How to Calculate and Avoid Compressed Air Pressure Drop in Systems

EXAIR has been manufacturing Intelligent Compressed Air Products since 1983.  They are engineered with the highest of quality, efficiency, safety, and effectiveness in mind.  Since compressed air is the source for operation, the limitations can be defined by its supply.  With EXAIR products and pneumatic equipment, you will need a way to transfer the compressed air from the air compressor.  There are three main ways; pipes, hoses and tubes.  In this blog, I will compare the difference between compressed air hoses and compressed air tubes.

The basic difference between a compressed air hose and a compressed air tube is the way the diameter is defined.    A hose is measured by the inner diameter while a tube is measured by the outer diameter.  As an example, a 3/8” compressed air hose has an inner diameter of 3/8”.  While a 3/8” compressed air tube has an outer diameter that measures 3/8”.  Thus, for the same dimensional reference, the inner diameter for the tube will be smaller than the hose.

Why do I bring this up?  Pressure drop…  Pressure Drop is a waste of energy, and it reduces the ability of your compressed air system to do work.  To reduce waste, we need to reduce pressure drop.  If we look at the equation for pressure drop, DP, we can find the factors that play an important role.  Equation 1 shows a reference equation for pressure drop.

Equation 1:

DP = Sx * f * Q1.85 * L / (ID5 * P)

DP – Pressure Drop

Sx – Scalar value

f – friction factor

Q – Flow at standard conditions

L – Length of pipe

ID – Inside Diameter

P – Absolute Pressure

 

From Equation 1, differential pressure is controlled by the friction of the wall surface, the flow of compressed air, the length of the pipe, the diameter of the pipe, and the inlet pressure.  As you can see, the pressure drop, DP, is inversely affected by the inner diameter to the fifth power.  So, if the inner diameter of the pipe is twice as small, the pressure drop will increase by 25, or 32 times.

Let’s revisit the 3/8” hose and 3/8” tube.  The 3/8” hose has an inner diameter of 0.375”, and the 3/8” tube has an inner diameter of 0.25”.  In keeping the same variables except for the diameter, we can make a pressure drop comparison.  In Equation 2, I will use DPt and DPh for the pressure drop within the tube and hose respectively.

Equation 2:

DPt / DPh = (Dh)5 / (Dt)5

DPt – Pressure drop of tube

DPh – Pressure Drop of hose

Dh – Inner Diameter of hose

Dt – Inner Diameter of tube

Thus, DPt / DPh = (0.375”)5 / (0.25”)5 = 7.6

As you can see, by using a 3/8” tube in the process instead of the 3/8” hose, the pressure drop will be 7.6 times higher.

Diameters: 3/8″ Pipe vs. 3/8″ tube

At EXAIR, we want to make sure that our customers are able to get the most from our products.  To do this, we need to properly size the compressed air lines.  Within our installation sheets for our Super Air Knives, we recommend the infeed pipe sizes for each air knife at different lengths.

There is also an excerpt about replacing schedule 40 pipe with a compressed air hose.  We state; “If compressed air hose is used, always go one size larger than the recommended pipe size due to the smaller I.D. of hose”.  Here is the reason.  The 1/4” NPT Schedule 40 pipe has an inner diameter of 0.364” (9.2mm).  Since the 3/8” compressed air hose has an inner diameter of 0.375” (9.5mm), the diameter will not create any additional pressure drop.  Some industrial facilities like to use compressed air tubing instead of hoses.  This is fine as long as the inner diameters match appropriately with the recommended pipe in the installation sheets.  Then you can reduce any waste from pressure drop and get the most from the EXAIR products.

With the diameter being such a significant role in creating pressure drop, it is very important to understand the type of connections to your pneumatic devices; i.e. hoses, pipes, or tubes.  In most cases, this is the reason for pneumatic products to underperform, as well as wasting energy within your compressed air system.  If you would like to discuss further the ways to save energy and reduce pressure drop, an Application Engineer at EXAIR will be happy to assist you.

 

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

Back Blow Nozzles Clean Inside Metal Tubes

A manufacturing plant EXAIR worked with made cast aluminum tubes for the automotive industry.  After the parts were cast, a machining operation would clean the ends.  This left coolant and metal shavings inside the tube.  Before going to assembly, they had to clean the part.  They created a two-tube fixture (reference picture above) to fit the 25mm tubes in place.

Two home-made nozzles were used to fit inside the tubes to blow compressed air.  The nozzles were attached to the ends of two 17mm pipes which supplied the compressed air.  A cylinder was used to push the nozzles from the top of the aluminum tube to the bottom then back up again.  The liquid emulsion and debris would be pushed downward into a collection drum.  When they started operating their system, the inside of the tubes still had contamination inside.  They wanted to improve their process, so they looked for an expert in nozzle designs, EXAIR.

Back Blow Air Nozzle Family

EXAIR designed and manufactures a nozzle for just this type of operation, the Back Blow Air Nozzles.  We offer three different sizes to fit inside a wide variety of diameters from ¼” (6.3mm) to 16” (406mm).  They are designed to clean tubing, pipes, hoses, and channels.  The 360o rear airflow pattern can “wipe” the entire internal surface from coolant, chips, and debris.  For the application above, I recommended the model 1006SS Back Blow Air Nozzle.  This 316SS robust design would fit inside the tubes above.  The range for this Back Blow Air Nozzle is from 7/8” (22mm) to 4” (102mm) diameters.  The customer did have to modify the function of the equipment by placing the cylinder and the rods under the aluminum tubes.  The reverse airflow would still push the contamination into the collection drum that was placed underneath the tubes.

After installing the model 1006SS onto the rods, the cleaning operation became more efficient.  Not only was the entire internal diameter getting clean, they were able to turn off the compressed air until they reached the top of the tube.  With the model 1006SS, they only needed one pass to clean.  This cut the air consumption in half, saving them much money by using less compressed air.  In addition, they were able to speed up their operation by 20%.  Cleaner tubes, less time, cost savings; they were happy that they contacted EXAIR for our expertise.

Reverse Air Flow

If you need to clean the inside of tubes, hoses, pipes, etc., EXAIR has the perfect nozzle for you, the Back Blow Air Nozzles.  EXAIR can also offer these nozzles on our VariBlast, Soft Grip and Heavy Duty Air Guns for manual operations.  They come with Chip Shields and extensions that can reach as far as 72” (1829mm).  Or like the customer above, automate the system to get a great non-contact cleaning.

If you require any more details, you can contact an Application Engineer at EXAIR.  We will be happy to help.

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

Custom Solutions For Conveying Dry Material

The ideal solution for conveying large volumes of material over long distances.

EXAIR’s Line Vac compressed air operated conveyors have no moving parts or motors to wear out, providing a maintenance free way to move dry material from one location to another. We offer several different types and sizes of Line Vacs like our Standard Line Vacs, available from 3/8″ up to 5″  or our Threaded Line Vacs, with NPT threaded connections up to 3″. The Heavy Duty Line Vac are constructed of Hardened Alloy for superior abrasion resistance, available in sizes from 3/4” to 3”, smooth and threaded connections or the Light Duty Line Vac commonly used for smaller volume, shorter distance processes, with sizes from 3/4″ to 6”. We even offer Sanitary Flange Line Vacs from 1-1/2″ up to 3″ for processes requiring frequent cleaning. All of these products are in stock, ready to ship from our factory here in Cincinnati, Ohio.

For over 34 years, EXAIR has been manufacturing Intelligent Compressed Air Products and we understand that there may be “special” cases where a stock product isn’t going to fit a specific need or requirement. What sets us apart from our competition is that we are able, with a little help from the customer, to engineer and manufacture custom made products, like the Line Vac Conveyors, to fit the specific demand of a unique application.

A few examples are shown below:

Flanged design, easy to install


This special 3/4″ Stainless Steel flanged Line Vac is being used to remove acidic vapors after a silicon wafer etching process. The flanged design allowed the user to direct mount to the machine, eliminating the need for other expensive modifications.

 

 

 

Chemical resistant construction for washdown areas

 

 

A customer was needing a special Line Vac for a chloride wash area due to the aggressive chemicals. We were able to make a custom 1-1/2″ Line Vac in PVDF construction for corrosion resistance and QF flanges for easy maintenance and cleaning.

 

 

 

Custom funnel design for small, granulated material like sugar or salt

 

This special funnel shaped Line Vac is being used in a a small packet filling operation. The unique design assured for a clog free process by keeping the granulated material moving through the tube.

 

 

 

 

 

Miniature size for confined workspaces

 

A company was needing a miniature version of a Line Vac to remove microscopic debris in an integrated circuit chip making process. The barb fittings allowed for easy installation into the small work place.

 

 

 

 

 

These are just a few examples of how we are able to meet the demands of a wide variety of extraordinary processes. Whether you are looking to move “common” materials like plastic pellets or maybe something “off the wall”, chances are we have the resources to provide an engineered solution to fit your need. Our application engineers are standing by, so give us a call and let us put our expertise to work for you!

Justin Nicholl
Application Engineer
justinnicholl@exair.com
@EXAIR_JN

 

 

Line Vac – Air Operated Conveyors

Convey parts, materials, and waste – with no moving parts!

The Line Vac is a fast, low cost way to convey pellets, scrap trim, textiles, bulk solids, food products, chips, and much more.  Simply connect to a standard hose, tube, or pipe and a powerful in-line conveyor is created.

Available in (4) materials – aluminum, 303 and 316 stainless steels, and a special hardened alloy, and (3) end connection types – NPT threaded, smooth bore, and the new sanitary flanged. Sizes range from 3/8″ up to a 6″. It is certain that an available Line Vac option will meet your process criteria.

For lighter materials and short conveyance distances, the Light Duty model is ideal, and for the most abrasive and heaviest materials over longer distances, the Heavy Duty style is available.

The Line Vacs offer many safety benefits, including eliminating the dangers of lifting heavy sacks and climbing ladders to fill hoppers, and with the 316 stainless steel sanitary flanged Line Vacs, food materials are kept enclosed and and separated and provides ease of cleaning.

Check out the video by clicking the photo below

Capture

The Line Vac works by having a small amount of compressed air injected through directed nozzles to produce a vacuum on one end and high output air flow on the other, with instantaneous response.  By using a pressure regulator, available as part of a kit or separately, the flow of the material transfer can be easily controlled. No moving parts or electricity assures maintenance free operation!

lvmatrix
Trim Scrap Removal

Conveyance rates are determined by the material bulk density, typical particle size, total distance of conveyance, including vertical rise, and the targeted transfer rate.  An EXAIR Application Engineer can assist you, and with the above information, recommend the right size and type of Line Vac to meet the desired results.

All catalog models are in stock and we ship same day with an order received by 3 pm EDT in the US and 2 pm EDT for orders shipping to Canada.

Our team of engineers can design a special Line Vac to meet many applications special requirements, from special materials such as PVC and PVDF to special end connections such as pipe flanges and barbed hose connections.  Let us know the special requirements of your process and we’ll design a solution.

Special Flanged LV
This special 3/4″ Line Vac was designed to evacuate fumes from a silicone wafer etching operation

To go with the Line Vac, we can provide a reinforced, heavy wall, clear PVC conveyance hose in lengths up to 50′.  Additionally, the Line Vac Drum Cover is a fine mesh, non-woven cover built to fit on the top of a 30 or 55 gallon drum.  It is designed to contain the material to the drum and allow the air from the Line Vac to escape.

6850drumcover
Drum Cover, for 30 and 55 Gallon Drums

If you have questions regarding the Line Vac, or would like to talk about any EXAIR Intelligent Compressed Air® Product, 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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Twitter: @EXAIR_BB

There’s More Than 1 Way To Blow Some Air

Just today I spoke with a customer who is threading the ends of pipes and needs to blow the coolant and chips out of the threads.   The pipes range from 4″ to 9 – 5/8″ Diameters.  They are all threaded then fed into a trough and pushed down line to the next operation.

PEO ACWA
A machine with an out-feed roller conveyor similar to the pipe threading machine mentioned.

The photo above is not the exact machine but you can see where if this was used to process piping the different diameter pipes would all sit at the same level.  One option could be to use a Super Air Wipe  for this application but then the smaller diameters would not pass through the center of the Air Wipe, instead they would pass through the bottom half of the airflow which may not give optimal performance. Instead, I suggested to use 4 of our 6″ Super Air Knife kits and 2 of our Electronic Flow Control units.

 

2 - 110006 - 6" Aluminum Super Air Knives coupled together w/  a 110900 SAK Connector Kit
2 – 110006 – 6″ Aluminum Super Air Knives coupled together w/ a 110900 SAK Connector Kit

I  suggested that we make two pairs of knives for this blowoff setup by coupling two of the 6″ Super Air Knives together.  Once they are coupled together like is shown above, we could mount the two coupled air knives vertically along the trough and blowing at a 45° angle toward the center of the conveyor.  The plumbing of the two bottom knives will be to one EFC while the top two knives will be plumbed to the other.    The sensors will then be set up at two different heights, lower knives to sense the bottom of the pipe and the upper knife sensor will be set just above the bottom 6″ knife.

The reason for using 4 – 6″ Super Air Knives and 2 EFCs instead of 2 – 12″ Super Air Knives and 1 EFC is to save the most compressed air possible.   By enabling them to turn the top two 6″ Super Air Knives off automatically when they are running below a 6″ diameter pipe.  Then when a larger pipe is processed the top knives will also kick on with the lower knives and provide a uniform blowoff of the product.

So if you have multiple sizes of product being processed on the same line and don’t think any one solution will work, contact us and see if we can’t come up with our own recipe.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF

 

Machine image courtesy PEO ACWA Creative Commons

 

Back At Ya!

This may not be big news as it happens almost every month.  EXAIR is continuing to grow our product line and this time it is something we have never done before.  This new EXAIR Engineered Solution doesn’t blow debris away, instead, it all comes back towards you.   Why would you want this you ask?  What does this new-fangled contraption look like?  Both of those questions will be answered below.

To answer the first question, why would you ever want debris to come back at you?  Well, this isn’t for just blowing any part or area out, this nozzle has been designed for a special purpose – to blow out pipes, tubes, extrusions, and even some blind holes or pockets.   This is ideal when working on a piping system that you may need to clean out and don’t want to push debris further into the system.   It is a quick and easy way to clean out chips from a saw cut operation for tubing or extrusion.  The nozzle could even be used to clean out cylinders or crank shaft openings on engine blocks.

So what is the name of this new nozzle and what does it look like?

What does it look like already!
What does it look like already!

 

The EXAIR Model 1006SS - Back Blow Nozzle
The EXAIR Model 1006SS – Back Blow Nozzle

This is it, the EXAIR model 1006SS Back Blow Nozzle.   The nozzle features a 1/4″ FNPT air inlet, a 3/4″ O.D. to fit into piping, extrusion, or holes, and two flats which allow for the use of a 5/8″ wrench to install the nozzle.   The nozzle is constructed of 316 Stainless Steel, utilizes  22 SCFM when operated at 80 psig, gives off 80 dBA and is designed for use with 7/8″ to 4″ I.D. pipe, tube, or holes.

The unit will also be available on our Safety Air Guns with Chip Shields to offer cleaning excellence and protection for the operators.  Like all of the stock EXAIR products, this is available with our 30 day guarantee.   So if you are not sure whether this nozzle will work on your application, give us a call, get one in, and put it through the paces.   If the Back Blow nozzle doesn’t meet your needs, simply let us know within 30 days from the date of purchase and we will take it back and provide you full credit.

If you want to discuss this nozzle or any other compressed air application, don’t hesitate to contact us.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF

 

Finger Face – Tsahl Levent-Levl , Creative Commons License, Some Rights Reserved

 

 

 

Video Blog: Adjusting a Vortex Tube

See how simple it is adjust the outlet temperature of an EXAIR Vortex Tube below zero degrees Fahrenheit.  Vortex Tubes  are a low cost, reliable maintenance free solution for many industrial spot cooling applications.

EXAIR Vortex Tubes are constructed of stainless steel to resist corrosion and oxidation for years of reliable, maintenance free operation. They are used to provide cooling for electronic controls, dry machining operations, cameras, sensors, CCTV, hot melt adhesives, soldering, brazing, gas sampling, heat seals, and environmental chambers.

There are many advantages when using Vortex tubes:

  • No moving parts
  • No electricity
  • No chemicals
  • Low cost
  • Maintenance free
  • Instant cold air
  • Easily adjusted for temperature

Dave Woerner
Application Engineer
Davewoerner@EXAIR.com
@EXAIR_DW