National Marker N350769 Square Spring Door Hinge 3.5 in

Product Description

The NATIONAL MARKER N350769 is a 3.5-inch square spring door hinge finished in oil rubbed bronze, part of the V520 series. It is designed to control door closing speed in fire-rated and standard door assemblies across residential, commercial, industrial, and institutional applications. The hinge features adjustable tension so closing force and speed can be tuned to match door weight and traffic demands. Cold-rolled steel construction provides the structural integrity required for listed fire-rated openings. Licensed contractors and finish carpenters typically install this component as part of a complete door hardware package.

The N350769 fits standard hinge cutouts with square corners, making it a direct drop-in replacement in most door prep configurations. It is suited for interior and exterior doors in light commercial and residential settings where self-closing hardware is required by code or building specification. Its adjustable closing speed makes it appropriate for high-traffic corridors, stairwell doors, and unit-entry doors in multi-family or institutional facilities.

Key Features

• Adjustable tension allows field-tuning of closing force to match door weight and use conditions
• Adjustable closing speed for consistent, controlled door movement
• Listed for fire-rated door openings per applicable fire-door assembly requirements
• Fits standard hinge cutout with square corners for straightforward installation
• Cold-rolled steel construction for durability in high-use environments
• Oil rubbed bronze finish suitable for residential and commercial aesthetic requirements

Compatibility

Designed as an OEM-style replacement spring hinge for standard door preparations requiring a 3.5-inch square-corner hinge mortise in fire-rated and non-rated door assemblies.

Installation Notes

Installation is typically performed by a licensed finish carpenter, door hardware installer, or general contractor. Power down or disengage any electronic access control hardware before removing existing hinges. Verify that the door frame and door edge are prepped to accept a 3.5-inch square-corner mortise before installation. When used in fire-rated openings, confirm the complete door assembly — frame, door, hardware, and hinge — meets the listing requirements of the applicable fire-door standard.

Technical Specifications

• Hinge Size: 3.5 inches square
• Corner Style: Square
• Finish: Oil Rubbed Bronze
• Material: Cold-Rolled Steel
• Fire Rating: Listed for fire-rated openings
• Closing Speed: Adjustable
• Tension: Adjustable
• Weight: 0.792 pounds
• Series: V520
• Sold As: Each

Standard Information

• Brand: NATIONAL MARKER
• Manufacturer Part Number: N350769