Tag: six steps

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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Six Steps to Optimizing:  Step 1 – Measure the Air Consumption

Published on by John BallLeave a comment

Since air compressors use a lot of electricity to make compressed air, it is important to use the compressed air as efficiently as possible. EXAIR has six simple steps to optimize your compressed air system. Following these steps will help you to cut electrical costs, reduce overhead, and improve your bottom line. In this blog, I will cover the first step – Measuring the air consumption to find sources that use a lot of compressed air.

Six Steps to Optimizing Your Compressed Air System

Information is important to diagnose wasteful and problematic areas within your compressed air system. To measure air consumption, flow meters are used to find the volume or mass of compressed air per unit of time. Flow rates are very useful data points to find problems like leaks, over-use in blow-offs, waste calculations, and comparison analysis.

There are many different types of flow meters. Many of them entail a breakdown of your current compressed air lines by cutting, welding, or dismantling for installation. This will add costs in downtime and maintenance staff. But, not with the EXAIR Digital Flowmeters. In this blog, I will share the features and benefits of the Digital Flowmeters, including options for you to start measuring and optimizing your compressed air system in Step 1.

Overall, it only takes a few minutes to install and start measuring. The installation kit comes with a drill guide to properly locate the two holes in the pipe. The Digital Flowmeter uses a clamp to mount onto the pipe and to seal the area around the probes. Once it is powered, the unit is ready to measure the air flow inside the pipe with a large LED display. The display can be customized to show flow readings in three different units; SCFM, M3/hr or M3/min; and, it can display the Daily Usage and Cumulative Usage. 

To get started, the EXAIR Digital Flowmeter is a thermal dispersion device that can accurately measure compressed air flows. They use two sensing probes for comparative analysis. One probe is a temperature sensing probe, and the other is a flow-sensing probe. By comparing these, the Digital Flowmeter can measure precisely the mass of air flow without needing to be re calibrated. They are a cost-effective, accurate, and simple way to measure compressed air flow.

EXAIR stocks a large volume of Digital Flowmeters to ship on the same day for U.S. and Canadian customers. We also offer a 30-day unconditional guarantee to try them out. We stock meters for pipe diameters from ½” NPT to 4″ NPT Schedule 40 black pipe. EXAIR can also offer flow meters up to 8″ NPT black pipe; copper pipes with diameters from 3/4″ to 4″, and aluminum pipes with diameters ranging from 40mm to 101mm. If you have another type of piping for your compressed air system, you can give us the material, O.D. or I.D., and wall thickness. We may still be able to get a Digital Flowmeter for you.

For measuring, all the units come standard with a 4 – 20mA analog output. Per your request, we can change this signal to a serial output for RS-485 or Ethernet connections. What more can we offer with the EXAIR Digital Flowmeter? Options. Options upgrade the flow meters to better suit your application. Here is a list below:

EXAIR’s Digital Flowmeter w/ USB Data Logger

USB Data Logger: This option allows for a recording of the flow information. With a software download, you can set up the USB Data Logger to record the flow from once a second (roughly 9 hours of storage) to every 12 hours. After the data points are recorded, you can then download the information into the software to review. Then the information can be uploaded to an Excel program to do further analysis.

Summing Remote: With compressed air pipes running along the ceiling and walls, reading the Digital Flowmeter may be difficult. The Summing Remote has a 50-foot (15 meter) cable to bring the LED display into viewing. The Summing Remote is powered by the Digital Flowmeter, and it can be positioned at eye level, inside managers’ rooms, or around large equipment for monitoring.

Hot Tap Digital Flowmeter: This option is a great way to install a Digital Flowmeter on the pipe without shutting down the compressed air line. We offer this option for 2″ and larger for steel and copper pipes. It gives a quick and easy way to attach them if you have a 24-hour operation or a critical process that needs to run continuously.

Pressure Sensing Digital Flowmeter: If you would like to know the compressed air flow and the air pressure, this option will be able to do this. They are available with the Digital Flowmeters for steel and copper pipes that are 2″ and larger, and for the aluminum piping that is 50mm and larger. This option can display pressure units in either PSI or Bar right on the same LED display that shows the flow readings.

Block-Off Rings: If you want to move your Digital Flowmeter, the Block-Off Rings will be able to cover the openings in your compressed air pipe. They seal around the drilled opening when the Digital Flowmeter is removed from the pipe. They are reusable; so, they can be removed if you want to remount the Digital Flowmeter in the same spot. If you want to use one flow meter in different locations, the Block-Off Rings allow you to do this.

When you need to analyze your pneumatic components, flow is an important point in diagnosing the overall “health” of your compressed air system. The EXAIR Digital Flowmeter can give you that important data point. With optimization, you can cut your energy consumption, improve efficiency, and save yourself money. This blog is an overview of Step 1 of six steps. You may have more questions about the other steps, and that is great! You can find them in other EXAIR blogs, or you can contact an Application Engineer at EXAIR.

John Ball
Application Engineer
Email: johnball@exair.com
Twitter: @EXAIR_jb

Optimizing Compressed Air: 6th Step – Lower the Pressure!

Published on by Tyler DanielLeave a comment

The last step in EXAIR’s Six Steps to Optimizing Your Compressed Air System centers around air pressure. Unless you’re controlling your air pressure for each individual application, there’s a strong chance you can achieve quite a bit of savings by lowering the air pressure just upstream.

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. As the last of the six steps to optimizing your compressed air system, controlling air at the point of use can often be overlooked.

Pressure Regulators “dial in” performance to get the job done without using more air than necessary.

Pressure regulators utilize a control knob that is turned to either increase/decrease tension on a spring. The spring puts a load on the diaphragm which separates internal air pressure from the ambient pressure. Typically made of a flexible rubber material, these diaphragms react very quickly to changes in the air supply. By either increasing or decreasing the flow of air based on the load on the diaphragm, downstream pressure remains fairly constant.

While one advantage of a pressure regulator is certainly maintaining consistent pressure on 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 recommends operating your Intelligent Compressed Air Products at the minimum pressure necessary to achieve a successful application. If you notice a desirable result at a pressure of 60 PSIG, or even less, there’s no need to run full line pressure. In-line point of use pressure regulators are the simplest and most reliable way to allow you to dial down the pressure for any compressed air operated product.

When selecting a pressure regulator for your application, it’s critical that it is appropriately sized to supply adequate volume to the point of use devices downstream. Doing so, minimizes the risk of experiencing “droop”. Droop is a decrease in outlet pressure from the specified setting due to an increase in flow rate.  Droop occurs when the demand at the point of use exceeds the volume of air that the regulator can supply. By ensuring the pressure regulator is rated to deliver a sufficient volume of air, you’ll reduce the chances of experiencing droop. EXAIR offers pressure regulators in kits along with many of our products. We’ve done the hard part for you and made sure they’re properly sized!

If you’re looking for ways to help lessen the demand on your compressor, EXAIR’s team of Application Engineers will be happy to help. Reach out to us via phone, chat, or e-mail and see for yourself just how easy it can be to start saving compressed air!

Tyler Daniel, CCASS

Application Engineer

E-mail: TylerDaniel@EXAIR.com

Twitter: @EXAIR_TD

Hot Off The Press (Release): EXAIR Catalog #35

Published on by Russ BowmanLeave a comment

If you’re a registered user on our website, you likely got word of this already through our August 15, 2023 Press Release. If not – or even if you did and want some more details – read on, and I’ll tell you all about it.

Like all of our previous catalogs, Catalog #35 provides specification, dimensional, and performance data on all of our stock products. Many of them include detailed descriptions of “textbook” applications for those products. You’ll also find:

  • Efficiency Lab (page 6): If you want a full performance report on a compressed air device you’re using right now, this is a free service we offer. Contact an Application Engineer and arrange to have it sent in. We’ll test it for compressed air consumption, force applied, and sound level, and send you a report on it. It’ll include, of course, the EXAIR engineered product(s) that we’ll recommend, along with performance data on them, as a comparison.
  • Our Six Steps (page 7): The first page of our Optimization section details the Six Steps To Optimizing Your Compressed Air System. It’s not necessary to follow them in order, and not all of them are applicable to every single compressed air system. But if you’re serious about reducing your compressed air costs, this is a comprehensive plan on how to do it for sure.
  • OSHA Maximum Allowable Noise Exposure table & typical Air Consumption values of common “homemade” blow offs (page 53): We put this here so you can turn the next few pages and see what a difference engineered products like EXAIR Super Air Nozzles can make.
  • Droplet Size data (page 98): Use this to determine the suitability of our Atomizing Spray Nozzles for liquid spraying applications.
  • Vortex Tube Specification and Performance tables (pages 201-202): If you know how much cold air flow you need, and at what temperature you need it, you can use these tables to determine which EXAIR Vortex Tube (or other Spot Cooling Product) to use.
  • Cabinet Cooler System Sizing Guide (page 220): Just fill in the blanks & send this in, and we’ll quickly & accurately calculate the heat load of your electrical/electronic enclosure, and specify the right Cabinet Cooler System for you.

Now, if you’ve ever had any of our previous catalogs, you might have noticed that those were already in there, and that’s all pretty great. What’s REALLY great about Catalog #35, though, is some of the new features:

  • Line Vac Conveyance Data (pages 176-177): While there’s WAY too many variables in bulk conveyance applications to accurately calculate conveyance rates. We’ve done some controlled, in-house testing with several different materials, several different Line Vacs, at several different lengths & heights, though, and we’re proud to publish that in the new catalog. This shouldn’t be considered a guarantee of performance, but if you’re wondering how much of a particular bulk material you can convey, this table will certainly get you in the right ballpark.
  • Best Practice for Using EXAIR Intelligent Compressed Air Products (pages 239-240): This information has always been in the Air Data files on our website, along with an ABUNDANCE of data that’ll help you get the most out of your compressed air system. Now, it’s at your fingers.

Of course, I’d be remiss if I wrote a whole blog on the new catalog without mentioning the new products:

  • Model 9207 Ultrasonic Leak Detector (pages 18-19): This serves the same function as the now-obsolete Model 9061, but with some handy upgrades like a LED display, a sleek new body, and high quality ear buds.
Use the Model 9207 Ultrasonic Leak Detector’s parabola to find the vicinity of the leak, and the tubular extension to identify its exact location.
  • 1/2 NPT HollowStream Cone Atomizing Nozzles (page 105): With five new distinct models at the high-flow end of our already comprehensive line of Liquid Atomizing Spray Nozzles, these provide up to 53 gallons per minute of liquid flow, and are capable of passing particulate up to 0.344″ in diameter.
The Hollow Cone spray pattern is ideal for cooling, cleaning, foam breaking, rinsing, and dust suppression. It also uses considerably less liquid than the OmniStream models, when higher flow rate isn’t necessary.
EXAIR’s ATEX Cabinet Cooler Systems provide heat protection for electrical enclosures in potentially explosive atmospheres, like those found on offshore drilling platforms, petrochemical plants, mines, flour mills, etc.

Like our previous catalogs, Catalog 35 is now available for download (in product line sections due to file size) from the PDF Library at EXAIR.com. You can also request a copy to be mailed to you, or you can contact an Application Engineer to have individual product line sections (again, because of file size) email to you right away.

As always, if you’d like to talk about how to get the most out of your compressed air system, our team of Application Engineers are here Monday to Friday, 7am to 4pm Eastern, to help with that. Give me a call.

Russ Bowman, CCASS

Application Engineer
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