Fluidics is an interesting discipline of physics. Air, in particular, can be made to behave quite peculiarly by flowing it across a solid surface. Consider the EXAIR Standard and Full Flow Air Knives:
If you’ve ever used a leaf blower, or rolled down the car window while traveling at highway speed, you’re familiar with the power of a high velocity air flow. Now consider that the Coanda effect can cause such a drastic redirection of this kind of air flow, and that’s a prime example of just how interesting the science of fluidics can be.
As fascinating as all that is, the entrainment of air that these products employ contributes to another principle of fluidics: the creation of a boundary layer. In addition to the Coanda effect causing the fluid to follow the path of the surface it’s flowing past, the flow is also affected in direct proportion to its velocity, and inversely by its viscosity, in the formation of a boundary layer.
This laminar, lower velocity boundary layer travels with the primary air stream as it discharges from the EXAIR products shown above. In addition to amplifying the total developed flow, it also serves to attenuate the sound level of the higher velocity primary air stream. This makes EXAIR Intelligent Compressed Air Products not only as efficient as possible in regard to their use of compressed air, but as quiet as possible as well.
If you’d like to find out more about how the science behind our products can improve your air consumption, give me a call.
So, you’ve selected a quiet, efficient, and safe EXAIR Super Air Nozzle for your blow off application – good call! – and now you’re thinking about how to install it. Sometimes, it’s as simple as replacing whatever you’re using right now:
Or maybe you’re using an open end blow off…in which case, you’re just an adapter away:
Perhaps, though, it’s a new installation, or the existing supply lines aren’t suitable for one reason or another. In those cases, we’ve still got you covered…consider the EXAIR Stay Set Hose:
Available in a variety of lengths from 6″ to 36″, they’re positionable, and re-positionable with a simple bending action. They won’t kink or easily fatigue like copper tubing. The supply end is 1/4 MNPT, and you have your choice of 1/4 MNPT or 1/8 FNPT on the other end, depending on which Super Air Nozzle, Air Jet you need to use it with.
We also offer Blow Off Systems, which are a combination of a specific Air Nozzle (or Air Jet,) fitted to a Stay Set Hose:
For added convenience and ease of installation, these products can also come with a Magnetic Base:
From the beginning in 1983, EXAIR’s focus has been on being easy to do business with, and that goes from our friendly customer service to our expert technical support to our 99.9% on-time shipments (22 years and running) to designing our engineered products and value-added accessories with efficiency, safety, and ease of installation in mind. If you want to find out more, give me a call.
Over the last few months, my EXAIR colleagues and I have blogged about several different types of air compressor types including single and double acting reciprocating,rotary screw and sliding vane air compressors. You can click on the links above to check those out. Today, I will review the basics of the rotary scroll-type compressor.
The rotary scroll type compressor falls under the positive displacement-type, the same as the other types previously discussed. A positive displacement type operates under the premise that a given quantity of air is taken in, trapped in a compression chamber and the physical space of the chamber is mechanically reduced. When a given amount of air occupies a smaller volume, the pressure of the air increases.
Each of the previous positive displacement type compressors use a different mechanism for the reduction in size of the compression chamber. The rotary scroll uses two inter-meshing scrolls, that are spiral in shape. One of the scrolls is fixed, and does not move (in red). The other scroll (in black) has an “orbit” type of motion, relative to the fixed scroll. In the below simulation, air would be drawn in from the left, and as it flows clockwise through the scroll, the area is reduced until the air is discharged at a high pressure at the center.
It is of note that the flow from start to finish is continuous, providing air delivery that is steady in pressure and flow, with little or no pulsation.
There is no metal to metal sliding contact, so lubrication is not needed. A drawback to an oil free operation is that oil lubrication tends to reduce the heat of compression and without it, the efficiency of scroll compressors is less than that of lubricated types.
The advantages of the rotary scroll type compressor include:
Comes as a complete package
Comparatively efficient operation
Can be lubricant-free
The main disadvantage:
A limited range of capacities is available, with low output flows
EXAIR recommends consulting with a reputable air compressor dealer in your area, to fully review all of the parameters associated with the selection and installation of a compressed air system.
If you would like to talk about compressed air or any of the EXAIR Intelligent Compressed Air® Products, feel free to contact EXAIR and myself or one of our Application Engineers can help you determine the best solution.
There are some very good reasons to consider an EXAIR compressed air operated Industrial Housekeeping Product for liquid applications:
*Durability. No moving parts means nothing to wear or get damaged.
*Safety. No electricity means no dragging an energized cord through a wet area.
*Convenience. All you need is a supply of compressed air.
*Reliability. If you supply it with clean, dry air, it’ll run darn near indefinitely, maintenance free.
Depending on the needs of the application, we have different models to choose from:
Reversible Drum Vacs
If you’ve got a closed top steel drum that’s in good condition, look no further than the Reversible Drum Vac System. It comes with everything you need to turn that drum into a powerful, 2-way liquid pumping system. This is great if you just need to park the drum in one spot and suction out a sump or tank on a regular basis, using its 10 foot Vacuum Hose & Suction Wand. They’re in stock for your existing 30, 55, and 110 gallon drums. A 5 Gallon Mini Reversible Drum Vac System is also available; it includes the drum as well.
If you’d like a little mobility, and a way to clean up floor spills, then the Deluxe Reversible Drum Vac System might be what you’re looking for. It adds a Drum Dolly and our Spill Recovery Kit…it consists of a floor-length wand and a dual squeegee tool. It also comes with a set of plastic tools (crevice tool, small skimmer, and two 20″ extensions) and a Tool Holder with clips for the tools, and magnets to attach to the drum. We keep them in stock for your existing 30 and 55 gallon drums. It also comes in the 5 Gallon Deluxe Mini Reversible Drum Vac System(drum included.)
For a complete system, the Premium Reversible Drum Vac Systems have everything you need for most any liquid drum transfer job: they add a drum, lid & latch ring, as well as a compressed air supply hose & shutoff valve, and an upgrade to Heavy Duty Aluminum Tools. They’re available with 30, 55, or 110 gallon drums; in stock.
Any of the 30, 55, or 110 Gallon systems are also available with our High Lift Reversible Drum Vac. These provide for increased performance with more viscous liquids, and/or when the liquid needs to pumped from a depth of up to 15 feet. They are outfitted identically to the standard Reversible Drum Vac Systems, except they come with a 20 foot Vacuum Hose.
As versatile as the Reversible Drum Vacs are, we also incorporate them into another 2-way pumping system, designed to help you get maximum life and performance from machine tool coolant and cutting oils: The award-winning Chip Trapper Systems.
Powered by the Reversible Drum Vac, the Chip Trapper System draws the incoming liquid into the drum through a Filter Bag, which retains (or “traps”) any particulate as the drum fills with liquid. Then, the freshly filtered liquid can be immediately pumped back out, while the particulate remains in the bag. Once the bag is full, simply remove the drum lid, unhook the bag, empty it out, and return it to service. The Chip Trapper System comes with two Filter Bags, in fact, so you can clean one while you use the other. They are available, from stock, in 30, 55, and 110 gallon sizes. They are all three available in High Lift configuration as well, with a 20 foot Vacuum Hose.
“To measure is to know – if you cannot measure it, you cannot improve it.” -Lord Kelvin, mathematical physicist, engineer,and pioneer in the field of thermodynamics.
This is true of most anything. If you want to lose weight, you’re going to need a good scale. If you want to improve your time in the 100 yard dash, you’re going to need a good stopwatch. And if you want to decrease compressed air consumption, you’ll need a good flowmeter. In fact, this is the first of six steps that we can use to help you optimize your compressed air system.
There are various methods of measuring fluid flow, but the most popular for compressed air is thermal mass air flow. This has the distinct advantage of accurate and instantaneous measurement of MASS flow rate…which is important, because measuring VOLUMETRIC flow rate would need to be corrected for pressure in order to determine the true compressed air consumption. My colleague John Ball explains this in detail in a most excellent blog on Actual (volume) Vs. Standard (mass) Flows.
So, now we know how to measure the mass flow rate. Now, what do we do with it? Well, as in the weight loss and sprint time improvements mentioned earlier, you have to know what kind of shape you’re in right now to know how far you are from where you want to be. Stepping on a scale, timing your run, or measuring your plant’s air flow right now is your “before” data, which represents Step One. The next Five Steps are how you get to where you want to be (for compressed air optimization, that is – there may be a different amount of steps towards your fitness/athletic goals.) So, compressed air-wise, EXAIR offers the following solutions for Step One:
Digital Flowmeter with wireless capability. This is our latest offering, and it doesn’t get any simpler than this. Imagine having a flowmeter installed in your compressed air system, and having its readings continually supplied to your computer. You can record, analyze, manipulate, and share the data with ease.
Digital Flowmeter with USB Data Logger. We’ve been offering these, with great success, for almost seven years now. The Data Logger plugs into the Digital Flowmeter and, depending on how you set it up, records the flow rate from once a second (for about nine hours of data) up to once every 12 hours (for over two years worth.) Pull it from your Digital Flowmeter whenever you want to download the data to your computer, where you can view & save it in the software we supply, or export it directly into Microsoft Excel.
Summing Remote Display. This connects directly to the Digital Flowmeter and can be installed up to 50 feet away. At the push of a button, you can change the reading from actual current air consumption to usage for the last 24 hours, or total cumulative usage. It’s powered directly from the Digital Flowmeter, so you don’t even need an electrical outlet nearby.
Digital Flowmeter. As a stand-alone product, it’ll show you actual current air consumption, and the display can also be manipulated to show daily or cumulative usage. It has milliamp & pulse outputs, as well as a Serial Communication option, if you can work with any of those to get your data where you want it.
Stay tuned for more information on the other five steps. If you just can’t wait, though, you can always give me a call. I can talk about compressed air efficiency all day long, and sometimes, I do!
My Application Engineer colleagues and I frequently use a handy table, called Discharge of Air Through an Orifice. It is a useful tool to estimate the air flow through an orifice, a leak in a compressed air system, or through a drilled pipe (a series of orifices.) Various tables and online calculators are available. As an engineer, I always want to know the ‘science’ behind such tables, so I can best utilize the data in the manner it was intended.
The table is frequently found with values for pressures less than 20 PSI gauge pressure, and those values follow the standard adiabatic formula and will not be reviewed here. The higher air pressures typically found in compressed air operations are of interest to us.
For air pressures above 15 PSI gauge the discharge is calculated using by the approximate formula as proposed by S.A. Moss. The earliest reference to the work of S.A. Moss goes back to a paper from 1906. The equation for use in this table is-Where:
For the numbers published in the table above, the values were set as follows-
C = 1.0, p1 = gauge pressure + 14.7 lbs/sq. in, and T1 = 530 °R (same as 70 °F)
The equation calculates the weight of air in lbs per second, and if we divide the result by 0.07494 lbs / cu ft (the density of dry air at 70°F and 14.7 lbs / sq. in. absolute atmospheric pressure) and then multiply by 60 seconds, we get the useful rate of Cubic Feet per Minute.
The table is based on 100% coefficient of flow (C = 1.0) For well rounded orifices, the use of C = 0.97 is recommended, and for very sharp edges, a value of C = 0.61 can be used.
The table is a handy tool, and an example of how we use it would be to compare the compressed air consumption of a customer configured drilled pipe in comparison to that of the EXAIR Super Air Knife. Please check out the blog written recently covering an example of this process.
If you would like to talk about the discharge of air through an orifice or any of the EXAIR Intelligent Compressed Air® Products, feel free to contact EXAIR and myself or one of our Application Engineers can help you determine the best solution.
If you’ve ever used an air gun to blow something off, you’re familiar with the cleaning ability of compressed air. If you can get the whole object blown off from where you’re standing, there really is no substitute…but what if you need to get to the other side…or sides?
This is where the EXAIR Super Air Wipe comes in…they allow you to blow a continuous, uniform 360° air stream, all around your product. Consider their benefits:
*Sizes: the Super Air Wipe’s compact ring design means it won’t take up a lot of room; you just need a few inches, in any direction, to install one. We stock them in eleven sizes, from 11″, all the way down to our brand-new 3/8″ diameter.
*Durability: All EXAIR Super Air Wipes are assembled with stainless steel shims and hardware. Models up to 4″ come with a rugged, stainless steel wire braided hose, connecting the two halves for compressed air supply.
*Ease of installation: Smaller sizes can be supported by the compressed air supply line, if a pipe is used and threaded into the connector hose’s 1/4 NPT port. Larger sizes can likewise be adequately supported with pipe to both halves. All models have a bolt circle of 1/4″-20 tapped holes for more permanent and rigid mounting. The split ring design is another key feature:
*Corrosion resistance: Depending on the environment in which the Super Air Wipe will be installed, we offer them with aluminum (3/8″ – 11″ sizes) or stainless steel (3/8″ – 4″ sizes) bodies.
*Temperature rating:Aluminum Super Air Wipes are good to 400°F (204°C) and stainless steel models are good to 800°F (427°C.)
*Range of operation: We install a 0.002″ thick shim in all stock Super Air Wipes; this is suitable for a wide range of typical industrial/commercial blow off applications…a Pressure Regulator can then be used to “dial in” the air flow precisely to meet specific needs. If a job calls for higher force & flow, additional 0.002″ shims can be installed. Shim Sets come with the Super Air Wipe Kits, or individual shims can be ordered separately.
*Performance: Before the Super Air Wipe, a ring of nozzles was commonly used. In fact, they still are, but we’re trying to fix that, at every opportunity we come across. Problem with those is, it’s hard to get an even air flow all around, which leads to inconsistent blow off. They can also be loud & inefficient, as we’ve found in numerous Efficiency Lab tests and Case Studies, like this one…
…and this one…
Do you have a challenging blow off application that you need help with? Call us to find out how an EXAIR Super Air Wipe (or another one of our Intelligent Compressed Air Products) can be a simple, quick & easy solution.