Finding and Fixing Leaks in Your Compressed Air System

I had to find and fix some leaks this week – in my yard. See, my underground storm sewer pipe, that carries my basement sump pump discharge and my house’s gutter drains to the street, was leaking.

The evidence was clear…swampy puddles were developing in my neighbor’s yard.

The location was clear…several patches of grass in MY yard were WAY more green and vibrant than the rest.

The cause was NOT clear…until I dug up those patches of the best looking grass my lawn has ever seen. Turns out, my maple tree’s (the showpiece of my front yard) root system found a way to penetrate one of the couplings in the sewer pipe, where it prospered into this:

That’s about 8ft worth of root growth that was clogging my drain pipe, and causing leaks upstream. My maple tree is not shown in the picture because my maple tree is a real jerk.

Two days worth of digging up and reinstalling pipe later, and all is well.  I mean, except for filling the trench, sowing some new grass seed, watching the birds eat it, sowing some more, etc.  Ah, the joys of home ownership…

I tell you all this, dear reader, so you know that I. Don’t. Like. Leaks…whether they be in my storm sewer pipe or in your compressed air system…which brings me to the (real) subject of my blog today.

Unlike the visual indications of my yard leak, compressed air system leaks don’t really draw much attention to themselves.  Unless they grow quite large, they’re typically invisible and very quiet…much too quiet to be heard in a typical industrial environment, anyway.  Good news is, they’re not all that hard to find.

One way is to use a soap-and-water solution.  You just need a spray bottle, some dish soap, and water.  Spray it on the piping joints, and all but the smallest, most minute, of leaks will create soap bubbles…instant indication of air leakage.  This method is inexpensive and simple, but it does tend to leave little puddles all over.  Plus, if your header runs along the ceiling, you’re going to have to get up there to do it.  And unless you can easily maneuver all the way around the pipe, you can miss a leak on the other side of the joint. If you have a small and relatively simple compressed air system, and all your piping is accessible though, this method is tried and true.

For many industrial compressed air systems, though, the limitations of the soap bubble method make it impractical.  But I’ve got more good news: those silent (to us) air leaks are making a real racket, ultrasonically speaking.  And we’ve got something for that:

EXAIR Model 9061 Ultrasonic Leak Detector discovers and pinpoints leaks, quickly and easily.

See, when a pressurized gas finds its way through the narrow (and usually torturous) path out of a slightly loosened fitting, worn packing on a valve, etc., it creates sound waves.  Some of those ARE in audible frequencies, but they’re often so low as to be drowned out by everything else that’s happening in a typical industrial environment.  Those leaks, however, also create sound waves in ultrasonic frequencies…and EXAIR’s Ultrasonic Leak Detector takes advantage of that ultrasonic racket to show you where those leaks are, as well as give you a qualitative indication of their magnitude.  Here’s how it works:

Find leaks and fix them.  This is Step #2 of our Six Steps To Optimizing Your Compressed Air System.  If you’d like to find out more, give me a call.

Russ Bowman
Application Engineer
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Discharge of Air Through an Orifice

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.

DischargeThroughAnOrifice

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-EquationWhere:
Equation Variables

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.

Brian Bergmann
Application Engineer

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Estimating the Cost of Compressed Air Systems Leaks

Leaks in a compressed air system can waste thousands of dollars of electricity per year. In fact, in many plants, the leakage can account for up to 30% of the total operational cost of the compressor. Some of the most common areas where you might find a leak would be at connection joints like valves, unions, couplings, fittings, etc. This not only wastes energy but it can also cause the compressed air system to lose pressure which reduces the end use product’s performance, like an air operated actuator being unable to close a valve, for instance.

One way to estimate how much leakage a system has is to turn off all of the point-of-use devices / pneumatic tools, then start the compressor and record the average time it takes for the compressor to cycle on and off. The total percentage of leakage can be calculated as follows:

Percentage = [(T x 100) / (T + t)]

T = on time in minutes
t = off time in minutes

The percentage of compressor capacity that is lost should be under 10% for a system that is properly maintained.

Another method to calculate the amount of leakage in a system is by using a downstream pressure gauge from a receiver tank. You would need to know the total volume in the system at this point though to accurately estimate the leakage. As the compressor starts to cycle on,  you want to allow the system to reach the nominal operating pressure for the process and record the length of time it takes for the pressure to drop to a lower level. As stated above, any leakage more than 10% shows that improvements could be made in the system.

Formula:

(V x (P1 – P2) / T x 14.7) x 1.25

V= Volumetric Flow (CFM)
P1 = Operating Pressure (PSIG)
P2 =  Lower Pressure (PSIG)
T = Time (minutes)
14.7 = Atmospheric Pressure
1.25 = correction factor to figure the amount of leakage as the pressure drops in the system

Now that we’ve covered how to estimate the amount of leakage there might be in a system, we can now look at the cost of a leak. For this example, we will consider a leak point to be the equivalent to a 1/16″ diameter hole.

A 1/16″ diameter hole is going to flow close to 3.8 SCFM @ 80 PSIG supply pressure. An industrial sized air compressor uses about 1 horsepower of energy to make roughly 4 SCFM of compressed air. Many plants know their actual energy costs but if not, a reasonable average to use is $0.25/1,000 SCF generated.

Calculation :

3.8 SCFM (consumed) x 60 minutes x $ 0.25 divided by 1,000 SCF

= $ 0.06 per hour
= $ 0.48 per 8 hour work shift
= $ 2.40 per 5-day work week
= $ 124.80 per year (based on 52 weeks)

As you can see, that’s a lot of money and energy being lost to just one small leak. More than likely, this wouldn’t be the only leak in the system so it wouldn’t take long for the cost to quickly add up for several leaks of this size.

If you’d like to discuss how EXAIR products can help identify and locate costly leaks in your compressed air system, please contact one of our application engineers at 800-903-9247.

Justin Nicholl
Application Engineer
justinnicholl@exair.com
@EXAIR_JN

 

 

 

 

 

Step 2 of Optimizing Your Compressed Air System, Find & Fix Leaks

Over the past handful of blog posts I have blogged about topics like understanding the demand on your compressor, creating a system pressure profile,  and the effectiveness of filtering your compressed air.  These are all critical steps in ensuring your compressed air system is optimized for maximum efficiency.   These can also all fall into place with our Six Steps To Compressed Air Optimization.

EXAIR Six Steps To Optimizing Your Compressed Air System
EXAIR Six Steps To Optimizing Your Compressed Air System

Another factor in the six steps is identifying and addressing leaks within your system.   Finding leaks in your compressed air system can be done several ways, one of the oldest methods is to use a soap and water mixture to spray on every joint and see if there is a leak that causes bubbles.   The next method would be to use ball valves and pressure gauges to test each run of pipe to ensure they are holding their pressure over a period of time, similar to a leak down test.  The final method, and by far the easiest, would be to utilize our Ultrasonic Leak Detector.

This can be used to sense leaks in compressed air systems up to 20′ away and can also pin point a leak by closely monitoring each joint.  Neal Raker made a great video on how to use the Ultrasonic Leak Detector a while back and it is shown below.

If you have any questions on how to find leaks or how to optimize your compressed air system, give us a call.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF

Being Prepared

My sons went skiing with their Boy Scout troop this past weekend. It was the first time my youngest, who turns 12 next month, had been skiing, and he had a blast on the beginner’s slope and the tubing lanes. His 14 year old brother, however, is a grizzled veteran, having hit the slopes three whole times over the past three years. He’s quite athletic, though – this stuff just comes natural to him – so he and his friends spent most of their time on the “difficult” (marked by a blue square on the map) and “advanced intermediate” (blue square with a black diamond) courses. I don’t know much about skiing, but I do know that any slope represented with a black diamond is one that I do NOT belong on.

I mentioned his athleticism – right now, he’s in the middle of basketball season, his baseball team’s prospective pitchers and catchers are working out, and right after winter break, his football team began off-season weight training after school, three days a week. In the midst of all this, he still managed to find some muscles to get sore while skiing. Not as many as some of the other Scouts, though, considering the comments I heard at last night’s Troop meeting. They are all, however, looking forward to next year’s trip.

I tell you this, dear reader, because:
1. It reminded me of a conversation I once had with a customer, and,
2. It’s been a while since I wrote anything about Boy Scouts.

Now that #2 is out of my system, the customer wanted to discuss our Ultrasonic Leak Detector. He had recently purchased a Super Air Knife, and its performance made him think of where else he might be able to make improvements in his compressed air system. Since he had flow meters in place already (see The Six Steps To Optimizing Your Compressed Air System,) he turned to leak detection & repair. In other words, he wanted to find out where his system, much like my son’s hip & lateral abdominal muscles, was vulnerable.  Now that he’s finding out if he has any leaks to fix, he can move on to the next step of upgrading their operations with engineered compressed air products.

ultrasonic_2

And now that my son knows, very specifically and unforgettably, which muscle groups he needs to work on before the next ski trip, I hope he’ll consider some advance preparation next time. Even more than that, I hope that I’ll actually be able to join them then.

Russ Bowman
Application Engineer
russbowman@exair.com
Twitter: @EXAIR_RB

Monitoring Is Apparently The New Thing To Do

Over the past month, I have been loosely watching the events revolving around a former government contractor, Edward Snowden.   The contractor leaked classified information about how the NSA monitors the US citizens.   This has of course brought on a large amount of news coverage and lots of questions from the US citizens to the government.  Others have been able to turn it into a laughing matter like Jimmy Kimmel did on his show.   Below is the commercial Jimmy did for the NSA on his show.

So with all the talk about how every little thing you do is monitored, and I am probably going to end up on several lists for keywords in this blog, why not begin your own monitoring campaign.

dataloggerPRce_559widesrd

EXAIR offers a full line of monitoring devices for your compressed air system, after all it’s the first step in the 6 Steps To Compressed Air Optimization.  The best part of our offering is that you can not only use the EXAIR Digital Flowmeter to monitor your compressed air system, when combined with the Summing remote display and/or the USB Data Logger, you can also collect the data from the meter.

The complete setup will allow you to easily see, and calculate, your cost savings before and after you implement an Intelligent Compressed Air product.

If you have any questions on how EXAIR can help you monitor your compressed air system, give us a call, chat, fax or e-mail.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF