Cartridge vs Component Mechanical Seals: Which Do You Need?

Cartridge vs Component Mechanical Seals: Which Do You Need?

What is a component mechanical seal?

The original style of mechanical seal, and still widely used. The parts arrive loose: the rotating unit, the stationary seat, the secondary seals and the gland parts, and they are assembled onto the shaft one by one during installation. The person installing it sets the load on the seal faces by measuring the working length on the shaft. Done well, a component seal gives excellent service. It simply puts more of the result in the installer's hands.

What is a cartridge mechanical seal?

The complete seal built at the factory onto its own sleeve, with its own gland: faces, springs, secondary seals and setting clips, all in one unit. Installation is slide it onto the shaft, bolt the gland to the pump, set the drive, and remove the clips. The critical setting of the faces was done on a bench, not on your shaft, so far less depends on measuring on the day.

Why does installation decide so much of a seal's life?

A mechanical seal lives or dies by the condition of its two faces and the load pressing them together. Too much load and the faces run hot and wear; too little and the seal weeps. With a component seal that load is set by hand on site, and published reliability literature puts a large share of premature component seal failures down to installation. A cartridge seal removes most of that risk because the setting is built into the unit.

When does a component seal still make sense?

When the equipment was designed around one and a like-for-like part is what you need. When the budget is tight, since a component set costs less to buy than the equivalent cartridge. When your own people set seals regularly and do it well. And when only one part has failed, since the individual pieces can be replaced on their own.

When is a cartridge seal worth it?

When downtime costs more than the seal. When the pump is critical, awkward to work on, or worked on by different people each time, because a cartridge change is the same job every time: old unit off, new unit on. And on hazardous duties, because most double seals are supplied in cartridge form anyway, which is where the single versus double question meets this one.

Can you change from component to cartridge?

Usually, yes. On most standard centrifugal pumps a cartridge goes into the existing seal chamber with no machining, provided there is room on the shaft outside the gland. To confirm it we need the shaft size, the seal chamber dimensions, and the duty the pump is on. Many plants move to cartridge one pump at a time, starting with the worst offender.

How do we choose for your pump?

Send us the pump type, shaft size, seal chamber dimensions, and the fluid with its temperature and pressure at the seal. We select and supply both component and cartridge mechanical seals, and we will tell you plainly which one suits your pump and the way you work, and why.