Cartridge Seals: The Modern Alternative to Conventional Seals

Author: Vern Frahm | December 22, 2014 | Category: Mechanical Seals

Mechanical seals (conventional and cartridge) offer an alternative to packing. Over the years, advancements made to face materials and elastomer selections have played an important role in mechanical seals becoming a more superior option. 

Conventional seals are not without their challenges, however. Conventional seals require the operator to set and align the seal on the shaft or sleeve of the pump, a task that is difficult to say the least. This can increase margin for error resulting in premature failure. With reducing maintenance costs and downtime becoming highly valued assets in manufacturing, cartridge seals are quickly becoming the seal of choice. Continue reading to learn about cartridge seals, installation, and some things to remember.  


Untrained operators and installation errors are some of the reasons seals fail prematurely. To help operators overcome the fitting and installation problems associated with conventional seals, cartridge seals were developed. Cartridge seals are self-contained units consisting of a shaft sleeve, seal, and gland plate. The design of the cartridge seal works to eliminate common causes of seal failure from installation errors, and because the seal is presented on its own shaft sleeve, any damage that might be caused by a conventional seal to the pump unit is eliminated.


It's pretty simple actually: Slide the cartridge seal over the shaft as the pump is being built, align the gland ports, finish building the pump, evenly tighten the gland, tighten the collar set screws, and remove the spacers. Easy, right? The cartridge unit is fitted onto the pump shaft as a whole, pre-built assembly, which requires no further fitting adjustments (when compared to conventional seal installation procedures). The most common mistake we see is mechanics attaching the cartridge seal to the seal chamber BEFORE installing it on the pump - wrong! 

Since the cartridge seal does not require the usual setting measurements and adjustments, maintenance costs are lowered and seal installation errors are minimized leading to more optimal seal life. 


When using cartridge seals, make sure the unit is in good operating condition to minimize any future problems, such as a leak after the seal installation. Check the following:

  • Are the bearings within tolerance?
  • Is the shaft straight?
  • Is the impeller in balance?
  • Are there any effects of cavitation present?

And, most importantly, cartridge seals offer a level of standardization no matter what OEM machine is being sealed. When switching from conventional to cartridge, a drop off in seal performance should NOT be expected. 

If you have questions about mechanical seals, contact us today! Your message will be routed to the appropriate Engineer for review. We're happy to provide assistance to businesses throughout Wisconsin and upper Michigan. 

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Vern Frahm

Vern Frahm

Vern was an integral part of the Service and Repair Group at Crane Engineering. With over 40 years logged at Crane, he was a sought after trainer for our customers. As of 2015, Vern has retired. :)

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