Tag: cagi

How To Prevent Pressure Drops

Published on by jasonkirbyLeave a comment
Issue 1

Compressed air serves as the essential utility for operation, and its performance limitations are determined by the supply available. To effectively utilize EXAIR products and pneumatic equipment, it is crucial to establish a method for transferring compressed air from the source to the point of use. This can be accomplished through three primary means: pipes, hoses, and tubes.

As compressed air travels through the distribution system, it experiences friction against the inner surfaces of pipes, tubes, and hoses. Factors such as the diameter of the pipe, its length, the number of bends, and the smoothness of the inner wall contribute to this friction. Consequently, a reduction in air pressure occurs due to this resistance. Additionally, pressure drops can also happen at the point of use, particularly if the line is inadequately sized, which can significantly affect the performance of the equipment being powered.

When designing and maintaining a compressed air system, it is essential to take pressure measurements at various locations to detect and resolve potential issues before they escalate. The Compressed Air Challenge recommends specific points for regular pressure assessments to accurately gauge the operating pressure of your system.

  • Inlet to compressor (to monitor inlet air filter) vs. atmospheric pressure
  • Differential across air/lubricant separator
  • Inter-stage on multistage compressors
  • After-cooler
  • At treatment equipment (dryers, filters, etc.)
  • Various points across the distribution system
  • Check pressure differentials against manufacturers’ specifications. If high pressure drops are noticed, this indicates a need for service.

After taking the necessary measurements, you should sum the recorded pressure drops and subtract this total from your compressor’s operating range. The resulting value represents the actual operating pressure at the point of use.

If your distribution system is correctly sized and the pressure drops across your equipment are within acceptable limits, any pressure drop observed at the point of use suggests a lack of sufficient air volume. This issue may stem from restrictive fittings or inadequately sized air lines, hoses, or tubes. It is essential to ensure that the point of use product is installed in accordance with the manufacturer’s specifications for compressed air.

If you have questions about pressure drops, or anything regarding EXAIR and our products, please do not hesitate to reach out.

Jason Kirby
Application Engineer
Email: jasonkirby@exair.com
Twitter: @EXAIR_jk

A Journey of Learning: Passing the CCASS Certification Test

Published on by Jordan T ShouseLeave a comment

Hey everyone! I’m beyond excited to share some big news with you—I recently passed the Certified Compressed Air System Specialist (CCASS) certification test! It’s been a wild ride getting here, and I want to take you through my journey, to show what this certificate means to me.

Why CCASS? Six and a half years ago, I started my fascination with compressed air products and systems—how they power so much of modern industry, from manufacturing to automation. But I’ll be honest: there’s a lot to learn, and I wanted a way to prove I really get it. That’s where the CCASS certification came in. Offered by CAGI, it’s a credential that shows you’ve mastered the ins and outs of compressed air systems—think system design, energy efficiency, and all the components that make it tick. For me, it was about more than just a title; it was a chance to level up my skills and help customers optimize their systems.

The CCASS exam isn’t a walk in the park—it’s 80 multiple-choice questions in just 1.5 hours, testing your applied knowledge, skills, and abilities. CAGI doesn’t hand you a study guide, but they do point you to some resources. Their “Body of Knowledge” list was my starting point, packed with references like the Compressed Air & Gas Handbook and standards like ASME EA-4 for energy assessments. I dove into those, soaking up everything from compressor basics to sustainability tips.

What does this mean? Well, I’m the 6th person on the application engineering team to become certified. Our team of Application Engineers are dedicated to continuous self-improvement and actively seek ways to assure our readers, clients, and prospective customers that we are the foremost authorities in engineered solutions for point-of-use compressed air. We prioritize ongoing education and share our expertise through various platforms. This includes informative blogs like this one, casual videos available on our YouTube Channel and website, articles in different publications, and our webinars.

The subjects we cover range from strategies to reduce waste associated with one of the most costly utilities to system designs that mitigate pressure drops and ensure adequate supply for point-of-use applications. We can provide both in-depth analysis and high-level overviews to cater to different levels of understanding.

If you wish to evaluate our expertise or learn more about how we can assist with your facility’s compressed air needs, please reach out to an Application Engineer today.

Jordan Shouse, CCASS

Application Engineer

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Twitter: @EXAIR_JS

Intelligent Compressed Air: Air Compressor Isentropic Efficiency

Published on by Russ BowmanLeave a comment

If you’re reading the EXAIR blog, odds are you’re interested in getting the most out of your compressed air system. While using engineered compressed air products is certainly one of the best ways to do that (see our Six Steps To Optimizing Your Compressed Air System), there are some things you can look at on the supply side as well. One such metric – and a key one, at that – is isentropic efficiency.

In a nutshell, isentropic efficiency is a measure of how well an air compressor converts the electrical energy it consumes into compressed air. The basic formula is a ratio between the compressor’s actual performance to that of an ideal compression process. Mathematically, it’s expressed as:

Now, as long as air compressors have moving parts, the actual energy consumed will always be higher than the amount of energy required for an ideal process. That’s because the ideal process ignores inescapable losses due to friction between – and inertia of – moving parts, electrical losses (motor efficiency), pressure drops, and heat of compression. So, like any other machine or engine, you’ll never get 100% efficiency.

It’s still a great idea to look for the highest efficiency. So great, in fact, that the U.S. Department of Energy, just this month, began efficiency regulation for oil-flooded rotary air compressors, meaning these compressors will have to meet minimum standards of isentropic efficiency. Specific Power used to be the standard by which an air compressor’s efficiency would be evaluated. It’s the ratio of power consumption to the amount of compressed air produced, normally expressed as kW/100CFM. That doesn’t take the compressor discharge pressure into consideration, which does indeed affect the power needed to generate a given amount of compressed air. We know that a 2psi pressure change will result in a 1% change in power consumption. So, if one manufacturer reports the Specific Power as kilowatts per 100 CFM @100psig, and another reports it as kilowatts per 100 CFM @140psig, that 40psi difference means a 20% variance.

Now, that doesn’t mean we stop using Specific Power – it’s one of the two variables in the isentropic efficiency equation. The other being, of course, the discharge operating pressure:

Where:

  • 16.52 and 0.2857 are constants
  • p2 is the discharge operating pressure (psig)
  • 14.5 is atmospheric pressure (psi) – this corrects gauge pressure to absolute pressure
  • P2 is Specific Power

The Compressed Air & Gas Institute (CAGI) publishes data sheets that are analogous to the fuel efficiency stickers on new car windows. Here’s a sample of one:

And, using the isentropic efficiency formula:

We get an isentropic efficiency of 86.50% (close enough to the CAGI Data Sheet’s 86.47%; likely due to a significant figure discrepancy in the calculations), which is pretty good. The highest published isentropic efficiency is about 92%. At EXAIR, our mission is to help you get the most out of our products and your compressed air system. If you have questions, we’ve got answers – give me a call.

Russ Bowman, CCASS

Application Engineer
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Compressed Air and Pressure Drop: Explained

Published on by Tyler DanielLeave a comment

A critical component to optimal performance of any compressed air operated product is ensuring sufficient compressed air flow. Simply put, inadequate air flow won’t allow you to get the job done.

 As compressed air moves through the distribution system, it encounters friction inside the walls of the pipe, tube, hose, etc. The diameter of the pipe, length, number of direction changes, and finished surface of the inner wall all play a part in this. A drop in air pressure will occur as a result of this friction. In addition to pressure drops experienced due to the distribution system, they can also occur at the point of use. If the line is undersized, this pressure drop will be great enough to impact the performance of the product. 

When designing and maintaining your compressed air system, pressure measurements should be taken at varying points to identify (and fix) any issues before they create a greater problem down the road. According to the Compressed Air Challenge, these are the places you should take regular pressure measurements to determine your system operating pressure:

  • Inlet to compressor (to monitor inlet air filter) vs. atmospheric pressure
  • Differential across air/lubricant separator
  • Inter-stage on multistage compressors
  • After-cooler
  • At treatment equipment (dryers, filters, etc.)
  • Various points across the distribution system
  • Check pressure differentials against manufacturers’ specifications. If high pressure drops are noticed, this indicates a need for service.

*More recent compressors will measure pressure at the package discharge, which will include the separator and after-cooler.

Once you’ve taken these measurements, simply add the pressure drops measured and subtract that value from the operating range of your compressor. That figure is your true operating pressure at the point of use.

If your distribution system is properly sized and the pressure drops measured across your various equipment are within specifications, any pressure drop noticed at the point of use is indicative of an inadequate volume of air. This could be due to restrictive fittings or undersized air lines, hose, or tube. Check that the point of use product is properly plumbed to compressed air per the manufacturer’s specifications.

EXAIR Products are designed to minimize this pressure drop by restricting the flow of compressed air. The more energy (pressure) that we’re able to bring to the point of use, the more efficient and effective that energy will be. The photo below shows two common examples of inefficient compressed air usage. With an open-ended blow off, a pressure drop occurs upstream inside the supply line. If you were to measure the pressure directly at the point of use, while in operation, you’d find that the pressure is significantly lower than it is at the compressor or further up the line. In the other photo with a modular style hose, some pressure is able to build up but if it gets too high the hose will blow apart. These types of modular style hose are not designed to be used with compressed gases.

EXAIR’s Super Air Nozzles, on the other hand, keep the compressed air right up to the point of discharge and minimize the pressure drop. This, in addition to the air entrainment, allows for a high force while maximizing efficiency. If you’d like to talk about how an EXAIR Intelligent Compressed Air Product could help to minimize pressure drop in your processes, give us a call.

Tyler Daniel, CCASS

Application Engineer

E-mail: TylerDaniel@EXAIR.com

X: @EXAIR_TD