Month: September 2013

Intelligent Compressed Air® Solutions For Industry

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My son was complaining about his unusually high water bill. I advised him to look for leaks around the house. Checking for leaks and how to check for them is something that I have been assisting customers with for the last 19 years. Water, compressed air, no difference. A leak is a leak. It did not take me long to find his problem. He had left the water on to a garden hose. Lying in the hot sun, it developed a bulge in the hose that eventually burst.

Leak Detector

With compressed air systems, when pressure loss becomes a problem, the first thing auditors look for are leaks. EXAIR has a handheld ultrasonic leak detector that can find leaks that you may not be able to hear. This instrument detects inaudible sounds emitted from the smallest of leaks.

Having found and fixed all the leaks, the job is not done. Over time, inefficient compressed air devices are added to the system. Air blow off probably is the leading offender and open copper pipe is usually the culprit.

open-pipe-blow-off

Open pipe not only wastes compress air but it is not compliant to the OSHA dead ended pressure and can also violate sound level exposure requirements. The solution is to install EXAIR engineered nozzles. They can cut operating costs since they use only a fraction of the compressed air of typical blow-offs and comply with the OSHA sound and dead ended pressure directives.

nozzle array

EXAIR has a full range of sizes of engineered air nozzles ranging from the size as small as a grain of rice up to 1 1/4″ NPT. With so many selections you may not know which one to decide on and that is where our application engineers come in. Feel welcomed to give them a call at 1-800-903-9247. They truly would appreciate the opportunity to assist you.

Joe Panfalone
Application Engineer
Phone (513) 671-3322
Fax (513) 671-3363
Web: http://www.exair.com
Twitter: http://www.twitter.com/exair_jp
Facebook: http://www.facebook.com/exair

Vacuum Generators: Porous Vs. Non-Porous

Published on by Dave WoernerLeave a comment

I had customer call this week who was using an E-Vac model 800008H, an 8 SCFM Porous Vacuum Generator, to pull a vacuum on four vacuum cups.  He was trying to lift a part with the four vacuum cups placed on a clean metal portion of the part.  Unfortunately he was having a little trouble.  He had to lift the product very slowly because the part could easily be dislodged, if the part was bumped or came to an abrupt stop.

In-LineE-VacFamily
EXAIR’s family of In-Line E-Vac vacuum generators

The problem is a relatively simple one.  The customer choose a porous vacuum generator when he would be better served with a non-porous unit.  The vacuum cups are attaching to a non-porous surface, sheet metal, in a relatively clean environment.  The difference between porous and non-porous units is that  porous units has more vacuum flow available at a low vacuum level, where the non-porous vacuum generators have a higher level of vacuum, but less vacuum flow.  Because of the high vacuum flow, a porous unit is much better for lifting porous materials like cardboard, some particle boards, and fabrics.  The higher vacuum flow of porous vacuum generators helps maintain the vacuum when pulling upon materials which let a constant flow of air through. In the customer’s case, he was lifting a clean sheet of metal, a non-porous material, and needed a higher vacuum level as opposed to a higher vacuum flow. A higher vacuum level [more inches of mercury (Hg) of vacuum] would pull harder upon the metal and hold it tighter.

Let’s look at the customer’s example more closely.  An EXAIR model 800008, porous E Vac, will generate a maximum of 21 inches of mercury (“Hg).  A model 810008, non-porous E Vac, will generate 27  inches of mercury (“Hg).  Let say he was using a 900758 3 1/4” diameter round vacuum cup. If you look at the Vacuum Lift Chart, you see that the 900758 can lift 42.8 lbs. at 21 “HG, but it can lift 55.0 pounds at 27 “HG of mercury.  So in this application the customer can increase their lifting capacity by 28.5% by switching from a non-porous vacuum generator to a porous vacuum generator.

Dave Woerner
Application Engineer
davewoerner@exair.com
@EXAIR_DW

Advanced Management of Compressed Air – Storage and Capacitance

Published on by Lee Evans2 Comments

Receiver Tank Drawing

Last week I attended the Advanced Management of Compressed Air Systems seminar put on by the Compressed Air Challenge.  For those unfamiliar with the Compressed Air Challenge, it’s an organization focused on delivering reliable and sustainable compressed air that has maximized efficiency.  Many of the industry’s best practices are preached, if not mandated, and the ultimate goal is to reduce compressed air use as much as possible.  This fits in line with EXAIR products, their design for maximum efficiency, and the recurring ability of our customers to reduce their compressed air use by using our products.

The “advanced” seminar dives into compressed air system profiles, explores the math and theory behind system design, explains the various types of system controls, and shows how to balance compressed air supply and demand.  These things are great not only on their inherent value, but also because when Brian Farno, Russ Bowman, and I attended the Fundamentals of Compressed Air Systems seminar, we kept raising our hands asking questions that were “too advanced”.  The material presented here answered many of those questions, and sparked a few new ones.

One of the questions that came to me during the training had to do with the capacitance of a compressed air system.  When storing the energy of a compressed air system in a receiver tank, there has to be a pressure gradient in order for there to be energy storage.  If a receiver tank has the same inlet and outlet pressure, it is merely part of the system plumbing and provides no benefit to the system when demand peaks.  So I thought to myself, “if a pressure drop is needed across a receiver tank to achieve system capacitance, and the capacitance of the system is related to the value of that differential, a system could theoretically be supplied enough compressed air volume with the right pressure specs”.

So, I looked to the formula used for sizing a receiver tank.

V = (T x (C – R) x Pa)/P1-P2

Where:

V = Receiver volume in cubic feet

T = Time of the event in minutes (amount of time for which the receiver tank must be able to provide compressed air at the needed rate)

C = Intermittent demand amount (how much flow or “Q”) in CFM

R = Flow into tank during event (through needle valve, spare air in system, etc.) in CFM

Pa = Absolute atmospheric pressure (14.7 PSIA)

P1 = Initial receiver tank pressure (in PSI)

P2 = Final receiver tank pressure (in PSI)

Ok, nothing new there.  First grade stuff.  Plugging in some theoretical values we could say:

T = 1 minute

C = 50 cubic feet per minute

R = 0 cubic feet per minute.  In this example we’ll assume there is no residual compressed air flow and that the receiver tank must deliver all the airflow for the duration of the event.

Pa = 14.7

P1 = 100 PSIG

P2 = 90 PSIG

Using these values, the volume calculates to be 73.5 cubic feet.  But, most receiver tanks are sized in gallons so we can multiply by 7.48 to get the figure in gallons.  (7.48 gallons = 1 cubic foot)  This yields an approximate value of 550 gallons.  In plain terms, for the application above, we would need a 550 gallon receiver tank with an inlet pressure of 100 PSIG and an outlet pressure of 90 PSIG to provide compressed airflow over the needed (1) minute duration.

That’s a big tank.

Now, back to my thought on pressure differentials – if we increase the ΔP, we can decrease the size of the receiver tank.  Let’s say the inlet pressure to the receiver tank can be as high as 130 PSIG (a wet tank, in line before any filters or dryers).  This will quadruple the pressure differential and reduce the size of the tank by 75% to 138 gallons.  Great!

Well, great for a new system, but what about one already in place?  What if the application needs 50 CFM of compressed air flow for 1 minute, and the shop already has a 175 gallon tank.  We can work the equation in reverse to determine the necessary pressure differential that will ensure the system has enough capacitance to sustain the event (approximately 32 PSI).  It’s good to know the math.

As a whole, the seminar was a great success and the presenters proved why they’re experts in the field of compressed air.  We’re not too shabby here at EXAIR either.  If you have an application need, give us a call.

Lee Evans
Application Engineer
LeeEvans@EXAIR.com
@EXAIR_LE

What The 30 Day Unconditional Guarantee Can Do For You. And Us.

Published on by Russ BowmanLeave a comment

If you’re reading this, then we must have one thing in common: we’re regular visitors to the EXAIR Blog. I work with these guys, so, odds are, I’ve heard it before I read it (and I want you to know that’s not always a blessing), but I still read them…mainly for the pictures.

This has nothing to do with my blog, but it's just awesome.
This has nothing to do with my blog, but it’s just awesome.

The other day, Brian Farno wrote a great piece on how to use our 30 Day Unconditional Guarantee to “prove out” an application before ordering a custom made (and non-returnable) product. Some folks are hesitant to do this, because they feel bad about taking advantage of us – “gaming the system,” I’ve heard it called. Don’t. It’s still better for both of us than sticking you with something that doesn’t give the desired results, and you can’t return.

I helped a customer a while back with a static elimination application – they were interested in a 102” long Super Ion Air Knife…this was an ideal case where a 96” long unit could be used to test performance. This one turned out even better than anyone expected: they actually got the results they were looking for from the 96” Super Ion Air Knife, so we were all pleased.

Another benefit of the Guarantee is, we get to find out where things DON’T work. This can be just about as valuable as knowing where they DO work. I’ve gained many a potential customer’s trust by being up-front with them, and, if I know what DOES work, I’ll be happy to tell you where you might be able to get it. We all will…we want to be your first call for your compressed air application needs. Try us.

Russ Bowman
Application Engineer
EXAIR Corporation
(513)671-3322 local
(800)923-9247 toll free
(513)671-3363 fax
Web: http://www.exair.com
Blog: http://blog.exair.com/
Twitter: twitter.com/exair_rb
Facebook: http://www.facebook.com/exair