Pentair 3" x 2 3/8" FNS Polyethylene Washer

The Pentair 3" x 2 3/8" FNS Polyethylene Washer (part number 195004Z or 195004) is a specialized structural spacer and sealing cushion designed for the internal plumbing manifold assemblies of Pentair FNS, FNS Plus, and select vertical grid Diatomaceous Earth (D.E.) pool and spa filtration systems (including models FNS 24, FNS 36, FNS 48, and FNS 60). Stamped from a high-density, marine-grade polyethylene thermoplastic, this flat circular spacer measures approximately 3 inches in outer diameter, features a 2-3/8 inch inner clearance hole, and carries a low-profile thickness of 1/4 inch. Its primary operational role is to isolate critical mechanical stress points within the pressurized tank core—most notably where the internal standpipe, manual air relief tubes, or lower bulkhead fittings clamp together against the composite tank shell. By acting as a durable, low-friction buffer zone, it evenly distributes the concentrated installation torque from heavy retaining nuts, ensuring that the heavy hydraulic flow forces and standard operational pressures up to 50 PSI do not cause structural binding, localized stress cracking, or thread distortion at the connection interfaces. Engineered to remain permanently submerged in chemically treated pool water, it completely resists degradation from concentrated chlorine, bromine, salt-chlorine generator outputs, and seasonal acid washes without swelling or turning brittle. Due to its lightweight, low-profile plastic ring geometry, this individual polyethylene washer carries a nominal product and shipping weight of approximately 0.03 to 0.05 pounds (about 0.48 to 0.80 ounces).