I recently recommended to a customer to turn their air pressure down on their system as low as their process would allow. Meaning regulate the pressure so you have enough to complete the operations needed but find that happy medium where your compressor isn’t working as hard to build those high pressures for no reason!
Compressed air is an amazing tool to have, and when used properly it can be more efficient that other non compressed air tools that run off electricity. How ever its pretty common to see compressed air systems running at their max just because.
Lowering the air system pressure reduces the compressor power consumption by about 1% for every two psi of lower pressure. Lowering the pressure also makes any unregulated operations reduce consumption by almost 1% for every one psi of pressure reduction. Not to mention the extra savings if your compressor system can turn down the compressor power because of the reduced flow and possibly shut off compressors that are no longer needed!
The best pressure at which to set your system is the level where your production can operate efficiently and effectively without waste: There is no right pressure—it depends on your operations and tools. You may have 90 to 100 psig at the compressor, but at the production machine, where the actual work is being done, you could have only 65 to 70 psig. In some cases, it may be even lower due to pressure drops in undersized piping, filters, regulators. The goal is to lower compressor discharge pressure without affecting the the operations at the end of the line.
Having artificially high plant-pressure can help you deal with surges in compressed air demand that might occasionally cause low-pressure and affect production. The higher pressure acts to store reserve air in the various volumes made up of receivers, pipes and such in your system. However, the higher pressure costs more to produce and makes unregulated end uses consume more air, which is an expensive trade-off. Another option is to make sure you have line pressure regulators at each point of use. This will allow you to regulate the operation to the pressure needed being sure to save compressed air and keep the over all system running more efficient.
If you look at operating costs alone, compressed air can be just about the most inefficient method there is for cleaning parts. If you just look at the risks, it’s potentially very dangerous too. Don’t even get me started on the insufferable noise it can make.
For cleaning parts, most folks are familiar with the use of an air gun. You can find the simplest of these in many industrial settings: a valve (often in the form of a handheld trigger device) fitted with a nozzle of some sort (often in the form of an open ended tube, pipe, or fitting to focus or direct the air flow). These have all three of the “downsides” I opened this blog with. Of course, these concerns can be mitigated to a high degree by using the right tool for the job. That’s where engineered products like EXAIR Safety Air Guns come in. Let’s look at how we can address these three “downsides”:
Efficiency: This is all about compressed air consumption. In the simplest of air guns mentioned above, consumption is only limited by the passages in the valve (or trigger) and the discharge fitting…and those limits are usually negligible. Modifying the ends (see examples below) to focus the air flow usually has minimal effect, because you’re not appreciably changing the total cross sectional area of the discharge opening:
Safety: Remember learning about kinetic and potential energy in grade school? Well, when you compress air to 100psig, fitting all that air into a much smaller space creates a TREMENDOUS amount of potential energy:
One problem with the thumb guns above is, if you were to jam into the palm of your hand and pull the trigger, a large component of that potential energy (pressure) turns into kinetic energy (force)…more than enough to break the skin and cause a potentially fatal condition known as an air embolism. In the United States, OSHA (Occupational Safety and Health Administration) regulates compressed air devices used for cleaning purposes. All EXAIR Safety Air Guns comply with Standard 1910.242(b) by providing a relief path to ensure that it cannot be dead ended, and thus never create over 30psi measurable at the outlet)
Noise: Another problem is, another component is turned into sound pressure…discharging air from a direct opening is quite loud. OSHA standards address these with limitations on outlet pressure and sound level. All EXAIR Safety Air Guns comply with Standard 1910.242(b), which limits the outlet pressure (by providing a relief path to ensure that it cannot be dead ended, and thus never create over 30psi measurable at the outlet) and all but our largest Super Blast Safety Air Guns comply with Standard 1910.95(a) limits for continuous 8 hour sound level exposure.
Which brings us to the topic of this blog: How exactly did THEY (our customer who used to use the thumb guns above) select the right Safety Air Gun, and how can we apply that to getting the right Safety Air Gun for YOU?
These steps aren’t all-inclusive, and they don’t necessarily need to be followed in order, but if you call an EXAIR Application Engineer about selecting a Safety Air Gun, here’s what we’re gonna talk about:
Airflow pattern: Honestly, I could make a good case for this being the first consideration. Selection of any blowoff product – be it an Air Nozzle, Air Amplifier, Air Knife, Air Wipe, etc., will largely depend on the size and shape of the airflow.
For the most precise, focused blowoff, our Atto Super Air Nozzle (top left) is a great choice. It’s available on:
When stubborn, heavy, and/or LOTS of debris needs to be absolutely, positively blown off RIGHT NOW, our High Force Super Air Nozzles may be just what you need. Our largest; Model 1120 1-1/4 NPT Super Air Nozzle, is shown (above right). The High Force Super Air Nozzles are offered on:
Soft Grip or Heavy Duty Safety Air Gun (up to 3.3 pounds of force over a 6.3″ wide area @12″ away)
Application specific concerns: Everything we’ve discussed so far has involved aiming the blow off stream away from the operator, in the direction the device is aimed. In addition to wide variety of engineered Air Nozzles, EXAIR offers a number of options for these products:
If you’re looking for a portable, hand-held compressed air blow off product that’s quiet, safe, and efficient, look no further than EXAIR Corporation’s extensive line of Safety Air Guns. If you’d like to find out more, give me a call.
Russ Bowman, CCASS
Application Engineer EXAIR Corporation Visit us on the Web Follow me on Twitter Like us on Facebook
Fluid mechanics is the field that studies the properties of fluids in various states. There are two main areas; fluid statics and fluid dynamics. Fluid dynamics studies the forces on a fluid, either as a liquid or a gas, during motion. Osborne Reynolds, an Irish innovator, popularized this dynamic with a dimensionless number, Re. This number determines the state in which the fluid is moving; either laminar flow, transitional flow, or turbulent flow. Equation 1 below shows the relationship between the inertial forces of the fluid as compared to the viscous forces.
Equation 1: Re = V * Dh/u
Re – Reynolds Number (no dimensions)
V – Velocity (feet/sec or meters/sec)
Dh – hydraulic diameter (feet or meters)
u – Kinematic Viscosity (feet^2/sec or meter^2/sec)
The value of Re will mark the region in which the fluid (liquid or gas) is moving. If the Reynolds number, Re, is below 2300, then it is considered to be laminar (streamline and predictable). If Re is greater than 4000, then it is considered to be turbulent (chaotic and violent). The area between these two numbers is the transitional area where you can have eddy currents and some non-linear velocities. To better show the differences between each state, I have a picture below that shows water flowing from a drain pipe into a channel. The water is loud and disorderly; traveling in different directions, even upstream. With the high velocity of water coming out of the drain pipe, the inertial forces are greater than the viscous forces of the water. This indicates turbulent flow with a Reynolds number larger than 4000. As the water flows into the mouth of the river, the waves transform from a disorderly mess into a more uniform stream. This is the transitional region. A bit further downstream, the stream becomes calm and quiet, flowing in the same direction. This is laminar flow. Air is also a fluid, and it will behave in a similar way depending on the Reynolds number.
Why is this important to know? In certain applications, one state may be better suited than the other. For mixing, suspension and heat transfer; turbulent flows are better. But, when it comes to effective blowing, lower pressure drops and reduced noise levels; laminar flows are better. In many compressed air applications, the laminar region is the best method to generate a strong force efficiently and quietly. EXAIR offers a large line of products, including the Super Air Knives, Super Air Amplifiers and Super Air Nozzles that utilizes that laminar flow for compressed air applications. If you would like to discuss further how laminar flows could benefit your process, an EXAIR Application Engineer will be happy to help you.
How many times have you purchased a new product and worried if it was the right choice? Well EXAIR can provide that confidence using our calibrated testing equipment to compare your current product to an EXAIR product, in our Efficiency Lab. Whenever I needed a new process or product I would spend countless hours researching how will this benefit me, my employer or my customer? Research is not only time consuming but also very costly.
EXAIR believes in their product so much that we offer an Efficiency Lab where we will test your production product and help show that our products will not only work for you, but also show that they can save money, as well as make your work environment a safer place.
EXAIR has provided performance values (force, noise, air consumption, ROI) for many of our products. We make purchasing from EXAIR fun because you know in advance that our products will meet or exceed your expectations. Further backing up our commitment with the Efficiency Lab we offer an 30 Day Unconditional Guarantee. EXAIR believes in our products and want to make your purchase a risk free process.
We can test the performance of your current product to EXAIRs Intelligent Compressed Air products for air consumption, force, noise levels… and provide a comprehensive report of our analysis, including simple ROI.
What does our Efficiency Lab cost? EXAIR believes in our products so much, that this is a free service to our customers. Simply call and talk to one of our Application Engineers at 800.903.9247 or you can send an email to firstname.lastname@example.org or visit www.exair.com and talk on our live help. If you feel we can help with a comparison them simply send your product(s) freight prepaid to EXAIR Corporation attention to our Efficiency Lab. All trials will be on a confidential basis unless you provide permission to share.