How Does a Pneumatic Tube Work? Principles, Components, and Applications

It looks so simple – a pneumatic tube made of PU. And indeed, the pneumatic tube is probably the part of your pneumatic system that is most frequently contacted by air, by the machine it operates and by human hands. It can have a major effect on air delivery, on machine response, on the risk of leakage, on the cost of maintenance, on safety. And if you are a buyer from the U.S., an engineer, an automation contractor or a procurement person, you will need to check some important criteria of the PU pneumatic tube that you select. Will it withstand the working pressure of your system? What will be the minimum bend radius without risk of injury to the tube walls? What kind of fittings will you require? What are the required temperature characteristics? Are there any chemicals that the pneumatic tube will be in contact with? What are the specific installation requirements of your air system? 

How does a pneumatic tube move compressed air through a system?

Pneumatic tubing or air hose connects up the various components of a pneumatic system, such as air cylinders, grippers, pneumatic valves and other pneumatic actuators. The tubing carries the compressed air from a pneumatic compressor or air preparation unit through to the control valves and finally to the end effectors or devices.

How does air pressure create motion?

Compressed air stores energy under pressure. When a directional valve opens, air travels through the pneumatic tube into an actuator chamber. The pressure difference pushes a piston, turns a rotary actuator, or powers a vacuum generator.

Ensure airflow can reach component with minimal pressure drop. If hose is too small, too long, kinked, or leaking, actuator may not move or move slowly or inconsistently.

Why does tubing size affect performance?

The outer diameter of a tube is typically specified to match up with standard fittings, while the inner diameter is important for airflow. A larger ID allows more airflow, but requires more space and can be more expensive. A smaller tube is easier to run in very tight applications, but can become a restriction in high-cycle applications.

For Experienced Engineers tube size is generally checked against working pressure, required flow, cycle speed and inter-bay distance.

Which components work together with pneumatic tubing?

The pneumatic tube is only one part of the whole air circuit. This part performs only optimal if the other surrounding parts are matching.

What parts are usually connected by pneumatic tubing?

Typical standard components for air distribution systems are compressors, air dryers, filters, regulators, lubricators, solenoid valves, cylinders, fittings, manifolds, silencers and sensors. Most automation systems have tubing runs from the control cabinets to the mobile sections of the machines.

Make sure that the tube is the correct size to fit all connections: push-in fitting, threaded adapter, valve port and actuator connection. Incorrect fitting is one of the most common reasons for leaks.

How do fittings and routing affect leakage?

When installing push-in fittings a clean square cut to the tube is important. Angled cuts, scratches, oval local deformation or sharp bends near the fitting all reduce the sealing area.

Routing of tubing also plays a part in selection. Tubes should be routed to avoid sharp edges, hot surfaces, moving chains, crushing sections and excessive tension. If a tube is to be flexed repeatedly before installation then the bend radius and flexibility of the tube before purchase should be checked.

How should buyers compare PU, nylon, PVC, and multi-material pneumatic tubing?

The choice of material has a direct influence on flexibility, pressure resistance, abrasion resistance, chemical resistance and service life. Selecting tubing on the basis of color or price is not wise.

When is polyurethane tube a practical choice?

Polyurethane tubing is generally selected for flexible routing. Its compact outer diameter also makes it an ideal tubing for use in compact automation, for use on Robotic Arms, in packaging machinery and for other compressed air lines. Because PU tubing is not as stiff as other materials it lends itself well to tight tubing routing that other tubing would not facilitate.

The buyer will have to find out the working pressure, the temperature classification, the hydrolysis resistance, the resistance against oils, and the bending capability of the PU tubing. Not all PU tubes are suitable for every application.

When should buyers consider multi-material pneumatic tubing?

Multi-Material Pneumatic Tubing is a suitable option for installations where different areas of the installation require different applications such as flexible sections through machine areas, long straight runs through plant, outdoor exposure or higher chemical resistance. For tougher mechanical areas Nylon tubing can be used and for lighter duty, lower cost applications, PVC tubing is suitable.

A simple rule for choosing the correct outer tube is: select a tube material which corresponds to the real operating conditions and not solely to the printed catalog description.

What specifications should be checked before ordering pneumatic tubing?

It is recommended that before a purchase is approved by the buyer that a detailed specification sheet is requested. This will ensure that even though the tubing looks correct in delivery it will perform correctly in its installation.

Which technical data should be confirmed first?

The key characteristics for quoting are: outer diameter, inner diameter, working pressure, burst pressure, temperature, bend radius, material grade, hardness, color, length per roll, and fitting compatibility.

What installation conditions can shorten service life?

Typical factors that reduce service life of products are: heat, oil mist, UV exposure, water, chemicals, vibration, bending, etc. Lines that are installed in the area of welders, ovens, cutting tools or moving machine guards are subjected to special influences and need a special check.

Buyers should also ask whether the tubing is to be used for static routing or in cable carriers that move from time to time or in washdown areas or high cycle usage applications. The proper material and bend radius are critical in these applications.

Which safety and compliance points should buyers consider?

Tubing in a pneumatic system is subject to considerable pressure. That is why safety considerations cannot be brushed aside as trivial. Safety must be developed within the scope of a specific machine, site, and field of application and based on the relevant standards and general work place rules.

Which standards may apply to pneumatic systems?

This ISO 4414:2010 Standard specifies the general rules and requirements concerning safety for pneumatic fluid power systems and their components which are part of or attached to machinery. Participation in the development of this standard is voluntary; however, it may be made mandatory by contract, by project specification, by buyer specification, by local rules. (ISO)

For use in the workplace in the United States OSHA 29 CFR 1910.242(b) states that for cleaning with compressed air it should be reduced to a pressure less than 30 psi and used with appropriate chip guarding and personal protection. This OSHA standard deals with cleaning with compressed air and is not intended to apply to normal operation of pneumatic tubing.

What documents help reduce procurement risk?

Customers need to request information from potential buyers to decide whether to buy, such as a product datasheet, material statement, pressure rating, packaging details, test reports if they exist, and fitting compatibility information.

If the tubing is used in OEM equipment, additional documents may be needed for RoHS, REACH, food-contact review, color coding, private label packaging, or customer-specific inspection. Buyers should distinguish product material documents from factory certifications or supplier self-declarations.

How can Yantai Aisili New Material Co., Ltd. support pneumatic tubing buyers?

Yantai Aisili บริษัท วัสดุใหม่ จำกัด, which is doing business through Aisili Pneumatic in Internet, is a leading company in China which specializes in designing and manufacturing high quality polyurethane pneumatic tubing, PU hoses, pneumatic fittings, etc. for industrial automation. On the website of the company, custom polyurethane tubing and pneumatic fittings are presented which are used for global industrial automation applications.

When comparing our pneumatic tubes made of PU to those of competing companies, our company is able to support with selection of tubes, colors and dimensions as well as discuss OEM branding and communicate in case of large orders.

Conclusion

A pneumatic tube works by carrying compressed air between system components so actuators and valves can operate correctly. The best tubing choice depends on material, size, pressure, bend radius, temperature, fittings, routing, and maintenance conditions. A polyurethane tube is often useful for flexible automation layouts, but buyers should still check the actual working environment before ordering. Standards such as ISO 4414:2010 and OSHA rules may be relevant depending on system design and workplace use. A careful specification review can reduce leakage, downtime, replacement cost, and supplier disputes.

FAQs

1. What is a PU pneumatic tube used for?

Pneumatic tubes made of PU are used to transport compressed air between pneumatic components such as air valves, connections, pneumatic cylinders and other pneumatic elements in automation, packaging machines, assembly lines and compressed air systems of all kinds.

2. How do I choose the right pneumatic tube size?

Check the OD of hose to fit connectors, check ID of hose to get correct airflow. Check the pressure rating of hose, the length of hose, the bend radius, and the required speed of actuator.

3. Is polyurethane tube better than nylon tubing?

That would depend on your application. In general the polyurethane tube is the more flexible of the two. However for more arduous mechanical applications or where you have long straight runs of tube then nylon may be more suitable.

4. What causes pneumatic tubing to leak?

Some of the most common errors are made with the cutting of the tube, incorrect tube size selected, dirty surfaces, worn fittings, over bending, heat damage and incorrect installation. A simple square cut and correct fitting are all that is required!

5. What should I ask a pneumatic tubing supplier before ordering?

Material type, size tolerance, working pressure, burst pressure, temperature, bend radius, fitting configuration, packaging details, MOQ, lead time and documents available.