The selection and design of hose systems require not only consideration of the nominal pressure and the medium but also the operating temperature. An often underestimated factor: as temperature increases, the mechanical strength of the hose material decreases—and with it, the permissible pressure load.
Why does pressure resistance decrease with heat?
Most hose materials are made of plastics, elastomers, or rubber. These materials are sensitive to temperature changes:
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At high temperatures, elasticity decreases, molecular structures loosen, and resistance to internal pressure drops.
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At low temperatures, however, the materials become harder—making them more brittle, but also more pressure-resistant.
This means that temperature has a direct effect on the maximum permissible operating pressure.
Pressure reduction factor depending on temperature
The reference value for pressure resistance is at +20 °C = 100%. Deviations above or below this temperature affect the permissible operating pressure as follows:
| temperature | Permissible operating pressure (in % of the initial value) |
|---|---|
| –20 °C | 145 % |
| –10 °C | 135 % |
| 0 °C | 120 % |
| +10 °C | 110 % |
| +20 °C | 100 % |
| +30 °C | 85 % |
| +40 °C | 73 % |
| +50 °C | 60 % |
| +60 °C | 46 % |
Example: If a hose has a pressure resistance of 10 bar at +20 °C, it may only be operated at 6 bar at +50 °C.
Important notes for practical use
- Plan safety margins: Especially in applications with strongly fluctuating temperatures, an additional safety factor should always be taken into account.
- Adjust material selection: Depending on the medium and temperature range, a specific hose type (e.g. high-temperature or low-temperature hose) may be required.
- Check sizing: Even short temperature peaks can significantly shorten the service life.
Conclusion
Temperature is a crucial factor in the design of hose systems. Only those who take pressure reduction values in relation to temperature into account can ensure safe and durable operation.
