AquaMatic K521-109 1" Retaining Ring & Nut Assembly - EP (Pair)

The AquaMatic K521-109 Retaining Ring & Nut Assembly is a factory-original, commercial-grade hardware kit designed to securely mount pipe end adapters to AquaMatic K521 Series 1-inch composite body diaphragm valves.

This standard EP (EPDM) configuration contains a complete pair of nuts, split retaining rings, and high-quality EPDM face O-rings. It provides the essential mechanical clamping force and leak-tight seal required to connect pipe adapters—such as the K521-PC 1" Solvent Weld Adapters (1070226)—directly to the valve body ports. Utilizing EPDM elastomers makes this kit the perfect choice for everyday commercial and industrial water treatment applications, offering excellent resistance to ozone, sunlight, weathering, and mild alkaline or acidic solutions.

Parts Included List

One kit contains enough hardware to complete both the inlet and outlet connections for a single 1" K521 series valve. The assembly includes:

• 2 x Heavy-Duty Union Retaining Nuts: Threaded collars that draw the pipe adapter tightly against the valve port face.

• 2 x Split Retaining Rings: Interlocking rings that snap firmly into the exterior grooves of the pipe adapters to distribute mechanical clamping pressure evenly.

• 2 x EP (EPDM) Face O-Rings: Durable, resilient elastomeric seals that prevent fluid bypassing at the connection interface.

Key Features & Benefits

• Resilient EPDM Sealing: Features authentic EP (EPDM) O-rings that excel in hot and cold water applications, offering superb resistance to aging, ozone, and dilute chemicals.

• Convenient Union Coupling: Creates a reliable, quick-disconnect union joint, allowing the valve to be rapidly removed from the pipework for bench servicing or routine internal maintenance without cutting into the lines.

• Perfect 1" System Fit: Explicitly engineered by AqMatic / Pentair to match the 1-inch K521 composite valve body thread and flange profiles flawlessly.

• Cost-Effective Durability: Constructed from rugged, industrial-grade materials designed to provide long-lasting joint security in standard commercial water softener and filter setups.

Technical Specifications

Applications & Systems

The K521-109 EP hardware kit is the standard go-to assembly for conventional commercial and industrial water management, including:

• Commercial water softeners and multimedia sand or carbon filtration backwash loops.

• Pre-treatment filtration arrays for Reverse Osmosis (RO) systems.

• Municipal and institutional water conditioning setups.

Installation Tip: Always remember to slide the union retaining nut and the split ring onto your pipe adapter before completing any permanent solvent welding or pipe jointing. Ensure the EPDM O-ring is seated completely flat in the face groove without twists before hand-tightening the nut onto the valve body. Hand-tighten firmly—the high-precision engineered threads are designed to seal efficiently without the need for high mechanical torque or heavy pipe wrenches.