Pentair 19" x 4" Posi-Lok™ Ring

The Pentair 19" x 4" Posi-Lok™ Ring (OEM Part #27001-0054S / #27001-0054Z) is a critical structural safety and containment component engineered specifically for Pentair Sta-Rite System 2 pool and spa filtration systems. This heavy-duty collar locks the upper and lower halves of the filter pressure vessel together on System 2 Modular Media (PLM Series, models PLM100 through PLM300) and System 2 Modular D.E. filters (PLD and PLDE Series, models PLD50 through PLDE70).

Functional Overview

Molded from a thick, high-impact, UV-stabilized composite polymer, this ring features an engineered internal buttress thread design. Instead of using a metallic split-nut clamp secured by bolts, the Posi-Lok ring utilizes a continuous hand-tightened spin profile to compress the main tank shell cord-ring O-ring. Its primary operational role is to safely absorb the severe internal hydraulic pressures generated during pump filtration cycles, preventing catastrophic separation of the tank domes. To ensure proper technician engagement and prevent over-tightening or pressure failure, the outer perimeter of the rim features prominent, molded-in "LOCKED" and "REMOVE" directional indicators that align directly with the tank's spring-loaded safety latch hardware.

Weight and Dimensions Profile

• Actual Product Weight: Approximately 2.35 to 2.50 pounds.

• Physical Dimensions: The ring features an inner diameter of 15.5 inches and an outer edge boundary of 17.5 inches. However, due to its specialized geometric flange construction and overall height, its broad physical footprint spans roughly 23.75" in length by 21.25" in width by 5.5" in height.

• Packaged Shipping Weight: Typically scales at 4.0 to 5.0 pounds because its large, rigid ring geometry requires an oversized, flat cardboard container heavily insulated with void-fill packaging to protect the high-stress composite threads from being dented, flattened, or fractured during transit.