Proper hose selection is critical to realize a safe hydraulic system. The first step in having a safe hydraulic system is selecting components that meet the needs. Compromises in hose selection may create situations of danger, as well as affect the performance and durability of the system. The choice may work for the short run, but may not be a good long-term decision. This guide uses the STAMPED process. STAMPED is an acronym that stands for the 7 major information areas required to provide a quality hose assembly, and in this post, we’re talking T for Temperature.
Temperature: Temperature of both the fluid conveyed and environmental conditions
Two areas of temperature must be considered: fluid temperature and ambient temperature. The hose selected must be capable of withstanding the minimum and maximum temperature seen by the system. Care must be taken when routing near hot manifolds and in extreme cases a heat shield may be advisable.
- Maximum Intermittent Ambient Temperature: Hose constructions which use a rubber inner tube and/or cover can have significant change in properties when exposed to extreme heat or cold. This may require some hoses to be rated to a lower operating pressure when exposed to such conditions.
- Fluid Temperature: The fluid temperature is the temperature of fluid being conveyed inside of the hose during operation.
- Ambient Temperature: The ambient temperature is the temperature of the environment to which the hose assembly is exposed.
- Maximum Temperature: The maximum temperature is the highest temperature to which the fluid or environment may reach. This temperature is typically short in duration and occurs under extreme operating conditions. The hose selected for an application should be rated at or above the maximum ambient and maximum fluid temperature.
- Minimum Temperature: The minimum temperature is the lowest temperature to which the hose assembly will be exposed. For a hydraulic system, this is based on the minimum ambient temperature. A hose should be rated at or below the minimum ambient temperature to which the assembly may be exposed.
- Maximum assembly working pressures will decrease as temperatures increase.
Temperature derating factors for hose assemblies
Temperature directly affects maximum allowable working pressure. Most manufacturers rate maximum operating pressures at an ambient temperature of 70 degrees F. If a hose is to be considered for use in an application that exceeds this ambient temperature, consult manufacturer for any pressure derating of the hose assembly.
The above is an excerpt from NAHAD’s Hose Safety Institute HANDBOOK, which provides performance standards for hose assembly specification, design, handling and management.
For a general overview on STAMPED, check out this post: What does STAMPED stand for?
For a more in depth look at the effects of extreme cold on hydraulic hose, check out this post: How does extreme cold affect hydraulic hose?
Hose Safety Institute
http://associationdatabase.com/aws/NAHAD/pt/sp/memservices_hsi
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