## The Difference Between a Hose and a Tube and Their Effect on Pressure Drop

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 performance 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 source to the point-of-use. 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, the inner diameter of 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 cut waste, we need to reduce pressure drop.  If we look at the equation for pressure drop, we can find the factors that play an important role. Equation 1 shows an equation for pressure drop.

Equation 1:

From Equation 1, differential pressure is controlled by 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 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.

As an example, we have a 1/2″ black schedule 40 pipe which has an I.D. of 0.622″.  We use this pipe to flow 40 SCFM of compressed air at 100 PSIG through 100 feet.  What would be the pressure drop?  With Equation 1, imperial units, we get a pressure drop of 1.28 * (40 SCFM/60) ^1.85 * 100 feet / ((0.622″)^5 * 100 PSIG) = 6.5 PSID.  Thus, you started with 100 PSIG, and at the end of the pipe, you will only have (100 PSI – 6.5 PSI) = 93.5 PSIG to use.  Sizing pipe is very important when supplying compressed air to your system as pressure drop is a waste of energy.

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.

Equation 2:

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.  As an example, if the pressure drop through a 3/8″ hose is 1 PSID, and you decide to switch out to a 3/8″ tube.  The pressure drop will then be 7.6 PSID, and a big loss of pressure.

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. (You will have to sign into the website to download).  We also have 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 waste from pressure drop and get the most from your 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 could be the reason for under performance of your pneumatic products, as well as wasting money within your compressed air system. If you would like to discuss further the ways to save energy and reduce pressure drops, an Application Engineer at EXAIR will be happy to help you.

John Ball
Application Engineer
Email: johnball@exair.com

Photo: Manometers by WebLab24_Siti_Web . Pixabay License

## Are EXAIR’s Hoses and Tubes Right For You?

Are you tired of ducking and dodging hard pipe everywhere? Do you need something more mobile for your compressed air? Then EXAIR Hoses and Tubes might be a solution for you. EXAIR offers a variety of hoses and tubes in different styles designed to work with our products without affecting performance. These products simplify the use, setup, and integration of our various products into your process. Normally if you were to buy hoses you would need to determine the proper diameters, pressure ratings, and/or end fittings to best fit the item in use. This is all unnecessary when purchasing EXAIR’s Hoses and tubes for EXAIR products since everything is sized and properly rated to be used with our products. So, ask our Application Engineers if EXAIR Hoses and Tubes are right for you.

Products may include the following.

These hoses are used with our Air Operated Conveyors or Line Vacs which are used to convey material from point A to point B. The hose can be mounted on either side of the Line Vac using the properly sized hose clamp that comes with it. The Conveyance hose is made out of a durable PVC semi-flexible material in sizes from ¾” I.D. to 3” I.D. to match our Line Vac sizes. They also come in lengths up to 50’ in increments of 10’.

When it comes to getting compressed air to our safety air guns, we offer a series of abrasion-resistant nylon Coiled Hoses. The coiled hose comes in a 12’ long length and comes in 3 sizes; these sizes are 1/8” NPT, ¼” NPT, and 3/8” NPT to attach right to EXAIR’s Safety Air Guns. The hoses also include swivel fittings to make for easier uncoiling. The coiled design makes it easy to reach around the work area and retract back to the substation. With the right size hose Coiled Hoses can supply the required amount of compressed air with minimal amount of pressure drop.

Compressed Air Hose can be used to reach equipment from overhead or near equipment. These hoses are made with synthetic rubber and comes in 3/8” I.D. and ½” I.D… Lengths up to 50’ long can be provided and the hoses are rated for up to 250 psig air pressure. These hoses can provide lasting protection from ozone, weathering and temperatures up to 158oF. They also come with two male ends in ¼” NPT or ½” NPT.

Bendable and flexible, the stay set hose allows for manual positioning of your compressed air product. Equipped with “memory” function, the hose will not creep or droop until it is physically moved. The Stay Set Hose comes in lengths from 6” to 36” in length, and they offered in a combination of 1/8” and ¼” MNPT connections. These hoses are rated for 250 psig and are made of a reinforced rubber.

Vacuum Tubing:

When it comes down to our E-Vac product line, EXAIR offers vacuum tubing to be used along with the unit. This tubing is made from polyurethane and comes in 1/8” O.D. and 3/8” O.D. up to 50’ in length in increments of 10’.

If you have any questions about compressed air systems or want more information on any of EXAIR’s products, give us a call, we have a team of Application Engineers ready to answer your questions and recommend a solution for your applications.

Cody Biehle
Application Engineer
EXAIR Corporation
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## EXAIR Hoses and Tubes are Great Accessories

EXAIR offers different styles of hoses and tubes as accessories to our product lines.  They are built and designed to easily fit with our products as well as being sized correctly to not affect performance.  It simplifies the use, setup, and integration of EXAIR products in your facility.   You do not have to determine the proper diameters, pressure ratings, or end fittings to best fit the EXAIR products to maximize their performance.  Also, having these items available from one source minimizes the number of purchases and vendors necessary for a complete and working solution. In this article, I will go over the different hoses and tubes that EXAIR can provide.

Conveying Hoses:

The hoses above are used with our Air Operated Conveyors or Line Vacs.  The Line Vacs are designed to move product from point A to point B.  If the Line Vac is the “vehicle”, the Conveyance Hose is the track.  The hoses are made of a durable PVC semi-flexible hose with 6 different diameters from ¾” I.D. to 3” I.D.  The conveyance hose can slip easily onto the EXAIR non-threaded style of Line Vacs.  EXAIR can cut-to-length Conveying Hoses up to 50 feet (15m); in increments of 10 feet (3m).

Coiled Hoses:

To get compressed air from the piping system to the Safety Air Guns, we offer a series of Coiled Hoses.  They are made of a durable abrasion-resistant nylon material that is 12 feet long (3.6 meters).  They have swivel fittings to allow for easy uncoiling, and a spring strain relief to keep the hose from kinking.  The coiled design makes it easy to reach around the work area and retract back to the substation.  This will help to keep the hose off the ground where potential dangers could occur.  We offer 3 different connection sizes of 1/8” NPT, ¼” NPT, and 3/8” NPT to attach right to the Safety Air Guns.  With the proper size, the Coiled Hoses can supply the required amount of compressed air with a minimal amount of pressure drop.

Compressed Air Hoses:

If you need a compressed air line to reach from overhead or around equipment, the EXAIR Compressed Air Hoses would work with these applications.  They are made from a reinforced synthetic rubber in 3/8” I.D. and 1/2” I.D. diameters.  We can make specific lengths up to 50 feet (15m).  They are rated for 250 PSIG (17 bar) air pressure, and the hose material works well for long lasting protection against ozone, weathering and temperatures up to 158oF (70oC).  They come with two male ends in ¼” NPT or ½” NPT.

Stay Set Hoses:

The Stay Set Hose gives you that possibility of manually adjusting or re-adjusting Super Air Nozzles.  The hose has a “memory” function, and it will not creep or droop until you physically move it.  They work well to direct air flows in specific target areas.  They can be used with Super Air Nozzles, Safety Air Guns and Blow-off Kits.  The Stay Set Hoses come in lengths from 6” (15cm) to 36” (91cm), and they are offered with ¼” NPT male on both ends or with a 1/8” NPT female and a ¼” NPT male connections.  These hoses are rated for 250 PSIG (17 bar) and are made from reinforced synthetic rubber.  If positioning is required for accurate blowing or re positioning for different areas, the Stay Set Hose would be a nice addition to your equipment.

Vacuum Tubing:

For our E-Vac product line, EXAIR offers vacuum hoses to connect the E-Vac vacuum generators to the suction cups.  They are made from polyurethane in ¼” O.D. and 3/8” O.D.  The tubing is very flexible for moving product, and they can resist the vacuum pressures created by the E-Vac.  They slip easily into our Push-In Connectors to quickly attach vacuum cups to the E-Vac system.  EXAIR can sell both types of tubing up to 50 feet (15m) in increments of 10 feet (3m).

Hoses and tubes may seem like simple things, but EXAIR already did all the research in determining the best material and correct size for optimum performance.  You can leverage this information to save you time and money when using EXAIR products in your application.  If you need help in selecting the correct model, you can contact an Application Engineer.  We will be happy to help you.

John Ball
Application Engineer
Email: johnball@exair.com