By Todd McMonigle

When repairing a pump that currently has a component mechanical seal* (or packing**), it is worth considering upgrading to a cartridge mechanical seal design. Component seals include multiple parts (rotor, rotor face, stationary face, springs, O-rings, gaskets, and seal gland) that require considerable handling and also require more care and skill during installation. For this reason you can incur potentially more assembly errors, including wrong spring setting—and therefore improperly loaded faces, dirt or grease contamination on sealing faces, damage to sealing components from mishandling, and sometimes just plain forgetting to use a needed part (like omitting a gland gasket…been there!). Any of these will result in immediate or early failure of the mechanical seal.  (Note: It is always a good idea to air test—at 25 psig—a rebuilt pump on the bench prior to putting it back into service).

On the other hand, a cartridge seal is a FULLY pre-assembled mechanical seal. It includes all of the parts mentioned above in the component seal (plus a seal sleeve), but in a prepackaged, preset, factory assembled and factory-TESTED product. All of the potential issues mentioned above with a component seal are eliminated with a cartridge seal. As with any mechanical seal installation, however, careful attention must be paid to proper installation practices and techniques—regardless of whether it’s a component or cartridge seal. Also, cartridge mechanical seals can sometimes require additional seal chamber clearance or axial space requirements; that is another reason to consider upgrading during a pump rebuild, when you have the tools and machining capabilities readily at hand (if needed).


  • Installation time is reduced considerably compared to a component seal installation
  • Seals come with installation grease, tools, a detailed drawing, and sometimes extra set screws and O-ring materials
  • Multiple features, seal designs, materials, single and double configurations, and internal interchangeability
  • Most manufacturers offer “half-price” repair programs or exchanges, often regardless of the poor condition of the seal
  • Manufacturers also provide further deep discounts on new seals when converting a competitor’s cartridge seal

For more information about component and cartridge mechanical seals, contact an OTP Industrial Solutions expert. Our team takes pride in the technical knowledge and broad product support we provide to help our customers build and maintain top performing industrial systems.

*Mechanical Seal – precision sealing device used to virtually eliminate process fluid leakage (as
low as 3 drops/day) along the pump shaft or other process equipment shaft.

**Packing – early method of sealing the pump shaft by means of compressing or squeezing
together multiple flexible rings or “ropes” to create a seal. Generally leakage rates are required to
be a minimum of 60 drops/minute and are often times much greater. Packing is still used today
quite extensively.


COLUMBUS, OHIO—OTP Industrial Solutions has merged with and hired the associates of R.J. Knoepfler Company, a finishing and fluid handling distributor based in Cincinnati, Ohio. As a result of the merger, OTP now offers R.J. Knoepfler customers an extensive finishing and fluid handling inventory, as well as industrial solutions and support for bearings, fluid power, pumps, mechanical and electrical products. R.J. Knoepfler Company will take on the name OTP Industrial Solutions as their employees join nearby OTP branch locations.

OTP Industrial Solutions welcomes R.J. Knoepfler Company’s rich history, expertise and product solutions. Founded in 1952 by Bob Knoepfler, R.J. Knoepfler Company began as a finishing distributor selling to manufacturing companies and wood finishing businesses in Ohio and Indiana. Bob served as the company’s president for 21 years until his passing in 1974. At that time his wife Dorothy Knoepfler and Ed Burns took over, expanding the company’s sales coverage into Kentucky, Tennessee and West Virginia. In 2005 Jeff Burns became president and added additional finishing and fluid handling products to the company’s list of manufacturers that it represented and technically supported, along with its complete turnkey systems and solutions.

For more information about the R.J. Knoepfler Company merger, please contact OTP Industrial Solutions.

About OTP Industrial Solutions

OTP Industrial Solutions is one of the largest industrial distributors and service providers in the United States. Established in 1963, the corporation recently celebrated its 50th anniversary. Its divisions include OTP Industrial Solutions, a provider of expert solutions for industrial motion control, fluid power, power transmission and pumping systems, and Air Technologies®, a compressed air system equipment and service provider and the largest distributor of Atlas Copco compressed air equipment in North America. Ohio Transmission Corporation maintains locations throughout the Midwest and in Texas. Ohio Transmission Corporation’s more than 500 associates share its founding vision of delivering excellent value through work with integrity. For more information, please visit and