How Hydraulic Fluids Effect Your Seal Compatibility

Colonial Seal had a situation with a customer a few years back regarding premature hydraulic seal failure. At the time we thought they had been sent either the wrong seal or the incorrect seal material. We began to analyze the issue and quickly realized that the customer had just switched to a fire-resistant hydraulic fluid so that they could create a safer working environment.  No research was done by the customer as to how this change would impact his machinery and its components, including the seal.  

The result was that the EPDM seal was not compatible with the new fluid, and it was being absorbed at an accelerated rate, causing the seal lip to “swell.”  This swelling caused increased wear on the seal, resulting in decreased seal life, along with unacceptable leakage.  If the decision is made to change the hydraulic fluid currently being used in your assembly, consideration should be taken when it comes to “compatibility” and how this change will react with the internal components of your machinery.  

You want to take proper measures so that your seal lip material is compatible with the chosen application media.  Once you understand how your seal material will interact with various fluids, you will be able to find the right match.

One way Colonial Seal helps their customers find the perfect solution is by implementing five specific guidelines called S.T.A.M.P.

S.T.A.M.P.

Speed - What is the speed under which the seal will be required to perform?  This speed could be represented as RPM (Rotations Per Minute), FPM (Feet Per Minute), or MPS (Meters Per Second).

Temperature - What are the minimum and maximum temperatures the seal will       be exposed to in the application?  This could be given by degrees in either Celsius or Fahrenheit.

Application - Where is the seal being used?  What is the seal function?  This refers to the equipment in which the seal is being installed as well as what the function is of the seal in the application.

Medium - What is the media?  This is referring to the lubricant or viscous

material that is to be sealed or excluded.  Are there compatibility considerations?  Examples of possible media are grease, oil, hydraulic fluid, water, etc.

Pressure - What are the minimum and maximum pressures the seal will be exposed to in the application or environment?  This could be designated in either PSI (Pounds per square inch) or BARS (1 BAR is equal to roughly 14.5 psi).

After you have determined the S.T.A.M.P. criteria, the next step is determining the dimensions for your seal.  These values could be given in two different methods; either the actual SEAL dimensions OR the STEEL dimensions, i.e. the shaft, bore and groove dimensions.  

The vast majority of seal suppliers prefer that the dimensions provided are the steel dimensions, since it is sometimes difficult to measure the actual seal inner diameter. For replacement seals, the steel dimensions are usually found on the rubber outer case portion of the seal. 

With the S.T.A.M.P. guideline, feel free to breathe a sigh of relief the next time you are assigned the task of finding a particular sealing solution.  Whether the seal is an industry standard part or a custom design for your unique application, rest assured that you will be able to provide the proper solution thanks to S.T.A.M.P.!  For any additional information or to request a quote please visit our website at www.colonialseal.com/contactus.html.