National Marker N350793 Square Spring Door Hinge 4 in

Product Description

The NATIONAL MARKER N350793 is a 4-inch square spring door hinge finished in oil rubbed bronze, designed to provide controlled, automatic door closing in a wide range of door applications. Part of the V520 series, this hinge features adjustable closing tension and adjustable closing speed, giving installers precise control over door return performance. It is manufactured from cold-rolled steel and is listed for use in fire-rated door openings, making it a code-appropriate choice where self-closing hardware is required. Square corners and standard hinge cutout dimensions simplify installation on existing door preparations.

This hinge is suited for residential, commercial, industrial, and institutional applications where self-closing doors are required by code or facility policy. Typical installations include corridor doors, stairwell access doors, and unit-entry doors in multifamily housing. The fire-rated listing makes it directly applicable to openings that must meet self-closing requirements under applicable fire and building codes. The oil rubbed bronze finish integrates with common door hardware finishes found in both new construction and retrofit projects.

Key Features

• Listed for fire-rated door openings requiring self-closing hardware
• Adjustable tension allows closing force to be tuned after installation
• Adjustable closing speed for controlled, consistent door return
• Cold-rolled steel construction for durability in high-cycle applications
• Fits standard hinge cutout — no mortise modification required
• Square corners for compatibility with standard door and frame preparations

Compatibility

Designed as an OEM-style replacement or new-installation spring hinge for standard residential and commercial door preparations requiring a 4-inch square-corner hinge.

Installation Notes

Installation is performed by a qualified door hardware installer or finish carpenter following the door manufacturer's hardware schedule and applicable fire-rated assembly requirements. Confirm the door and frame assembly carries the appropriate fire label before installing hardware listed for fire-rated openings. Adjust spring tension using the provided adjustment pin only after the hinge is fully fastened to avoid uncontrolled spring release. Verify closing speed and latching performance after installation per the authority having jurisdiction's requirements for self-closing assemblies.

Technical Specifications

• Size: 4 inches
• Corner Style: Square
• Finish: Oil Rubbed Bronze
• Material: Cold-Rolled Steel
• Fire Rated Listing: Yes
• Closing Tension: Adjustable
• Closing Speed: Adjustable
• Series: V520
• Weight: 0.882 pounds
• Sold As: Each

Standard Information

• Brand: NATIONAL MARKER
• Manufacturer Part Number: N350793