How a Lantern Ring Helps Ensure Stuffing Box Reliability



Stuffing box reliability is critical to the condition and performance of the whole fluid sealing program. And ensuring stuffing box reliability and controlling the pump environment can mitigate many reliability issues. But how do we accomplish this? The answer lies in something small, unassuming, yet crucial — a lantern ring. First, let’s discuss stuffing boxes.

What Is a Stuffing Box?

A stuffing box of a pump houses a gland that compresses the packing used to seal the pumped fluid. It prevents leakage along the shaft that passes through a hole in the pump.

stuffing box lantern ring reliability
All centrifugal pumps have a stuffing box or seal chamber.
This small — yet important — space is where most of the activity happens within a pump, including:
  • Fluid containment
  • Shaft movement
  • Shaft sealing
  • Motor connection
  • Potential contamination points (aka lubrication into the process fluid/process fluid into the lubrication)

However, because of the critical role it plays in pump system reliability, the stuffing box is also ripe with potential failure possibilities.

What Is Stuffing Box Reliability?

When it comes to overall system reliability, the better the performance of a fluid sealing program, the better the condition of the internal pump components, including the stuffing box.
Additionally, proper packing installation to prevent excessive leakage, shaft stabilization to prolong shaft/sleeve and packing life, and thorough equipment inspections help improve stuffing box reliability.

So, how do we protect this notorious leakage path and increase stuffing box reliability and, ultimately, pump system reliability?

According to a recent article on PumpsandSystems.com, the answer lies in lantern rings.

“Lantern rings protect the stuffing box and the installed packing by providing an access point for flush water.” the article said. “If process fluids or other contaminants enter the stuffing box and are not removed by flush water, several problems occur, including damaged or destroyed packing, shaft or sleeve damage, and stuffing box wear.”

What Is a Lantern Ring?

Perforated lantern rings are typically found at the center of every packing set in a centrifugal pump. And while they are simple components, big problems can occur within the stuffing box should something wrong when selecting, installing or operating them.

packing with rings lantern ring stuffing box reliability
Example of a lantern ring and its location in a packing set

According to the Pumps & Systems article, “a lantern ring is placed between packing rings in each packing set and extends the life of the packing, stuffing box and shaft. Ultimately, lantern rings increase the life span of the pump system.”

Additionally, lantern rings serve three primary purposes: protection, cooling, and lubrication.

“They protect the stuffing box and the installed packing by providing an access point for flush water.” the article said. “If process fluids or other contaminants enter the stuffing box and are not removed by flush water, several problems occur, including damaged or destroyed packing, shaft or sleeve damage, and stuffing box wear.”

A lantern ring also gives the stuffing box an outlet to assist with cooling by allowing the system to avoid being completely closed off and assists in mitigating overheating.

And lastly, lantern rings play a crucial role in lubrication.

“Packing causes friction along the shaft and stuffing box walls or casing,” the article explains. “Fluid entering through the lantern ring lubricates the packing. The liquid reduces friction, limits the wear of the machine’s parts and decreases heat within the system.”

The Critical Role a Lantern Ring Plays in Stuffing Box Reliability

While packing selection and proper installation are key, failure is imminent if the lantern ring is installed incorrectly or blocked.

“Ignoring the importance of lantern rings can be easy,” Kaufman and Tanner wrote. “They are small and may seem to be an inconsequential, consumable component. However, end users who regularly examine lantern rings for correct type, installation and clogging see longer packing life, fewer shutdowns for packing replacement, and less shaft wear and damage.”

In other words, correct lantern ring selection, operation, and maintenance helps ensure stuffing box reliability.

Read the full article on PumpsandSystems.com to learn more about the crucial role lantern rings play in stuffing box reliability and overall pump system reliability.

About the Author
Anna Claire Howard is a contributing writer and editor for Sealing Equipment Products Co. Inc. (SEPCO) and has been since Spring 2019. She is a full-time freelancer and stay-at-home-mom. Before those two big life changes, she was the content marketing specialist for Fluke Accelix; assistant editor for Grand View Outdoors, publisher of Bowhunting World, Predator Xtreme, Whitetail Journal, Tactical Retailer, and Shooting Sports Retailer; managing editor for Media Solutions, Inc., publisher of Gear Solutions, Wind Systems, and Thermal Processing magazines; assistant editor for MSI; and the editorial intern for B.A.S.S., LLC, publisher of Bassmaster Magazine and Bassmaster.com. In these B2B/B2C roles, Anna Claire developed an appreciation for the industrial sector, as well as the operators and technicians who make up the workforce. You can find her on LinkedIn at bit.ly/ACHowardLI.

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