UL 10C Positive Pressure Fire Door Endurance: 850°C Melting Point Mandate
Engineering Overview: Technical analysis of UL 10C positive pressure fire testing for lock cylinders, mandating >= 850°C solid brass/steel melting points.
Technical & Engineering Specifications
| Post-Fire Test | Withstands 30 psi high-pressure fire hose stream |
|---|---|
| Material Requirement | Melting Point >= 850°C (Solid Brass or Steel Only) |
| Fire Endurance Ratings | 30, 60, 90, 120 Minutes |
| Fire Testing Standards | UL 10C / NFPA 252 / EN 1634-1 |
Fire Corridor Life Safety
Lock cylinders installed in commercial fire barriers must maintain door latching during furnace exposure exceeding 1,000°C under UL 10C and EN 1634-1.
The Melting Point Mandate
- Prohibition of Zinc: Die-cast zinc alloy melts at ~420°C, leaving an open through-hole that allows flame and toxic smoke passage.
- Solid Brass / Steel ($\ge 850^\circ ext{C}$): Solid extruded brass (melting point ~930°C) and steel cylinders maintain positive structural containment throughout 60/90/120-minute furnace tests.
Frequently Asked Engineering & Selection Questions
Q1: Why is zinc alloy banned on UL 10C fire doors?
Zinc alloy melts at ~420°C, which would burn through during a structural fire and allow toxic smoke and flames to penetrate the door.