Steel pipe (not galvanized) is also susceptible to corrosion. This corrosion ends up in your supply air and can wreak havoc on your point-of-use products and can even contaminate your product. While galvanized steel pipe does reduce the potential for corrosion, this galvanizing coating can flake off over time and result in the exact same potential issues. Stainless Steel pipe eliminates the corrosion and rusting concerns while still maintaining the strength and durability of steel pipe. They can be more difficult to install as stainless steel pipe threads can be difficult to work with.

Copper piping is another potential option. Copper pipe is corrosion-free, easy to cut, and lightweight making it easy to suspend. These factors come at a significant increase in costs, however, which can prevent it from being a suitable solution for longer runs or larger ID pipe installations. Soldering of the connecting joints can be time consuming and does require a skilled laborer to do so, making copper piping a mid-level solution for your compressed air system.

Another lightweight material that is becoming increasingly more common in industry is aluminum piping. Like copper, aluminum is lightweight and anti-corrosion. They’re easy to connect with push-to-lock connectors and are ideal for clean air applications. Aluminum pipe remains leak-free over time and can dramatically reduce compressed air costs. While the initial cost can be high, eliminating potential leaks can help to recoup some of the initial investment. Aluminum pipe is also coated on the inside to prevent corrosion. While an aluminum piping system may be the most expensive, its easy installation and adaptability make it an excellent choice.

It can be easy to become overwhelmed with the variety of options at your disposal. Your facility layout, overall budget, and compressed air requirements will allow you to make the best choice. Once you’ve selected and installed your distribution piping, look to the EXAIR website for all of your point-of-use compressed air needs!

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

Intelligent Compressed Air: How to Develop a Pressure Profile

An important part of operating and maintaining a compressed air system is taking accurate pressure measurements at various points in the compressed air distribution system, and establishing a baseline and monitoring with data logging.  A Pressure Profile is a useful tool to understand and analyze the compressed air system and how it is functioning.

Pressure Profile 1
Sample Pressure Profile

The profile is generated by taking pressure measurements at the various key locations in the system.  The graph begins with the compressor and its range of operating pressures, and continues through the system down to the regulated points of use, such as Air Knives or Safety Air Guns.  It is important to take the measurements simultaneously to get the most accurate data, and typically, the most valuable data is collected during peak usage periods.

By reviewing the Pressure Profile, the areas of greatest drop can be determined and the impact on any potential low pressure issues at the point of use.  As the above example shows, to get a reliable 75 PSIG supply pressure for a device or tool, 105-115 PSIG must be generated, (30-40 PSIG above the required point of use pressure.)  As a rule of thumb, for every 10 PSIG of compressed air generation increase the energy costs increase 5-7.5%

By developing a total understanding of the compressed air system, including the use of tools such as the Pressure Profile, steps to best maximize the performance while reducing costs can be performed.

If you have questions about getting the most from your compressed air system, or would like to talk about any EXAIR Intelligent Compressed Air® Product, feel free to contact EXAIR and myself or one of our Application Engineers can help you determine the best solution.

Brian Bergmann
Application Engineer

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Plumbing Kits Simplify Air Knife Installation

Incorrect plumbing is an all too common problem we deal with on a regular basis here at EXAIR. Many times we receive calls from a customer saying that their Air Knife isn’t producing a high velocity or they are seeing an uneven airflow. In fact we have written many blogs touching on this subject, such as the one I posted a few weeks ago titled, Proper Air Supply & Installation Provides Best Performance or the one titled Typical Compressed Air Plumbing Mistakes by our International Application Engineer John Ball.

Using undersized supply lines can cause excessive pressure drops because they aren’t able to carry the volume of air necessary to properly supply the compressed air device. We commonly reference trying to supply water to a fire hose with a garden hose, it is the same principle. Using restrictive fittings, like quick disconnects, will also contribute to this effect as the ID of the fitting is much smaller than the NPT connection size. Example: Say you are seeing 80-100 PSIG upstream of  an air knife at the pressure gauge, by the time the air passes through a quick disconnect or small ID line and fitting, the actual pressure being delivered to the unit will be much less, possibly as low as 20-30 PSIG depending on the installation. One way to measure the actual pressure being delivered to the air knife would be to install a pipe tee with a pressure gauge right at the inlet of the air knife.

All of our products are shipped with an installation guide referencing the proper recommended pipe sizes for various lengths of supply pipe. When dealing with our Air Knives, since we offer lengths up to 108″, you need to plumb air to multiple inlets for knives that are 24″ and larger. To simplify the installation process, we offer our Air Knife Plumbing Kits. The Plumbing Kits include properly sized nitrile/PVC compressed air hose and brass fittings for our aluminum units. In addition, we now offer 316ss pipe and fittings for our stainless steel and PVDF Super Air Knives for applications requiring superior corrosion resistance. Using the plumbing kits eliminates pressure loss and the need for searching for the proper fittings or possibly using incorrect pipe size.

Aluminum Plumbing Kit
Plumbing Kit for aluminum Super Air Knife

 

SS Plumbing Kit
Plumbing Kit for Stainless Steel and PVDF Super Air Knife

 

If you think you are experiencing less than expected performance from one of our products, please give us a call so we can help.

Justin Nicholl
Application Engineer
justinnicholl@exair.com
@EXAIR_JN

 

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Full-Flow Air Knife Dries Copper Strip

Last week I was working with a customer who was using our 36″ Full-Flow Air Knife to dry a flat copper strip as it exited the rinse cycle of their process. The customer chose the Full-Flow design due to it’s small profile, making it easier to fit into the tight space available to mount to their machine. The customer stated that they flow tested the knife before installation and the knife “worked great” but once mounted, the flow was reduced significantly. They were thinking of returning the unit under our Unconditional 30 Day Guarantee but I offered to help troubleshoot the unit to see if we couldn’t relieve their issue(s).

Full-Flow
The Full-Flow Air Knife is available up to 36″ in either aluminum or 303ss construction.

When they tested the unit external to the machine they were using 1″ hose (our recommendation for a 36″ Air Knife) running to a tee, which stepped down to 1/2″ ID hose going to both rear inlets on the back of the knife. But when they installed the knife, due to space limitations, they reduced the main supply to 3/8″ tubing and plumbed only 1 inlet using a quick disconnect. This explained some of the low output flow with the unit. Using undersized supply lines and quick disconnect cause significant pressure drops due to their small inside diameters. When this occurs, you aren’t able to flow enough volume of air (SCFM) to the knife, which results in reduced performance and uneven flow.

The second issue was how they had the unit mounted to the machine. Wanting to keep the air inlets easily accessible, they mounted the face of the knife (the surface the compressed air runs along) right up to the outside wall of the machine, leaving just a small gap for the output flow and built a protective shield around the unit. The Full-Flow Air Knife will entrain 30 parts of surrounding, ambient air for every 1 part (SCFM) of compressed air used. With the unit being unable to entrain any free air, the output flow is further diminished.

How the Standard Air Knife Works
Illustration showing how the Standard and Full-Flow Air Knives operate.

After increasing the supply line to both inlets, removing the quick disconnect and protective shield and moving the knife back to allow for the air entrainment, the customer called back to advise that the strip was now completely dry.

If you are experiencing reduced performance or need help with the installation of your EXAIR product, give us a call at 1-800-903-9247.

Justin Nicholl
Application Engineer
justinnicholl@exair.com
@EXAIR_JN

 

Step 2 of Optimizing Your Compressed Air System, Find & Fix Leaks

Over the past handful of blog posts I have blogged about topics like understanding the demand on your compressor, creating a system pressure profile,  and the effectiveness of filtering your compressed air.  These are all critical steps in ensuring your compressed air system is optimized for maximum efficiency.   These can also all fall into place with our Six Steps To Compressed Air Optimization.

EXAIR Six Steps To Optimizing Your Compressed Air System
EXAIR Six Steps To Optimizing Your Compressed Air System

Another factor in the six steps is identifying and addressing leaks within your system.   Finding leaks in your compressed air system can be done several ways, one of the oldest methods is to use a soap and water mixture to spray on every joint and see if there is a leak that causes bubbles.   The next method would be to use ball valves and pressure gauges to test each run of pipe to ensure they are holding their pressure over a period of time, similar to a leak down test.  The final method, and by far the easiest, would be to utilize our Ultrasonic Leak Detector.

This can be used to sense leaks in compressed air systems up to 20′ away and can also pin point a leak by closely monitoring each joint.  Neal Raker made a great video on how to use the Ultrasonic Leak Detector a while back and it is shown below.

If you have any questions on how to find leaks or how to optimize your compressed air system, give us a call.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF

3 Common Mistakes in Your Compressed Air System

Every day I speak with engineers who are having trouble using compressed air products. A common problem they have is not providing an adequate air supply to their unit. I go through a basic troubleshooting technique to ensure that their pressure and flow rate is adequate. I ask them to install tee on the inlet to the compressed air product in order to install a pressure gauge right at the inlet to the pipe. This allows us to know exactly what pressure we are supplying to the product. Customers are always surprised how the gauge on the compressor or the regulator may read 120 PSIG, but the gage on the inlet to the compressed air product is significantly less.

Last year, my colleague, Russell Bowman, made an excellent video showing how the inlet pressure at the knife will have a significant impact on the performance of the Super Air Knife.  In the video, he changes the length and ID of the compressed air supply to illustrate the difference a proper supply line will have on the performance of a compressed air products.

Not providing adequate air supply is commonly caused by these three mistakes, when plumbing compressed air systems.

1. Incorrectly Sized Piping – This can be the single biggest problem. A lack of planning before installing a compressed air product. Not all compressed air systems are created equal. Though a 1/4″ shop air hose may work for a number our products, some of our products require a larger air line because they require more volume of air to be effective. We often speak with customers an illustrate this problem by stating small air lines are like trying to feed a fire hose with a garden hose – there simply is not enough volume to create the pressure necessary to reach the fire, or solve the application in our scenarios. We publish the flow rates for all of our products and make inlet pipe size recommendation in the installation and maintenance guide furnish with the products so you may avoid this common problem. We also have air data tables in our Knowledge Base or  you may consult an application engineer who will be happy to make the proper recommendation.

2. Quick Disconnects – These handy connectors are great when operating a brad nailer, or a small blow gun, but the small through diameter can severely limit the flow rate into a long air knife, large diameter air operated conveyor, or big vortex tubes.  Due to this fact it is strongly advised to use threaded fittings or over-sized quick disconnects.

3. Adding extra hose or pipe – Extra hose is never a bad thing, right? No, an extra 30 feet of air hose can significantly drop the pressure of a compressed air system. 20 feet of ½ Pipe can flow 70 CFM with a 5 PSI pressure drop.  50 feet of ½” pipe will only flow 42 SCFM with the same 5 PSIG pressure drop. Keep your hose or pipe lengths to a minimum to improve the volume of air you can deliver to a compressed air product.

Dave Woerner
Application Engineer
DaveWoerner@EXAIR.com
@EXAIR_DW