Pneumatic hoses and tubing
Figure 1: Pneumatic hoses and tubing
Pneumatic hoses and tubing are essential components in a wide range of applications, from industrial automation to medical devices. They transport compressed air to power tools, actuators, and other pneumatic equipment. The choice of hose or tubing depends on the specific application and the required performance characteristics. This article explores the different types of pneumatic hoses and tubing, their properties, and their applications.
Chemical resistance of tube and hose materials
Compressed air contains by-products such as compressor oil, dust particles and condensate. The environment also needs to be taken into consideration. The hose or tube materials need to be resistant to all these substances and conditions. For hoses and tubes, a slightly different definition is used.
When referencing a tube, they are typically monolayer. This means that they are made from one material. This one material needs to be chemically resistant to both the compressor oils and condensate from the media while being protected from any environmental conditions.
When referencing a hose, these can be made from multiple layers of materials. You can therefore ensure that the inner hose material is resistant to the compressor oils and condensate, but can then have a second material as the outer shell to protect it from environmental conditions.
The majority of pneumatic tubing and hosing is made of thermoplastics. As discussed, they can be monolayer or multi-layered depending on the application. Below we briefly discuss the most common thermoplastics that are used specifically for pneumatic tubing. However, please read our hosing and tubing materials and see our chemical resistance chart for additional material information.
- Polyurethane (PUR or PU): Kink and abrasion resistant, flexible, and strong.
- Polyamide (PA or Nylon): Light, robust, dimensionally stable, good bend radius, good flexural-fatigue resistance, and a low moisture absorption rate.
- Polyethylene (PE): Flexible, good chemical resistance, and is cost-effective.
- Polyvinylchloride (PVC): Light, flexible, and can be repeatedly sterilized with no ill effects.
- Polypropylene (PP): Very light, good chemical and heat resistance, and has good surface hardness.
Main air supply
Figure 2: Pneumatic components like valves, cylinders, or pressure regulators are typically connected to the main air supply line via flexible tubing or hoses.
To distribute the compressed air from the compressor to the application, either pipework or hoses are used.
For large industrial workshops, there is often a requirement to have multiple connections throughout the workshop to connect pneumatic tools. In these settings, usually, a rigid piping system is used because it offers protection against accidental impacts or puncture. These rigid pipe systems, however, are expensive and labor intensive to install. As durability is a key criterion, often aluminum, copper, stainless steel, or rigid PVC is used. They also require numerous fittings and joints, which increases the points of possible leakage. The environmental temperature also needs to be taken into consideration as pipework can expand and contract with a temperature change. For example, aluminum expands 0.24 mm per meter pipe for every 10°C temperature increase. It is therefore important that the piping system is routed taking these movements into account, for example by using expansion loops.
Air supply lines
Flexible hoses are used in conjunction with rigid piping of the compressed air or by itself in smaller workshops. They are also used for temporary or mobile air supply. Because flexibility, ease of installation, and durability are important in these applications, often lightweight HDPE is used or heavy rubber lines. Flexible hoses also allow for fewer fittings when compared to pipework and there is less concern of temperature impact due to it not being rigid.
Air supply to components
Pneumatic components like valves, cylinders, or pressure regulators are typically connected to the main air supply line via flexible tubing or hoses. However, they can also be reinforced, like a metal-plastic pipe as this allows for durability along with it being light and flexible. Flexibility is important due to the components could be vibrating or moving, so having a flexible hose will account for this. They are also at the end of the pneumatic cycle, they can have the smallest needed diameter. They are connected to the main air supply line and individual components via fittings. To understand how to select a fitting, please read our fitting article. Common fittings are barbed fittings, compression fittings, or instant fittings (also called ‘push-in’ or ‘push-to-connect’). A push-to-connect fitting is the most common as it is easy to connect and disconnect different lines when needed.
To maintain a safe work environment and to ensure no damage is done to the hose, they are often stored on reels or they are coiled.
Air hose reels
An air hose reel is a cylindrical spindle used to store a hose. Usually, they are mounted to the wall, ceiling or to the floor. They help to keep the hose organized and to avoid any kinks. Often, they are self-retracting with a spring driven mechanism, but they can be hand cranked as well. Usually, air hose reels are used in combination with pneumatic tools or any other application that requires only a temporary supply of compressed air. The hose is typically made out of rubber, PU, or PVC.
The mechanism of a self-retracting hose reel works by pulling out the hose until the desired length is achieved. The hose reel will make a rattling sound when unwinding, which means you can lock it into position by releasing it. To trigger the spring loaded self-retracting mechanism, the hose needs to be pulled slightly outwards. During the retraction keep hold of the hose until it is fully retracted. Never let it go during retraction as the whipping end of the hose could cause injuries or damage.
A hose reel offers the advantage of automatically storing a hose and ensures a tidy and safe working environment. This also prevents any premature hose failure to due wear from being stepped on, dragged, or accidently hit from something in the environment (another tool, vehicle, etc.)
Coiled air hose
Coiled air hoses are often used in garages and workshops for supplying air to pneumatic tools such as impact wrenches, blow guns etc. They are light and self-retractable, so they do not take up a lot of space. The hose is usually not coiled all the way to the fittings. On both sides a small straight part is left, which is called a tail. The difference between the extended and retracted length depends on the coil diameter. For a standard coiled air hose, the extended length can be for example ten times the retracted length. In order to produce a coiled air hose, the hose material needs to have a good elastic memory to return to their initial coiled form after being straightened. Therefore, rubber is not used and typically Nylon, PU, or PVC are used for these applications.
Figure 3: A coiled hose is often used in workshops with pneumatic tools
What is a pneumatic hose?
A pneumatic hose distributes compressed air to pneumatic components likes actuators and valves.
What is polyurethane tubing used for?
Polyurethane (PU) tubing is a the most common type of tubing used for pneumatic applications. The PU material makes it durable, gives it good resistance to kinks and abrasions, and it is readily available.
What is PE tubing?
PE (Polyethylene) tubing is the second most common tubing type used for pneumatic applications. The PE materials makes it light, cost-effective, flexible, and a perfect solution for low-pressure applications.