The Importance Of Properly Sized Compressed Air Supply Lines

EXAIR Corporation manufactures a variety of engineered compressed air products that have been solving myriad applications in industry for almost 37 years now.  In order for them to function properly, though, they have to be supplied with enough compressed air flow, which means the compressed air supply lines have to be adequately sized.

A 20 foot length of 1/4″ pipe can handle a maximum flow capacity of 18 SCFM, so it’s good for a Model 1100 Super Air Nozzle (uses 14 SCFM @80psig) or a Model 110006 6″ Super Air Knife (uses 17.4 SCFM @80psig,) but it’s going to starve anything requiring much more air than those products.  Since compressed air consumption of devices like EXAIR Intelligent Compressed Air Products is directly proportional to inlet pressure, we can use the flow capacity of the pipe, the upstream air pressure, and the known consumption of the EXAIR product to calculate the inlet pressure of a starved product.  This will give us an idea of its performance as well.

Let’s use a 12″ Super Air Knife, with the 20 foot length of 1/4″ pipe as an example.  The ratio formula is:

(P2 ÷ P1) C1 = C2, where:

P2 – absolute pressure we’re solving for*

P1 – absolute pressure for our published compressed air consumption, or C1*

C1 – known value of compressed air consumption at supply pressure P1

C2 – compressed air consumption at supply pressure P2

*gauge pressure plus 14.7psi atmospheric pressure

This is the typical formula we use, since we’re normally solving for compressed air consumption at a certain supply pressure, but, rearranged to solve for inlet pressure assuming the consumption will be the capacity of the supply line in question:

(C2 P1) ÷ C1 = P2

[18 SCFM X (80psig + 14.7psia)] ÷ 34.8 SCFM = 49psia – 14.7psia = 34.3psig inlet pressure to the 12″ Super Air Knife.

From the Super Air Knife performance chart…

This table is found on page 22 of EXAIR Catalog #32.

…we can extrapolate that the performance of a 12″ Super Air Knife, supplied with a 20 foot length of 1/4″ pipe, will perform just under the parameters of one supplied at 40psig:

  • Air velocity less than 7,000 fpm, as compared to 11,800 fpm*
  • Force @6″ from target of 13.2oz total, instead of 30oz*
  • *Performance values for a 12″ length supplied with an adequately sized supply line, allowing for 80psig at the inlet to the Air Knife.

Qualitatively speaking, if you hold your hand in front of an adequately supplied Super Air Knife, it’ll feel an awful lot like sticking your hand out the window of a moving car at 50 miles an hour.  If it’s being supplied with the 20 foot length of 1/4″ pipe, though, it’s going to feel more like a desk fan on high speed.

The type of supply line is important too.  A 1/4″ pipe has an ID of about 3/8″ (0.363″, to be exact) but a 1/4″ hose has an ID of only…you guessed it…1/4″.  Let’s say you have 20 feet of 1/4″ hose instead, which will handle only 7 SCFM of compressed air flow capacity:

[7 SCFM X (80psig + 14.7psia)] ÷ 34.8 SCFM = 19psia – 14.7psia = 4.3psig inlet pressure to the 12″ Super Air Knife.

Our Super Air Knife performance chart doesn’t go that low, but, qualitatively, that’s going to generate a light breeze coming out of the Super Air Knife.  This is why, for good performance, it’s important to follow the recommendations in the Installation Guide:

This table comes directly from the Installation & Operation Instructions for the Super Air Knife.
All Installation Guides for EXAIR Intelligent Compressed Air Products contain recommended air supply line sizes for this very reason.  If you have any questions, though, about proper compressed air supply, give me a call.

Russ Bowman
Application Engineer
EXAIR Corporation
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Process Improvement, ROI and Safety from One Air Nozzle

Process improvement projects can be detailed, complex, expensive, and take a long time to prove their worth.  Today, I want to tell you about one that WAS NOT ANYTHING like that.

A metal stamping company used compressed air to blow their products from their dies.  They did what many do – they ran some copper tubing, and aimed it at the platen so it would properly eject the parts as they were stamped.  They KNEW it was loud, and they suspected it was inefficient as well.

After discussing the setup and seeing a picture of it (the one on the left, below,) I recommended installing a few engineered Super Air Nozzles to lower the noise levels considerably.  Boy, was I wrong.  About “a few” nozzles, that is…turns out, they only needed one Model 1122-9212 2″ Flat Super Air Nozzle with 12″ Stay Set Hose.  The copper tubes come from a manifold that already had 1/4 NPT ports – installation took a matter of minutes.  Nothing detailed, complex, or expensive about it:

This loud & inefficient copper tubing blowoff was just a compression fitting (and a Model 1122 2″ Flat Super Air Nozzle) away from being quiet and efficient.

It didn’t take much longer than that to prove its worth either: as soon as they noticed how much the noise level went down on THIS press, they ordered them for the other eighteen presses in their facility as well.

The 1/4″ copper tubes blew continuously from a pressure regulator set @60psig…the three of them theoretically consumed a total of ~80 SCFM.  The Model 1122, at 60psig supply, consumes only 17.2 SCFM.  Simple return on investment was as follows:

  • 80 SCFM was costing them $48.00 a week
    • 80 SCFM X 60 min/hr X 8 hr/day X 5 days/week X $0.25/1,000 CFM = $48.00
  • 17.2 SCFM, using the same formula, only costs $10.32 a week (I’ll let you do the math; it’s good practice.)
  • They saved $37.68 a week.  The Model 1122-9212 costs $116.00 (2020 pricing) – that means that each of them paid for themselves in just a hair over three weeks.
  • $37.68 x 50 work weeks per year = $1884.00 saved annually per nozzle
  • $1884 x 18 (the number of presses) = $33,912 saved annually 

Considering they also didn’t have to listen to those very loud open ended copper tube blowoffs, I think you’ll have to agree it made for a very good investment.  They did. The new nozzle runs at 77 decibels, a comfortable level and well below the OSHA standard [29 CFR – 1910.95(a)] for allowable noise exposure.

If you’d like to find out how EXAIR Intelligent Compressed Air Products can save you money on compressed air – and save everyone’s hearing – give me a call.

Russ Bowman
Application Engineer
EXAIR Corporation
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Reduce Sound Levels In Less Than A Minute

Okay, I will admit, the title may be a tad bit leading.  The fact is, it can be done.  I speak to customers almost daily who are struggling with the noise levels produced from open pipe blowoffs.  With Noise Induced Hearing Loss (NIHL) a significant problem among manufacturing workers, reducing the noise form compressed air can be a simple solution and contribute toward reducing overall noise exposure levels. Many of these calls and emails revolve around reducing these exact noise levels, sometimes the open pipes have existing threads on them to install the solution immediately.

To reduce these noise levels, we need to simply reduce the amount of energy that is being expelled through the pipe. How do we do this you might ask?  The use of an air nozzle will reduce the energy being dispersed from an open pipe.  This will result in lower air consumption as well as lower sound levels while actually increasing velocity as the pipe will maintain higher operating pressures. Be cautious about the air nozzle you choose, however, they are not all created equal. EXAIR’s engineered air nozzles are among the quietest and most efficient air nozzles available.

Family of Nozzles

What size pipes can we fit nozzles to?  That’s a great question.  We have nozzles that range from a 4mm straight thread all the way up to 1-1/4″ NPT thread.  This also includes nearly any size in between especially the standard compressed air piping sizes.  For instance, a 1/4″ Sched. 40 pipe that has 1/4″ MNPT threads on it can easily produce over a 100 dBA noise level from 3 feet away.  This can easily be reduced to below 80 dBA from 3′ away by utilizing one of our model 1100 Super Air Nozzles.  All it takes is a deep well socket and ratchet with some thread sealant.

This doesn’t just lower the sound level though, it reduces the amount of compressed air expelled through that open pipe by creating a restriction on the exit point.  This permits the compressed air to reach a higher line pressure causing a higher exit velocity and due to the engineering within the nozzle, this will also eliminate dangerous dead-end pressure and complies with OSHA standard 29 CFR 1910.242(b).

Easy Install

All in all, a 30-second install can make an operator’s work station considerably quieter and potentially remove the need for hearing protection.  If you would like to discuss how to lower noise levels in your facility, contact us.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF

Air Savings Calculator

I received an email from an engineer that was looking at our Super Air Nozzles.  They currently were using four blow-off lines that were made from 6mm ID copper tubes. The system was designed to blow out holes after machining.  The engineer was in charge of the task of optimizing 25 machining stations similar to this one.  He was familiar with EXAIR products from his previous employment, and he recognized the waste of compressed air by using open pipe.  He purchased four Nano Super Air Nozzle, model 1110SS, for a trial.  He was impressed with the performance, the low sound level, and the engineered design in safety.  But, for upper management in his company, he had to show a cost savings in order to change all the stations in the facility.  He asked me to help him in calculating the compressed air savings.

nano nozzle

He gave me some additional details about their application.  He was using the compressed air about 30% of the time throughout an 8 hour day at a pressure of 80 PISG.  He wanted to present the savings per day, week, and year as well as the payback period in his evaluation.  I have performed many of these calculations for other customers and was happy to help.  It is sometimes easier to speak in terms of savings, as everyone can relate to money, especially management.

Knowns:

Flow: 1110SS Nano Super Air Nozzle – 8.3 SCFM at 80 PSIG

Flow:  6mm ID copper tube – 42 SCFM at 80 PSIG

This is where the COST SAVINGS CALCULATOR on our website shines!

The Calculator tells us you will see a ROI (Return on investment) is less than 5 days! And will save you $3,033.00 over a full year on compressed air generation cost alone!

Don’t be fooled by the initial cost of a tube, pipe, drilled holes, or a substandard nozzle.  You can see by the facts above, if you use any additional compressed air in your blow-off application, it will cost you a lot of money in the long run.  If you need any help in calculating how much money EXAIR products can save you, you can use our Air Savings Calculator from our website, or you contact an Application Engineer at EXAIR.  We will be happy to help you.

Jordan Shouse
Application Engineer

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