GS (General Service) Metal Bellows

Metal Bellows seals can seal with Flexible Graphite instead of a rubber boot or o-ring Elastomers allowing it to be used in higher temperature applications No Springs to clog. Metal Bellows seals are a very effective method of maintaining seal face pressure on the seal face.

Metal Bellows seals that do use o-rings only require one static o-ring to seal off any leakage along the shaft in Chemical Service this o-ring can be Aflas, EPDM, Nitrle, Viton, Encapsolated PTFE, Ameri-rez, or PTFE Because the o-ring is static it will not wear on the shaft.

When installed correctly metal bellows seals will provide exceptionally long service. Metal bellows seals are and excellent solution on chemical applications where Kalrez, Chemrez,Viton, FKM, Buna, Aflas or EPDM are not compatible.

For many years an inexpensive form of metal bellows seals have been used very successfully in the waste water / sewage industry and in the agricultural fields pumping irrigation water. These seals were generally made of a formed bellows rather than a welded bellows. Welded bellows seals are much stronger and have superior flex and recovery characteristics which are more ideal to holding seal faces together but cost more to manufacture. Welded metal bellows seals are less prone to metal fatigue and are available in single and double ply.

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ASP Type 9 Mechanical Seal

Mechanical seals often need to be used in chemical applications. When confronted with some harsh chemicals, mechanical seals containing elastomers made of Viton, Kalrez or Chemrez can't hold up. Because PTFE (polytetrafluoroethylene)or as most people know it Teflon ® , has a 0-14 ph range it usually will hold up.

Like most materials every choice has an up and a down side. PTFE will handle most chemical applications, chemical attack is no longer an issue. On the down side PTFE wedges can cause fretting of your sleeve or shaft if you have not hard surfaced your shaft or sleeve (plasma coating).

The stationary element of your seal will require a PTFE gasket. It's not much good to have a PTFE on the rotary and then use an elastomer on the seat. We have seen it done, and because it is a static application some have gotten away with it, but it is not recommended. Most commonly the seat will be a L-shaped or Clamped mount style to allow space for a PTFE gasket to be used as the secondary sealing element.

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