Ensuring stuffing box reliability and controlling the environment mitigate many issues in the ‘space’ where it happens.

PTFE Lantern rings serve three purposes: protection, cooling and lubrication. They
protect the stuffing box and the installed packing by providing an access point
for flush water. 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
• stuffing box wear

A lantern ring also gives the stuffing box an outlet to assist with cooling. It allows the system to avoid being completely closed off and assists in mitigating overheating. The final lantern ring purpose is lubrication. Compression packing causes friction along the shaft and stuffing box walls or casing.
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.

Selecting the correct material for the application is critical. Lantern ring selection should be given equal consideration because they are equally as important as packing.  PTFE and PEEK, general material for Lantern Ring.

Most packing sets have five packing rings. The lantern ring can be inserted after the second or third packing ring is installed. This all depends on where the flush port of the stuffing box is located. To ensure that the lantern ring is installed correctly, insert a small object through the flush port and feel the lantern ring.

Once this is done and all the packing rings and packing follower are installed, end users should install the proper flush setup and start flushing the stuffing box. For many reasons, starting the flush before operating the pump is important. One reason is to ensure that flush water is moving through the lantern ring and into the stuffing box correctly.

Care must be taken to ensure the lantern ring’s fit around the shaft is correct. Most lantern rings have a larger fit on the inside diameter and a tighter fit on the outside diameter, so frictional heat is not an issue.