Polyurethane Tube Hardness Selection Errors: Three System Problems Engineers Often Overlook

Feb 12, 2026

Selecting the correct tubing hardness is a critical part of PU Air Tubing Selection in pneumatic automation systems. When the hardness of a PU Pneumatic Hose does not match the operating conditions, system performance can gradually decline without obvious early warning signs. Incorrect hardness choice commonly leads to pressure instability, delayed actuator response, and accelerated wear—issues that significantly increase maintenance costs in long-term industrial operation.

Expansion and Pressure Loss Caused by Incorrect Hardness

When tubing hardness is too low for the working pressure, the Industrial PU Hose may expand slightly under compressed air load. Even small dimensional expansion can cause measurable pressure drop across long pneumatic lines, reducing actuator efficiency. In high-cycle systems such as packaging or assembly machines, excessive tube expansion leads to unstable pressure delivery, affecting repeatability and process accuracy.

High-pressure routing or long-distance pneumatic distribution typically requires higher-hardness tubing such as 98A PU Tubing, which maintains better dimensional stability during operation.

Response Delay in Pneumatic Actuation Systems

Another frequent issue appears in motion-control applications. Softer tubing stores more elastic energy during pressurization, meaning part of the compressed air energy is temporarily absorbed by tube expansion instead of immediately driving the actuator. This results in slower cylinder response and inconsistent timing, particularly noticeable in synchronized multi-axis equipment.

In automation systems requiring precise timing—robotics, pick-and-place units, and high-speed sorting lines—engineers often prefer Industrial PU Tubing with higher Shore hardness to minimize elastic delay and improve control precision.

Accelerated Wear in Dynamic Motion Installations

In dynamic installations such as cable carriers, tubing is exposed to continuous bending and friction. If hardness is too low, the outer wall of a Drag Chain Polyurethane Tube can wear rapidly due to repeated contact with the carrier track. Over time, this leads to thinning of the tube wall and eventual leakage.

Higher-hardness polyurethane tubing significantly improves abrasion resistance, making it more suitable for moving automation equipment and robotic motion systems.

Typical System Risks Caused by Incorrect Tubing Hardness

The table below summarizes the most common system issues observed in industrial pneumatic installations:

Hardness Selection Issue	System Effect	Typical Result	Recommended Adjustment
Tubing too soft for pressure	Tube expansion	Pressure instability	Use 95A–98A tubing
Tubing too elastic for control systems	Response delay	Slower actuator timing	Select higher Shore hardness
Tubing too soft for moving systems	Surface abrasion	Early leakage	Use drag-chain-grade tubing

Performance ranges based on industrial pneumatic application experience.

Practical Selection Guidance for Engineers and Buyers

Correct tubing selection requires matching hardness with pressure level, motion frequency, and installation environment rather than choosing based solely on flexibility. For static installations, medium hardness tubing often provides sufficient performance, while high-pressure lines or dynamic routing systems benefit from high-durability PU Pneumatic Hose grades.

Many equipment manufacturers standardize multiple hardness levels across the same machine—for example, flexible tubing in tight routing areas and 98A PU Tubing in long-distance or high-wear sections—to balance installation convenience with long-term reliability.

(FK9026)

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