There are a variety of materials available to connect cylinders and valves in modern pneumatic systems. Some people use flexible pneumatic tubing while others prefer to use hoses.
The basic purpose of hose and pneumatic tubing is to carry compressed air to valves, actuators and other devices. Flexible tubing is a popular choice when it comes to connecting cylinders and vacuum generators in automated equipment, and hoses are a close second. Irrespective of the tubing, it’s vital to not confuse the internal diameter with the outside diameter.
Let’s look at the differences between the two widely used tubing materials in terms of their designs and implementation.
Tubing for pneumatic applications is usually an extrusion of nylon, polyurethane, special material like PTFE or reinforced internally with textile fibers for added strength.
Pneumatic hose, on the other hand, is manufactured by adding nylon braids between the outer and inner layers of tubing, in addition to attaching a swivel and rigid fitting. Although, hose is more expensive than tubing, it is also more rugged and flexible.
The size of the tubing or hose is determined based on the flow requirements. Tubing is specified by the Outside Diameter (OD) and the wall thickness—for compatibility with push-fit pneumatic fittings, while hose is specified by its Inside Diameter (ID).
Regardless of the tubing type, keep in mind to check the diameters carefully to ensure proper flow; too small of an inner diameter can choke the flow and result in excessive fluid velocity, pressure loss and inefficiency. On the other hand, too large a diameter results in unnecessary increase in size, weight and cost.
Generally, the outside diameter drives the specification process in machine shop applications and automated equipment. If you require more air flow, the obvious choice is to opt for a larger diameter.
Tubing is mostly used with push to connect, push lock or other similar fittings since it is specified by the outside diameter.
Since hoses are integrated with nylon braids, they provide added strength, making them ideal for manual operations where they may be dragged across the floor. Some hoses are made with lighter weight polyurethane and some are made with heavier rubber. However, there’s one thing common in all hoses: they are all kink resistant. This makes them a good choice for blow guns and pneumatic tools.
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