By: Frank Caprio | On: April 22, 2016
Once you’ve determined your application requires a metal hose, the next step is selecting a metal hose to ensure the assembly will safely meet the rigors of each application. When selecting a hose, physical specifications (length measurements, hose and fitting sizes, etc.) are always important, but you must also consider these three variables: pressure-carrying capability, flexibility, and chemical compatibility.
1. Pressure-Carrying Capability
The metal hose must be strong enough to handle the pressures to which it will be exposed. To determine hose pressure capability, consult the catalog for the “Maximum Working Pressure” stated for the hose. The Maximum Working Pressure must be reduced for each of the following circumstances:
- Temperature – As temperature increases, hose working pressure decreases. After you have determined the proper alloy (see “Chemical Compatibility” below) go to the “Derating Factor” table in the Technical Information section of our catalog and match the alloy of the hose and braid with the highest temperature to which they will be exposed (either internally or externally) to obtain the proper derating factors. Then multiply the hose’s Maximum Working Pressure by the most-limiting temperature derating factor.
- Dynamic Pressure – Pulsating, surge, or shock pressures, like those encountered with quick opening or closing valves, can inflict severe damage on a metal hose. If your application entails pulsating pressures, the working pressure should be derated by half. If your application entails shock pressures, derate the stated working pressure to 1/6 of its value.
Step 2 in selecting a metal hose is confirming that the hose’s minimum bend radius (see the catalog) is less than the bend radius required for the application. Increasing the installed radius of the hose will reduce fatigue on the corrugations, increasing assembly life. Care should also be taken for applications with vibration. Contact Hose Master’s Inside Sales team if excessive vibration is present. We can help you to navigate this challenge.
3. Chemical Compatibility
You must choose a material for the hose and braid that is compatible with the media being conveyed through the hose, as well as the environment in which the hose is to be installed. When determining chemical compatibility, it is important to know the temperature and concentration of the chemical(s). Although there are many resources to confirm chemical compatibility, two of the industry standards that you may use are the National Association of Corrosion Engineers (NACE) and the Compass Corrosion Guides.
Hose Master understands the importance of the three variables discussed above. We take pride in being knowledgeable and responsive to our customer’s needs, so we are glad to make product recommendations that best satisfy the above requirements. Our trained customer service associates and experienced engineers strive to make sure customers receive the product that is perfectly matched to their needs. The company encourages those customers to use Hose Master’s highly trained employees in Customer Service, Field Sales Support and Engineering to assist in designing hose assemblies to meet specific application and delivery systems.
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