To Replace a Hydraulic Hose, Remember: S.T.A.M.P.

Thursday, December 28, 2017 by ParkerStore Team

ParkerStore_To Replace A Hydraulic Hose, Remember STAMP So, you have a hydraulic hose that needs to be replaced. This is the perfect time to follow the acronym S.T.A.M.P. (for Size, Temperature, Application, Media, and Pressure) to be sure you install a new hose that’s properly matched to its job and will have the maximum lifecycle possible before it needs to be replaced again.

What size hose do I need?

The size determines the velocity of oil (or other media) running through the hose. Too fast may result in system damage, leaks, and inefficient operation. Too slow can cause low system pressure and poor performance. The inside diameter of a hose determines oil velocity: the smaller the I.D., the faster the velocity.

The correct hose size for a given application is a factor of flow in gallons per minute, velocity in feet per second, and I.D. (See Parker Hose Product Catalog 4400 Technical Section, pages E-3 and E-4, for a nomogram to help you choose the correct hose size.)

How does temperature affect the service life of this hose?

Two considerations are key to getting the maximum service life from the hose:

External Environment: This refers to the ambient temperature (outside the hose). The more extremely hot or cold the ambient temperature, the more durable the hose cover needs to be.
Conveyed Media: This refers to the temperature of the media flowing through the hose. One media type, such as air, may be rated at a different temperature than another, such as water—for the same hose.

Choose a hose with a working temperature equal to or greater than both fluid and ambient temperatures. See Parker Hose Product Catalog 4400 Technical Section, page E-5, and E-6 for a temperature chart to help you answer this question.

How does the hose application affect its dependability and performance?

Hydraulic hose is used in many different applications, each with its own set of requirements. These can be distilled down to four key elements:

Impulse and Duty Cycle: How frequently the hose is exposed to full pressure, as well as sudden pressure surges or spikes
Steel Wire Reinforcement Type: Spiral is better for high-impulse, high duty cycles than braided. But, braided is more flexible
Outer Hose Cover Strength: Categorized as tough or super tough. You may also need protective accessories such as hose guards or sleeves.
Bend Radius: If the hose is installed in a cramped space or is restricted in some way, you’ll need one that’s flexible, such as a Compact Spiral hose. (More on this in our blog post, Best Practices for Hose Installation and Routing Rules.)

See page E-10 to E-19 in Parker Hose Product Catalog 4400 Technical Section for a more in-depth look at applications, along with tools to help you address all factors—including installation tips, assembly methods, a thread guide, and metric conversions.

How does media affect hose requirements?

The media being conveyed must be compatible with the entire assembly: hose and fittings. If not, you risk contaminating and damaging your entire system, as a result of issues like hose cover blisters and erosion.

Our ParkerStore Identification Hose Failures video covers this topic in more detail. Also, refer to page E-20 in Parker Hose Product Catalog 4400 Technical Section for an overview of chemical resistance considerations.

How does pressure affect my hose selection?

The pressure isn’t just about relief valve limit or maximum working pressure. You also need to consider:

System Pressure: Is the system dynamic (fluctuating pressure, with potential for vibration, shock, and temperature changes) or static (mostly free of changes once it’s pressurized)?
Impulse Pressure: Pressure spikes or surges

In a dynamic system, the hose should have a working pressure equal to or greater than working and impulse pressures. Remember, this applies to the entire assembly, including hose ends. Refer to Parker Hose Product Catalog 4400 Technical Section, pages E-30 to E-38 for a more detailed look at pressure, including hose end connection ratings and a fitting size chart.