U.S. Seal PS-3865R Premium Shaft Seal Assembly

The U.S. Seal PS-3865R is a heavy-duty mechanical shaft seal designed for use in a wide range of pool and spa pumps — including many models from Pentair, Waterway, Sta‑Rite, AquaFlo/Gecko Aqua-Flo, and several hot-tub/wellness-pump brands. It’s built for durability and chemical resistance, making it well-suited for pools using salt systems or ozone/bromine generators.

Key Features

• Premium shaft seal assembly — heavy-duty construction for longer life under salt, ozone, or standard chlorine water conditions.
• 5/8″ impeller-shaft fit — standard sizing for many pool/spa pump shafts.
• Viton- and ceramic-seat components — improve resistance to heat, chemicals, and wear compared with basic seals.
• Carbon-graphite primary ring with stainless-steel hardware for reliable sealing under pressure.
• Ideal for salt water or ozone/bromine sanitation systems — better chemical resistance than standard rubber/carbon seals.
• Broad compatibility — fits many popular pump makes and models, reducing need for multiple special-order parts.

Specifications

• Manufacturer: U.S. Seal
• Part Number: PS-3865R
• Shaft Size: 5/8″ (impeller shaft diameter)
• Seal Material: Viton elastomer, carbon-graphite primary ring, ceramic sealing seat, stainless-steel hardware
• Type: Reverse-style mechanical shaft seal (wet-end pump seal)
• Application: Pool and spa pumps — including salt, ozone, or bromine systems; suitable for both residential and spa-grade pumps

When to Use / Replace

Install the PS-3865R whenever you rebuild or service your pool/spa pump — especially if you use salt, ozone, or bromine sanitation. Also replace it if you notice water leaking from the pump wet end, reduced pressure under load, or any sign of seal wear or shaft corrosion. Because it’s a critical watertight seal between the pump housing and motor shaft, replacing it proactively can prevent damage to the motor and avoid costly repairs.

Installation Tips

• When replacing, disassemble the pump wet end, remove the old seal, and thoroughly clean the seal cavity and shaft before installing the new PS-3865R.
• Use a pool-safe water-based lubricant (e.g. P-80-style seal lube) to help seat the ceramic face without damaging sealing surfaces. Avoid petroleum-based or silicone greases that can damage Viton or ceramic components.
• Ensure the shaft and seal seat are free of nicks, corrosion or debris — even small imperfections can cause leaks or premature failure.
• After reassembly, run the pump and check for leaks around the wet end before putting the pump into full service. Retighten and re-inspect after the first hour of operation under load.