Compression Packing vs. Two-Piece Fully Split Cartridge Mechanical Seal: Which is More Effective?

packing vs split seal

Compression packing is used to control water leakage along a pump shaft and to prevent air from entering the process. A packed pump requires substantial power to operate, and every additional ring of packing increases the plant’s energy need. Packed pumps also create hefty demands on water resources to combat the heat generated by friction between the packing and pump shaft. From an energy usage standpoint, a packed pump is a money pit.

Choosing just the right compression packing to seal a pump – while minimizing temperature variances and shaft abrasion – is a tricky process at best. Once a compression packing has been chosen, you still have to contend with putting it on the pump.

Installing or replacing compression packing is at least a six step process:

  1. Amassing the proper tools
  2. Shutting down the pump
  3. Pulling out the old packing
  4. Checking the wear of the pump shaft and stuffing box (and repairing any damage before proceeding)
  5. Installing the new packing
  6. Restarting the pump.

And don’t forget those tools. They will include a knife to cut the packing, packing hooks to remove the old packing, a flashlight and mirror to assist in finding the lantern ring, items like wood setting blocks or sleeves to seat the packing and packing lubricant to treat the packing before installation. But your work isn’t done yet. Packing demands on-going maintenance to ensure it works properly. And maintenance requires manpower, which comes with a significant price tag.

Packing is designed to degrade with normal use. Compression packing can also fail unexpectedly; notably in cases where the incorrect packing was chosen, the packing was overtightened, pump shaft damage was not repaired before installation of new material, or abrasive materials were not effectively flushed. And when the packing fails, the process of choosing and installing the correct material begins all over again!

Compression packing may initially appear inexpensive but when all the associated costs are tallied, packing is considerably more expensive over time than the installation and operation of a mechanical seal.

Flexaseal’s Style 85 and 85M Fully Split Cartridge Mechanical Seals address all these concerns associated with compression packing.

  • Easy installation: no measurements. No special installation tools. Simply bolt the two seal halves around the pump shaft by tightening the shoulder bolts, secure cartridge seal to the pump by tightening gland bolts, secure shaft sleeve to the pump shaft by tightening set screws and then remove setting clips.
  • Hydraulically balanced seal faces lower heat generation, minimizing the need for excessive water cooling and allowing for a wider range of operating pressures. Balanced seals utilize less than ¼ the resources of standard compression packing.
  • The stationary design of the Style 85/85M ensures optimum seal face tracking and alignment. You do not need to constantly adjust the seal due to wear.
  • The large diameter cross-section dynamic O-ring slides on a smooth, clean, stationary seal ring surface eliminating pump shaft damage due to abrasion and fretting.

In addition, our Style 85 line greatly minimizes installation guesswork.

  • Only two enclosed seal halves are handled. No more juggling multiple items during installation.
  • The faces, O-rings, and springs are all encased in the cartridge, protecting them from clogging and corrosion.
  • The Style 85 fully split cartridge mechanical seal is completely assembled and pressure-tested at our factory, ensuring sealing integrity and providing a high installation success rate.

 

Challenge: Picking the Right Mechanical Seal for Mixers and Agitators

split cartridge mechanical seal

Every mixer and agitator model is distinctive, engineered for a specific use and, in some instances, can appear to be similar to a pump application. Consequently, conventional pump seals such as single or double seal assemblies, lip seals, or packing material are often used to seal mixers and agitators. However, these pieces of equipment are known for having much larger radial shaft run out than a typical pump which can cause pump seals to quickly fail. For long-term sealing success, it is extremely important to utilize a seal specifically designed specifically as a mechanical seal for mixers and agitators.

 

Today’s Common Mixer Options

  • Sanitary mixers are designed for applications like sanitary agitation, biopharma, food, beverage, and biofuels. These applications have demanding quality standards, as well as a need for efficient, consistent mixing.
  • Bottom entry mixers and agitators are used for processes such as storage tank mixing, fermentations, and bioreactors. These applications often encounter accumulating solids around the seal.
  • Top entry mixers are common in chemical processing, food industries, and industrial waste water. These powerful mixing systems still command the majority of the mixer market.
  • Side entry mixers are standard equipment for most storage tank mixing, fuel oil blending, and wastewater agitation. Excessive run out is the number one challenge when sealing side entry mixers.

 

Flexaseal’s Style 85M Fully Split Cartridge Mechanical Seal addresses the sealing concerns in mixer and agitator usage.

    • Large radial clearance allows for shaft movement without damage to the seal’s components. This clearance effectively addresses the matter of run out – the main concern when sealing mixers and agitators.
    • The two-piece fully split cartridge mechanical seal design is the fastest, easiest, and simplest to install. No measurements, shims, or special tools needed. And more importantly in the case of side or bottom entry mixers: no emptying the tank to install or adjust the seal!
    • Which means this is the only split cartridge mechanical seal installation in which the impeller can be adjusted without removing the seal. Simply reinstall the setting clips, release the set screws and adjust the impeller position then tighten the set screws and remove the clips.
    • The precision lapped seal faces are protected within the two cartridge halves. Dirt and grease cannot get impacted between the faces. In addition, the faces are hydraulically balanced, providing a wider range of operating pressures.
    • The stationary multi-spring design ensures that springs do not have to flex with every revolution. And since the springs are encased within the seal assembly, they do not come into contact with the sealed fluid which means no clogging or corrosion!
    • The seal’s O-ring is located outside the stuffing box, away from any damage caused by prior packing wear on the mixer’s shaft or sleeve.
    • And most importantly, the Style 85 Fully Split Cartridge Mechanical Seal is the only split cartridge mechanical seal design that arrives at your facility having been fully assembled and pressure tested at our facility, ensuring sealing integrity and providing the highest success rate for your installation.
      • To learn if Flexaseal’s Style 85M Fully Split Cartridge Mechanical Seal is the answer to your mixer and agitator needs,

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