4 inch x 3 inch PCV DWV Reducing Coupling Plastic x Plastic

4” x 3” PVC DWV Reducing Coupling – Schedule 40 Solvent-Weld Transition Fitting

The 4" x 3" PVC DWV reducing coupling is a solvent-weld fitting designed for connecting two different nominal sizes of Schedule 40 DWV (Drainage, Waste, and Vent) pipe. This coupling provides a secure, code-compliant transition between 4-inch and 3-inch pipe systems in horizontal and vertical drainage applications.

Manufactured in accordance with ASTM D2665 and D3311 specifications, the fitting features socket ends for solvent-weld installation. It is constructed from rigid PVC Type I, Cell Class 12454 per ASTM D1784, and is suitable for gravity-fed DWV systems in residential, commercial, and institutional settings.

Technical Specifications

• Nominal Sizes: 4" x 3"
• Material: PVC Type I (Cell Class 12454, ASTM D1784)
• Fitting Type: Reducing Coupling
• Connection Ends: Slip x Slip (solvent weld)
• Applicable Standards: ASTM D2665, D3311; NSF-listed for DWV applications

Key Functional Characteristics

• ✅ Dimensional Accuracy – Molded to maintain tight tolerances for uniform solvent-weld bonding and consistent fit-up in field installations
• ✅ Chemical Resistance – Inert to common domestic and commercial waste stream compositions
• ✅ Non-Corrosive Construction – Will not degrade from internal moisture, airborne contaminants, or standard cleaning agents
• ✅ Reduced Friction Loss – Smooth interior walls support efficient flow and minimize the likelihood of buildup or blockages

Installation Guidelines

To ensure a permanent and watertight joint, solvent cement and primer conforming to ASTM F656 and F493 should be used. Pipe ends must be square-cut, deburred, and thoroughly cleaned. Full insertion depth should be verified before bonding. Allow sufficient cure time as recommended by the adhesive manufacturer before system testing or activation.

Application Use Cases

This coupling is commonly installed at branch connections, fixture arms, or mainline transitions where a reduction in pipe diameter is required. It is suitable for slab penetrations, crawl space layouts, and vertical stack offsets in DWV systems designed for gravity drainage without internal pressure.

Material Note

Schedule 40 PVC used in DWV systems offers a balance of structural rigidity, low weight, and resistance to biological growth, scaling, and internal corrosion. This fitting is intended for use in non-pressurized applications with intermittent temperatures up to 140°F (60°C).

The 4" x 3" PVC DWV reducing coupling provides a stable, long-life transition between pipe sizes and is manufactured to meet the dimensional and performance requirements of modern drainage infrastructure.