Subject: The ten most important features you can specify in a mechanical seal design. 14-11

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A mechanical seal should operate leak free until the wearable face (normally carbon) is worn smooth. Ninety percent of mechanical seals leak prematurely. Surprisingly the seals fail for only two reasons:

If these are the only reasons why seals fail prematurely, and they are, then any sensible mechanical seal design would address these two problems. Here are the ten most important features you can specify in any mechanical seal design

1. Deal only with known seal materials. Be sure these materials are chemically compatible with what you are sealing and any cleaners or solvents that might be flushed through the lines.

2. Choose seal designs with built in slurry or anti-clogging features:

3. Avoid spring loaded elastomers or rubber parts

4. Specify seal designs that are hydraulically balanced.

5. Specify stationary seal designs where the seal springs do not rotate with the shaft

6. Cartridge designs simplify the installation process and make the important impeller adjustment of semi-open impeller pumps possible.

7. Be sure the lapped seal faces say flat. If they are not flat to within three helium light bands the lapped seal faces will probably leak

8. Use the correct environmental control to stop the product you are sealing from changing state and opening the lapped seal faces.

9. Use an API type gland if you have the option

10. Stay with non-fretting designs

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