UL 521
Standard for Heat Detectors for Fire Protective Signaling Systems

DETAILS
Edition Number:7SCC Approved:--
Edition Date:1999-02-19DOD Approved: --
Price Code:AANSI Approved: 2016-10-12
Type:ulstd

  • SCOPE

    1 Scope

    1.1 These requirements cover heat detectors for fire protective signaling systems intended to be installed in ordinary indoor and outdoor locations in accordance with the Standard for Automatic Fire Detectors, NFPA 72E.

    1.2 Heat detectors covered by these requirements employ either normally open contacts or normally closed contacts, provide an electronic signal, or consist of a heat-sensitive cable. The requirements do not cover heat detectors for journal-alarm or unit-alarm devices.

    1.3 Deleted October 3, 2002

  • TABLE OF CONTENTS
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    • Cover
    • Transmittal
    • Table of Contents
    • UL Foreword
      • Body
        • INTRODUCTION
          • 1 Scope
          • 2 General
            • 2.1 Components
            • 2.2 Units of measurement
            • 2.3 Undated references
          • 3 Glossary
          • 4 Installation and Operating Instructions
          • 5 Compatibility Information
            • 5.1 General
            • 5.2 Method of evaluation
            • 5.3 Changes affecting compatibility
          • 6 Temperature Designation
        • CONSTRUCTION
          • GENERAL
          • 7 Mounting
          • 8 Servicing and Maintenance Protection
          • 9 Materials
          • FIELD-WIRING CONNECTIONS
          • 10 Leads
          • 11 Terminals
          • COMPONENTS – ELECTRICAL
          • 12 General
            • 12.1 Insulating material
            • 12.2 Current-carrying parts
          • 13 Contacts
          • SPACINGS – ELECTRICAL
          • 14 General
        • PERFORMANCE
          • GENERAL
          • 15 Test Units and Data
            • 15.1 General
            • 15.2 Component reliability data
            • 15.3 Miscellaneous data
          • 16 Test Voltages
          • 17 Test Samples
          • 18 Sensitivity-Spacing Allocation
          • TESTS
          • 19 Oven Test
          • 20 Fire Test
          • 21 High-Temperature Exposure Test
          • 22 Operating Temperature Test
          • 23 Rate-of-Rise Operation Test
          • 24 Low-Temperature Exposure Test
          • 25 Corrosion Tests
            • 25.1 General
            • 25.2 Indoor-use heat detectors
            • 25.3 Outdoor-use heat detectors
          • 26 Determination of Stress Cracking Test
            • 26.1 General
            • 26.2 Ammonia stress cracking test
            • 26.3 Salt immersion cycling test
          • 27 Bond Secureness Test
          • 28 Humidity Test
          • 29 Transient Tests
            • 29.1 General
            • 29.2 Internally induced transients
            • 29.3 Extraneous transients
            • 29.4 Supply line (high-voltage) transients
            • 29.5 Supply line (low-voltage circuit) transients
          • 30 Vibration Test
          • 31 Overload Tests
            • 31.1 Electronic heat detector
            • 31.2 Separately energized circuits and non-electric type heat detectors
          • 32 Endurance Tests
            • 32.1 Electronic heat detector
            • 32.2 Separately energized circuits and non-electric type heat detectors
          • 33 Rain Test
          • 34 Dielectric Voltage-Withstand Test
          • 35 Marking Label Adhesion Tests
            • 35.1 General
            • 35.2 Air oven-aging test
            • 35.3 Immersion test
            • 35.4 Standard-atmosphere test
            • 35.5 Unusual-condition exposure test
          • 36 Circuit Measurement Test
          • 37 Overvoltage and Undervoltage Tests
            • 37.1 General
            • 37.2 Undervoltage test
          • 38 Component Temperature Test
          • 39 Electrical Supervision Test
          • 40 Stability Test
          • 41 Dynamic Load Immunity Test
          • 42 Polarity Reversal Test
          • 43 Replacement Test, Head and Cover
          • 44 Jarring Test
          • 45 Static Discharge Test
          • 46 Dust Test
          • 47 Tests on Polymeric Materials
            • 47.1 General
            • 47.2 Temperature test
            • 47.3 Flame test
            • 47.4 Impact test
          • 48 Strain Relief Test
          • 49 Abnormal Operations Test
        • MANUFACTURING AND PRODUCTION TESTS
          • 50 General
          • 51 Production Line Dielectric Voltage-Withstand Test for High-Voltage Products
          • 52 Sensitivity Calibration Tests
            • 52.1 Rate-of-rise heat detectors
            • 52.2 Fixed-temperature heat detectors
        • MARKING
          • 53 General
          • 54 Installation Instructions – Wiring Diagram
            • 54.1 General
            • 54.2 Four-wire detectors
            • 54.3 Two-wire detectors
          • 55 Technical Bulletin
    • CRITERIA FOR ACCEPTANCE OF MICROELECTRONIC DEVICES
    • APPENDIX A