Cartridge Mechanical Seals (short CMS) are seals that are actually closed mechanical seals (short MS). They are composed from housing, shaft and a MC. A lot of different types and dimensions of CMS exist. Each company has its own types of CMS. In short, there are countless of types of CMS and MS. The main advantage of CMS is easy assembly and dissasembly. The negative side is mainly cost. They are very expensive, as we all know.
Due to its cost, it makes sence to refurbish them. Unless, of course, the are too ruined. Sometimes there is only housing that can be used in refurbished CMS. Everything else has to be produced, including shaft and belonging MS.
Aniway, in general, most of the CMS parts can be used in refurbished CMS. In most cases, only MS has to be refurbished or a new one has to be installed. But, of course, the first step in refurbishment is dissasembling the CMS and cleaning them. This can be very unpleasant.
A few weeks ago we received a middle sized CMS for which we immediately knew it was used in sewage. The smell was unbearable. In spite of temperatures below zero we openned doors and windows.
We rather endured cold than smell. Besides that, refurbishment was standard. After unpleasant beginning it turned out that only MS needs more attention. It was a single seal CMS. In fact, sliding surfaces of stationary seat and rotating seal were completely ruined. The actual sealing was performed by housing in which sliding surfaces were and dirt from sewage. We renovated both housings and embeded Wolfram-Carbide sliding rings in them. Wolfram-Carbide is the only material that withstands punishment from sewage. While assembling the CMS we used VITON secondary seals.