Gallagher Fluid Seals is a Parker Distributor is proud to be proud to be one of the few premier distributors to qualify as a “Parker Seal Technology Center (STC)”.

What does a good seal engineering drawing look like?

You just spent 6 months testing, stretching, aging and exposing your new seal design to 12 different chemicals. Finally, you are done. So what does a good technical drawing for a seal include? For most companies, the drawing is simple. For an O-ring, usually it's simply a generic circle which shows an ID and width with some sort of material called out.

But now, fast forward 25 years. Someone references the drawing - how do they know the criteria utilized to select the seal?

For example, a customer was having issues on their engine sensor seal: “Was the original seal specified to be compatible with biodiesel?” The engineer consulted their drawing, but besides the generic circle, it lacked any information on what material compatibility was considered when the seal material was selected. The ASTM description on the drawing did not include a reference to or indicate compatibility with biodiesel.

Be specific with materials on seal drawings

Over time, the operating parameters of a system or product can change, so it is important to know what parameters were used for the original seal selection. The goal of the drawing is to assure that the engineers and procurement team understand what performance is required from the seal and why the specific elastomer was chosen.

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So how do you make your drawing more valuable to your company?

  1. Define and list on your drawing all the operating conditions you anticipate the seal will see, such as temperature, pressure, and any other application specific operating conditions.
  2. Prepare a list of fluids as well as the concentrations of each fluid that your seal will be exposed to. Add these on your drawing. In addition, make sure you consider fluids that could come into contact with the seal indirectly through failure of other systems that are part of the product or even by cleaning the product.
  3. List the selected compound and manufacturer on the drawing. Clearly define what testing the compound was put through or what testing is required for approval.
  4. If you select a compound that was resistant to compression set, high temperatures or low temperatures, as well as explosive decompression, this should be clearly stated on the drawing.
  5. List clearly the industry standards the seal is required to meet, such as UL, FDA or NSF.

List fluid compatibility requirements

Time and time again, Gallagher sees seal quality and performance failures when a new supplier is selected and the real requirements for the seal were either forgotten or not clearly defined. Clearly defining these parameters and making them transparent will allow your purchasing and technical team to understand, select, and evaluate the correct compound that meets your products sealing requirements.

Once you select a compound for your specific application, it is important to test and validate that the compound chosen is compatible with the fluids you are using. If you choose to list an alternate compound on your drawing, that compound must also be tested and validated for compatibility.

Remember when developing drawings standards, assure yourself that if someone consults a drawing that is 2 years old, 5 years old or even 20 years old, they will know the intent of the original seal design.

For more information about custom sealing solutions or information about Parker seals, please contact Gallagher's engineering department.

Article re-posted with permission from Parker Hannifin Sealing & Shielding Team.

Original content can be found on Parker’s Website and was written by Fred Fisher, technical sales engineer of the Engineered Materials Group.