EXAIR Blogs This Week Are Almost As Cool As Shark Week

Yes, ALMOST. This week, the EXAIR Blog has featured some excellent explanations of the science behind the operation of compressed air products. On Tuesday, John Ball posted the best explanation of SCFM vs ACFM that I’ve come across, and I’ve been explaining this to callers for almost four years now. I’m using his blog to perfect my “elevator pitch” on this topic. It will still likely require a building with more than ten floors, but I think that’s OK.

Also on “Two Blog Tuesday,” (this week only; I’m not trying to start anything) Dave Woerner’s gem of a blog detailed the terminology associated with pressure measurement, and why we use “psig” (g = gauged) – in a nutshell, the compressed air inside the pipe doesn’t care what the pressure outside the pipe is. And, since he mentioned it, I might add that most of agree that we care even less about how a certain NFL team’s footballs were (or were not) properly inflated.

Brian Farno’s “One Blog Wednesday” entry was a quite useful (if not alphabetical…OK; now I AM trying to start something) list of some common terms and expressions we use on a regular basis while discussing the operation and performance of EXAIR compressed air products. If you liked his photo demonstration of the Coanda effect with the foam ball & Super Air Amplifier, I encourage you to experience the Coanda effect for yourself, if you have access to a leaf blower and a volleyball:

I mention these earlier blogs to get to the point of MY blog today…a bit of theory-to-practice, if you will. Once you’ve gotten a decent understanding of these principles (or have the above links bookmarked for quick reference,) we can apply it to what’s needed for the proper operation of a compressed air product itself.

With a working knowledge of air flow (SCFM) and compressed air supply pressure (psig,) we can more easily understand why certain pipe sizes are specified for use with particular products. For instance, the longer the Super Air Knife and/or the longer the run of piping to it, the larger the pipe that’s needed to supply it:

This table comes directly from the Installation & Operation Instructions for the Super Air Knife.

This table comes directly from the Installation & Operation Instructions for the Super Air Knife.

The reasons for this are two-fold: First, the pipe…longer runs of pipe will experience more line loss (a continuous reduction in pressure, due to friction with the pipe wall…and itself) – so, larger diameter pipe is needed for longer lengths. For another practical demonstration, consider how much faster you can drink a beverage through a normal drinking straw than you can through a coffee stirrer. Not as dramatic as the leaf blower & volleyball (you really want to try it now, don’t you?) but you get my point.

Second, the Air Knife…the longer the Air Knife, the more air it’s going to use. And, if it’s longer than 18”, you’ll want to feed it with air at both ends…line loss will occur in the plenum as well.

In closing, I want to leave with another video, shot right here at EXAIR, showing the actual reductions in pressure due to line loss through different lengths, and diameters, of compressed air supply line to a Super Air Knife.

If you ever have any questions about compressed air use, or how EXAIR products can help you use your compressed air more efficiently, safely, and quietly, please give us a call.

Russ Bowman
Application Engineer
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Nano Super Air Nozzle Removes Coolant From Die Casting

We take quite a few calls from customers looking for a nozzle that will provide more force than the current open ended pipe they are currently using. While we do offer nozzles that range in force from 2.0 ounces up to 23 lbs., sometimes force isn’t as important as is having a high velocity, depending on the application.

I recently worked with a customer who was wanting to blow machining coolant out of a blind hole in their aluminum die casting application. O the bottom of the part is an M10 tapped hole, 32mm deep and is running on a conveyor system that indexes to different stations. As the part indexes and goes over a transition, they were using an 1/8” open pipe, to blow up into the blind hole to remove coolant and any remaining debris hung up in the threads of the hole. While the open pipe was doing the job, they were needing a more efficient alternative with a small footprint to fit the application.

I recommended using our Model # 1110SS-NPT Nano Super Air Nozzle. The Nano Super Air Nozzle, produces 8.1 ounces force but also provides a high velocity, focused air stream. Compared to the open pipe, the unit consumes about 1/8 of the compressed air or only 8.3 SCFM @ 80 PSIG. (See below chart).

open blow air consumption

Inefficient Homemade Blowoffs

All of our nozzles take advantage of the Coanda effect to entrain the surrounding air, up to 25 times or more. The result is a high velocity, forceful airstream that requires a minimal amount of compressed air. As well as being OSHA compliant for 30 psi dead end pressure (cannot be dead ended) per Standard CFR 1910.242(b) and meeting the allowable noise exposure limits per Standard 29 CFR 1910.95(a).

If you have an application where you are needing to replace the unsafe, inefficient blowoffs in your facility, please contact an Application Engineer at 1-800-903-9247.

Justin Nicholl
Application Engineer
justinnicholl@exair.com
@EXAIR_JN

Cabinet Coolers in January?

Dual CC outside

Without putting too much thought into it, one might assume that January would not be Cabinet Cooler season. But actually, our friends in the southern hemisphere (Australia, New Zealand, South Africa, Argentina, Chile and Brazil) are experiencing their summer at the very same time that we in the mid-west of the United States have been having some bone-chilling cold weather blow in from Canada. Our New Zealand distributor told me just the other day that they were having 35°C days with water restrictions and everyone is on fire watch because it is so hot and dry right now.

As uncomfortable as that might be for the folks living there, many must continue their production in the un-air conditioned environments. And in doing so, they have to keep their machines up and running to maintain production. But the controls for those machines are not always so cooperative because the CPU is overheating or the inspection camera is giving out because it is too hot.

Where do they turn?  EXAIR of course. Once our distributor partner assists the customer with sizing and makes recommendation (sometimes with a little help from us). The customer installs the Cabinet Cooler System and has taken care of their overheating problem within the application once and for all.

The reason why I say “once and for all”, is that the Cabinet Cooler Systems have no moving parts and are virtually maintenance-free. There are no filters to constantly change due to dirty factory environments. And best of all, the Cabinet Cooler can continue to operate in the range of 20 years plus.

When you compare the small cost of a Cabinet Cooler System to that of down time, lost production and the cost to repair burnt out controls, it is truly an easy decision to make.

So, back to our friends in the Southern Hemisphere, where hot and dry is the order of the day, consider having an EXAIR Cabinet Cooler for your application today. Contact us in the International Application Engineering / Sales Department or consult our International Distributor Locator to find the distributor near to you.

Neal Raker, International Sales Manager
nealraker@exair.com

A (Sample) Lexicon For Compressed Air

Every industry and different technical subject matter comes with it’s own lexicon of terms or vocabulary words.  More often than not, when speaking to an Application Engineer here at EXAIR you are going to hear words within our lexicon. The list I have compiled below is merely a sampling to help translate some terms that we forget not everyone knows.  Some of these are merely acronyms that get thrown around a good amount.

SCFM – Standard Cubic Feet per Minute – This is the unit we use to represent the volumetric flow rate of compressed gas that has already been corrected to standardized conditions of pressure and temperature.

PSIG – Pounds per square inch gauge – This is the unit which we use to represent the operating inlet pressure of the device.  When requesting this, we generally are looking for a pressure gauge to be installed directly on the inlet to the device with no other form of restrictions between the two.  For the most part, catalog consumption values are given in SCFM at 80 psig.  The main exception to that rule are the Vortex Tube based products.

Compressed Air – This is a utility that most industrial manufacturing facilities have available to them.   It is regular, atmospheric air which has been compressed by an air compressor to a higher pressure than atmospheric.  Generally speaking, compressed air systems will be at a range of 85-120 psig.

OSHA – Occupational Safety and Health Administration – This is the main federal agency that enforces two of the major conformance standards that EXAIR products meet or exceed.

29 CFR- 1910.95 (a) – Maximum allowable noise level exposure.  The great majority of EXAIR products meet or exceed this safety standard, our largest Super Air Nozzles
1910.242 (b) – This is the standard which states compressed air blow off devices cannot exceed 30 psig of dead end pressure.  This means, if the exit point of the air can be blocked the operating pressure must be below 30 psig.  The reason for this standard is to prevent air embolism which can be fatal.  All EXAIR products meet or exceed this standard by having multiple orifice discharge.

Coanda Effect - This is the effect that numerous EXAIR products utilize to amplify and entrain ambient air.   The Coanda effect is when a fluid jet (stream of compressed air) tends to be attracted to a nearby surface.  This principle was found by a Romanian aerodynamics pioneer, Henri Coandᾰ.  The picture below shows a Super Air Amplifier blowing a foam ball into the air and suspending it due to the Coanda effect on the surface of the ball.

A Super Air Amplifier's air stream causes a foam ball to be suspended in mid air thanks to the Coandᾰ effect.

A Super Air Amplifier’s air stream causes a foam ball to be suspended in mid air thanks to the Coandᾰ effect.

Rigid Pipe or Hard Pipe – This is the term we will often use when discussing the compressed air line that can be used to support and supply certain EXAIR products.  Generally we are referring to a Schedule 40 steel pipe, Type L copper line, stainless steel tube, or any form of pressure rated hard pipe that can be used for supplying compressed air.

Plenum – the state or a space in which a gas, usually air, is contained at pressure greater than atmospheric pressure. Many of our products feature a plenum chamber. 

Again, this list is only a sample of the terminology you will hear us use when discussing compressed air applications.  If there are any other air/compressed air/fluid dynamic terms you may be unsure of, please contact us.

Brian Farno
Application Engineer Manager
BrianFarno@EXAIR.com
@EXAIR_BF

Deflated Footballs? What’s the Big Deal, We Talk Air Pressure Everyday

This week we prepare for the professional football championship game, that phrase is trademarked within the Woerner household. For a few years, we have had my friends from college over for guacamole, chicken wings, French fries, and beverages. This year our small family is now three, so we are in for a quiet evening at home. My son will most likely be asleep at kick off, but my wife and I might stay awake for the end of the first quarter. Even with the small amount of people that we will watch the game, I will still make a small spread for our family, because tradition. Tradition says, it’s Super Bowl Week – we buy avocados early in the week so they have time to ripen.

In the build up to the big game, it seems like we always get a very silly story that the media grabs a hold of and just will not let go.  I want to join them. Have you heard about the fact that the footballs that the one of teams used on offense might not have been inflated to the correct pressure. I don’t know that the fotballs were under inflated on purpose, but I also think that LaDainian Tomlinson might have been on to something, when he said “The Patriots live by the saying if you ain’t cheating, you ain’t trying.”

That was a long introduction into my blog today about pressure. The NFL Rule Book states,

“The ball shall be made up of an inflated (12 1/2 to 13 1/2 pounds) urethane bladder enclosed in a pebble grained, leather case (natural tan color) without corrugations of any kind. It shall have the form of a prolate spheroid and the size and weight shall be: long axis, 11 to 11 1/4 inches; long circumference, 28 to 28 1/2 inches; short circumference, 21 to 21 1/4 inches; weight, 14 to 15 ounces.”

From an engineering perspective this is ambiguous at best. If I read this with no knowledge of football, I would have no idea how to test whether the ball is inflated. The rule states that the ball should be an inflated urethane bladder. Then in the parenthetical phrase it lists 12 1/2 to 13 1/2 pounds. Last time I checked pounds is a measure of weight. If I received this specifications, I would put the ball on a scale to weigh it. Using some common sense a quarterback isn’t going to be able to throw a 12 pounds ball, like a bullet, 10 yards. Let alone 60 yards for that deep bomb.

If I was writing the rule book, it would read that “the ball shall be inflated to a pressure of 12 1/2 to 13 1/2 pounds per square inch gauge pressure.” With this wording there is a clear standard to be met for football to be worthy for use.

What Is Gauge Pressure?

Gauge pressure is the pressure determined by a gauge or instrument. The term is used to differentiate pressure registered by a gauge from absolute pressure. Absolute pressure is determined by adding gauge pressure to atmospheric (aka barometric) pressure. Barometric pressure can be calculated based on elevation or measured by a barometer.

What is Atmospheric Pressure?

Andrew Gatt

This bottle was sealed at 10,000 ft above sea level then moved to the beach. At the beach the bottle spontaneously crushed by the increased atmospheric pressure

 

Atmospheric pressure is the force per area that the air around us compresses our world. Above is a photo with a simple illustration of atmospheric pressure. At roughly 10,000 feet above sea level, the bottle is sealed trapping the atmospheric pressure inside the bottle. As the bottle drops in elevation, the pressure outside the bottle rises compressing bottle and the air inside.

When do I use Gauge Pressure?

Gauge pressure is used in a majority of industrial applications. For instance, EXAIR’s air nozzle performance is based on 80 Pounds per Square Inch Gauge (PSIG). No matter what elevation the air nozzles are used the flow rate and the force of the nozzle will be the same as long as the gauge at the inlet to the nozzle reads 80 PSIG.

When do I use Atmospheric Pressure?

I seldom use atmospheric pressure by itself. I often use atmospheric pressure in conjunction with gauge pressure. Meteorologists reference atmospheric pressure when referring to low pressure or high pressure weather systems.

When do I use Absolute Pressure?

In one word: calculations. Absolute pressure is equal to gauge pressure plus atmospheric pressure. In a majority of formulas or calculations, absolute pressure is used. Specifically, whenever you are using pressure to multiply, divide, or raise to a power, absolute pressure is used. There may be exceptions, but I would need to be very familiar with the formula, before I would only use gauge pressure to multiply. For instance, if you need to calculate the air usage at of an air nozzle at a different pressure (as seen in this earlier blog), you would use the absolute pressure. The flow through a nozzle is governed by Bernoulli’s principle.

Dave Woerner
Application Engineer
@EXAIR_DW
DaveWoerner@EXAIR.com

 

Photo Courtesy of Andrew Gatt. Creative Commons License

Actual vs. Standard flows

Have you ever noticed that when a flow rate like SCFM, SLPM, or NM3/hr is reported, there is a pressure associated with it? There is a reason for this. The “S” in SCFM and SLPM, is for Standard, and the “N” in NM3/hr is for Normal. It is the amount of air being used at atmospheric pressure and temperature. To further explain it, if you take a segment of air out of a compressed air line and place it next to you at ambient temperature and pressure, it will expand to a larger volume. Think of it like an air-filled balloon floating on top of the water. This would be the “Standard” or “Normal” condition. As you take the balloon into deeper water, the more pressure is applied to the balloon, and the volume decreases. This is because air is compressible. The balloon still has the same amount of air by weight (as the volume decreases, the density increases). If you return back to the surface, the balloon will expand back to the original size.

Pressure

Pressure

Being that the flow rate for nozzles, knives, etc., are rated at a standard or normal condition, why do we require a pressure rating? It should be at the atmospheric pressure and temperature. Well, this is where it gets tricky. Just like the air-filled balloon, the deeper you go (higher pressures), the less volume is in the balloon. So, when we have different pressures, we are trying to find the actual volume of air being used because that is what you are paying for. Also, this is where the term ACFM (lpm or M3/hr) comes into play. The “A” in ACFM is for Actual (the volume of air at the actual pressure and temperature). Pneumatic devices use this type of flow (ACFM), but for the ease of understanding, they convert it to a SCFM, SLPM, or NM^3/hr at a pressure. If we assume ambient temperatures because most of our products are used there, then the correlation between Actual and Standard is Qa = Qs * Pa/(P +Pa) .

Imperial Units                                    SI units

Qa          Actual flow (ACFM)                         Actual flow (M^3/hr)

Qs           Standard flow (SCFM)                    Normal flow (NM^3/hr)

P             Gage Pressure (psig)                      Gage Pressure (barg)

Pa           Absolute Pressure (psia)                Absolute Pressure (bara)

 

The reason for this explanation is because some competitors like to use a lower pressure to rate their products. As an example, two air nozzles are rated for 70 SCFM (119 NM^3/hr). One nozzle is cataloged at 60 psig (4.1 barg) and the other is cataloged at 80 psig (5.5 barg). By comparison, they look like they use the same amount of compressed air, but actually they do not. Under the actual condition (using the formula above), we have the following:

Imperial Units                                                                    SI Units

@60 psig                                                                              @4.1 barg

Qa = 70 SCFM * 14.7 psia/(60 psig + 14.7 psia)     Qa = 119 NM^3/hr * 1 bara/(4.1 barg + 1 bara)

= 13.8 ACFM (actual amount of air used)                 = 23.3 M^3/hr (actual amount of air used)

 

@80 psig                                                                              @5.5barg

Qa = 70 SCFM * 14.7 psia/(80 psig + 14.7 psia)     Qa = 119 NM^3/hr * 1 bara/(5.5 barg + 1 bara)

= 10.9 ACFM (actual amount of air used)                = 18.3 M^3/hr (actual amount of air used)

 

Even though it seems like they use the same amount of compressed air, you are actually using 27% more air with the nozzle reported at 60 psig than the one that was reported at 80 psig. Always remember that if you want to compare air usage, always do it at the same pressure and temperature. If you need help, you can always contact our application engineers here at EXAIR.

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

 

Image courtesy of UpUpa4me. Creative Comment License

Drilled Holes In A Pipe – Stop Violating OSHA Standards!

The photos below show one of the most common OSHA violations we see at EXAIR.  A  1-1/4” pipe with 5mm holes drilled every 1.5”.  Drilled pipe is a common practice in many facilities for two reasons – One, it is quick and two, is it easy.  The problem with this type of setup is the safety concern if the drilled hole is dead-ended against skin.  A pressure above 30 PSI can force compressed air into the bloodstream, creating the risk for an embolism – a condition which can be fatal. EXAIR’s engineered Super Air Nozzles can save the day.

IMG_4666

5mm holes drilled into a 1-1/4″ pipe (Top)

IMG_4668

5mm holes drilled into a 1-1/4″ pipe (Left)

IMG_4667

5mm holes drilled into a 1-1/4″ pipe (Right)

 

All EXAIR products conform to OSHA standard CFR 1910.424(b), a standard that regulates dead-end pressure level maximums for compressed air products.  The designs of all EXAIR products are developed in such a way that if dead-ended against human skin they will never exceed the maximum pressure mandated by OSHA (30 PSI). In the above case, our Pico Super Air Nozzles are the right solution. With its recent nomination of the 1109-PEEK for the Plant Engineering Product of the Year Award in the Compressed Air Category, I got to thinking about the product.  There are the obvious, material-specific benefits such as the chemical resistivity of PEEK plastic, the high temperature range (160°C/320°F), and the friendly, non-marring qualities when in direct contact with other materials. But, there is also another side to the 1109-PEEK nozzle (and every other EXAIR product), and that is the added safety with every installation.

EXAIR can also supply a quick and easy solution to keep you OSHA safe and conserve air at the same time. With EXAIR’s unmatched variety of sizes and material, we have an in STOCK solution for your drilled pipes. With threads sizes ranging from M4 x 0.5 through 1-1/4 NPT on the shelf, we ship orders same day in most cases. That is the quick part of the equation.

The correction for such a condition can be the easy installation of a Super Air Knife, or Super Air Nozzles (below) – This illustrates the easy part of the equation.

IMG_4672

1109-PEEK nozzles installed into 1-1/4″ pipe

IMG_4669

Closer view of 1109-PEEK nozzles

IMG_4670

Close-up of 1109-PEEK nozzles

IMG_4671

1109-PEEK nozzles lookin good… and SAFE!!

The 1109-PEEK nozzles installed above provide the needed safety to this drilled pipe. The same nozzle is also available in 316 stainless steel. If you have an application with a similar need in your facility, contact an EXAIR Application Engineer to discuss technical details and specific recommendations.

Lee Evans
Application Engineer
LeeEvans@EXAIR.com
@EXAIR_LE

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