How to Choose a Pneumatic Tube Based on Material and Application
Pneumatic systems require the correct choice of tubing to function correctly. There are a number of choices including polyurethane (PU), nylon and polyethylene tubes and the choice between them is heavily influenced by the application and environment in which the system is to function. In addition to safety considerations the choice of pneumatic tube will also have a significant bearing on the potential maintenance costs over time. In this article we shall examine the key factors that influence the choice of pneumatic tubing and discuss the performance of polyurethane tubes in typical industrial applications.
What Factors Should Be Considered When Choosing a Pneumatic Tube?
The choice of the correct pneumatic tube depends on a number of technical parameters with a bearing on the operational reliability.
Material Compatibility and Chemical Resistance
There are many different tubing materials that react differently with oils, solvents and moisture. Polyurethane tubing is very flexible and offers average chemical resistance. It is best suited for dynamic applications such as automated machinery or robotic systems. The Nylon tubing is suited for high pressure applications. However, it has a tendency to absorb moisture over time, which can affect the mechanical properties of the tubing. Polyethylene tubing is resistant to many chemicals but does not have enough flexibility for applications with moving parts.
Temperature and Pressure Requirements
Pneumatic tubes have specific Temperature and pressure ratings to enable safe operation. For typical applications of factory automation, PU pneumatic tubes operate between -20°C and +60°C. Tubes made of reinforced nylon or polyethylene may be needed for higher temperatures or for higher pressure applications such as automotive paint lines or compressed air manifolds. Selecting a suitable tube for the pneumatic system is critical to prevent damage and costly down-time. It is particularly important to match the selected tube with the compressor’s output pressure.
Mechanical Properties and Flexibility
The mechanical properties of tubing are critical both in terms of the installation and subsequent service life. Polyurethane tubing for example is flexible at very low temperatures thus minimising the risk of kinking when routed through small aperture installations. Nylon tubing on the other hand is stiffer and thus provides greater dimensional stability for fixed install situations where minimal movement is allowed to occur. The bend radius for tubing should thus be reviewed against the specific installation layout to avoid leakage or premature fatigue cracks.
How Does the Application Environment Influence Tube Selection?
The environmental conditions in the pneumatic system generally specify which material is best to use.
Industrial Automation Systems
In robotic arms or conveyor systems where motion is frequent, PU pneumatic tubes are preferred due to their elasticity and abrasion resistance. Their ability to withstand repetitive bending without cracking ensures consistent airflow delivery across thousands of motion cycles—a key factor in maintaining precision in automated assembly lines.
Food and Pharmaceutical Applications
For hygienic industries like food packaging and pharmaceuticals, tubing has to meet FDA or EU food-grade standards in order to avoid contamination. We recommend non-toxic polyurethane tubing that is certified for cleanroom use and is flexible, non-reactive and smooth to prevent bacterial growth.
Harsh Outdoor Conditions
Exposure to outdoor installations involves tubing that is exposed to UV radiation, ozone and varying temperatures. Standard plastics have a relatively short service life when exposed to UV radiation. However, tubing made from UV-stabilized polyurethane can have a longer service life. In chemical plants or marinas with saltwater where there is a risk of corrosion by oil mist and ozone, tubing must be resistant to both.
Why Is Polyurethane Tubing Popular Among Pneumatic System Designers?
The balanced characteristics of polyurethane are the reason why it is used in so many industries.
Balance Between Flexibility and Strength
PU pneumatic tubes have elasticity and sufficient burst strength for medium-pressure applications, for example with air tools or actuators. Their soft outer surface makes it easy to route the tube through confined spaces within a machine. Also installation in machinery is easy because no special tools are required.
Cost Efficiency Over Lifecycle
Although polyurethane may cost a little more than the initial cost of PVC alternatives, the increased durability of polyurethane means that it will have to be replaced less often. According to the European Fluid Power Association (EFPA) this can be up to 30% less. When you include the cost of labor for maintenance shutdowns the longer life form of polyurethane will lead to considerable savings in the long run.
Noise Reduction and Vibration Damping
The benefit of polyurethane over other rigid plastics, such as nylon, is its ability to absorb vibration. This damping quality of polyurethane helps to reduce noise levels in the compressed air system. In precise assembly lines and laboratories, where work is extremely fine, controlling sound in the air system is critical to the operator’s comfort as well as to the accuracy of his or her measurements.
How Do Installation and Maintenance Practices Affect Tube Performance?
How a pneumatic tube system is handled during the installation is key to the item types it will be used for in getting the maximum life from the system.
Proper Cutting and Connection Techniques
When cutting PU tubes, it is very important to make clean cuts using sharp tools to prevent the material from developing micro-cracks. These micro-cracks can then propagate under pressure cycling. To connect PU tubes, use compatible fittings made of brass or stainless steel to prevent deformation of the soft wall material. The fitting will maintain a tight seal even when pressure is fluctuating.
Routine Inspection Schedules
Every 6 months check your oil mist filters for signs of wear like discoloration or hardening due to heat. Also regularly clean off any dust that has accumulated on the outside of your air flow surfaces. Blocked air passages can decrease system output by as much as 10%.
What Are Common Mistakes When Selecting Pneumatic Tubes?
Not even experienced engineers can always remember everything important to select the right components.
Ignoring Environmental Factors
The use of non-resistant materials in oil, chemical exposed environments will decrease greatly the service life of the tubing. For example standard PVC tubing will go brittle within a few months in hydraulic oil environments, in contrast to polyurethane which is able to withstand for many years in the same environments.
Overlooking Pressure Ratings
Using low-rated PU tubing in high-pressure circuits can cause the tubing to balloon and even burst under load, a common cause of sudden failure that can cause damage to surrounding components.
Neglecting Maintenance Costs in ROI Calculations
When calculating return on investment (ROI), it is important to include items such as replacement interval, downtime lost, and reinstallation labor in addition to the purchase price per meter. Although the initial investment may be higher, the total cost of ownership can be lower over several years of continuous operation when viewed in the long term.
Who Is Yantai Aisili New Material Co., Ltd.?
Yantai Aisili neue Material Co., Ltd. is a pneumatic tubing products manufacturer specializing in polyurethane (PU) , nylon (PA) and polyethylene (PE) products. Our products are used in automation, robotics, packaging and automotive assembly lines all around the world. We are an ISO9001 registered manufacturer, and we have a quality management system in place to ensure consistent quality in all our production batches. Our services include custom made pneumatic tubing products through extrusion, to your exact specifications, including diameter and hardness. We can also provide you with technical advice on fluid compatibility, help with tubing layout, advice for installers and we have a worldwide logistics network to ensure a stable supply to our OEM customers and partners. We offer long term partnerships and excellent quality products made to last.
Conclusion
The selection of pneumatic tubes, in terms of their material, is a trade-off between good properties of the material and the various demands put on it in terms of environmental conditions, costs and maintainability. For dynamic applications in industry polyurethane tubes are the most suitable. The tubes can render long and stable service, provided they are correctly installed and are regularly inspected. From an engineer’s perspective it is ideal to work together with suppliers who are technically qualified, such as Yantai Aisili New Material Co., Ltd. This way the quality of the pneumatic tubes can be guaranteed, and the costs for the lifecycle of the tubes can be kept under control. This applies to various types of manufacturing facilities.
FAQs
1. What is the typical lifespan of a polyurethane pneumatic tube?
Under normal operating conditions, properly installed PU pneumatic tubes have a typical lifespan of 3 to 5 years, depending on pre-installation practices and ongoing inspection.
2. Can PU tubes be used with oil contaminated compressed air?
Yes – PU tubes are relatively insensitive to moderate amounts of oil. However, large amounts of oil in the air can cause the PU tube to loose flexibility over time. An inline filter can be installed to protect sensitive components.
3. Is polyurethane suitable for vacuum applications?
Polyurethane tubes are suitable for light vacuum applications, however normal polyurethane tubes may collapse when deeper vacuum is applied. For these deeper vacuum applications we recommend a reinforced version of polyurethane tubes.
4. What size is the correct inner diameter for my system?
To calculate the required inner diameter for your system on the basis of the required flow rate. Too small tubes increase the pressure drop, too large tubes waste energy and decrease the velocity efficiency in your system.
5. When buying pneumatic tubing what quality certifications should I look for?
Look for ISO9001 quality certification and RoHS or REACH compliance documentation to confirm that the materials used in the tubing are safe for use in industry on an international basis.