1 - AS 1681-2002 SAFETY REQUIREMENTS FOR ELECTRICALLY HEATED TYPE 1 OVENS IN WHICH FLAMMABLE VOLATILES OCCUR
4 - PREFACE
5 - CONTENTS
6 - FOREWORD
7 - SECTION 1 SCOPE AND GENERAL
7 - 1.1 SCOPE
7 - 1.2 OBJECTIVE
7 - 1.3 APPLICATION
7 - 1.4 REFERENCED DOCUMENTS
8 - 1.5 DEFINITIONS
8 - 1.5.1 Batch process oven
8 - 1.5.2 Continuous process oven
8 - 1.5.3 Dielectric heater
8 - 1.5.4 Flashpoint
8 - 1.5.5 Fresh air
8 - 1.5.6 Ignition temperature (of an explosive gas atmosphere)
9 - 1.5.7 Induction heater
9 - 1.5.8 Infrared heater
9 - 1.5.9 Infrared lamp heater
9 - 1.5.10 Natural atmosphere
9 - 1.5.11 Oven
9 - 1.5.12 Prepared atmosphere
9 - 1.5.13 Resistance heater
9 - 1.5.14 Type 1 oven
9 - 1.6 ELECTRICAL SAFETY REQUIREMENTS
9 - 1.7 COMPLIANCE WITH REGULATORY AUTHORITIES, REQUIREMENTS
10 - SECTION 2 CONSTRUCTION REQUIREMENTS
10 - 2.1 GENERAL REQUIREMENTS
10 - 2.1.1 Ovens and related equipment
10 - 2.1.2 Materials
10 - 2.1.3 Interior surfaces
10 - 2.1.4 Insulating materials in walls
10 - 2.1.5 Expansion
10 - 2.1.6 Doors
11 - 2.1.7 Guarding of moving parts
11 - 2.1.8 Shelves
11 - 2.2 EQUIPOTENTIAL BONDING
11 - 2.3 EXPLOSION-RELIEF VENTS
11 - 2.3.1 Basic requirements
11 - 2.3.2 Location in oven
12 - 2.3.3 Adjacent areas and obstructions
13 - 2.4 DUCTS
14 - SECTION 3 HEATING SYSTEMS
14 - 3.1 ELECTRICAL INSTALLATION
14 - 3.2 CONTROLS
14 - 3.3 RESISTANCE HEATERS
14 - 3.3.1 Construction
14 - 3.3.2 Protection against contact
14 - 3.3.3 Location
15 - 3.4 INDUCTION AND DIELECTRIC HEATERS
15 - 3.4.1 Installation
15 - 3.4.2 Construction
16 - SECTION 4 VENTILATION
16 - 4.1 DESIGN CONSIDERATIONS
16 - 4.1.1 General
16 - 4.1.2 Basis for determination of fresh air requirements
16 - 4.1.3 Air circulation
17 - 4.2 RATE OF VENTILATION
17 - 4.3 MECHANICAL VENTILATION
17 - 4.4 FRESH AIR SUPPLY
17 - 4.5 EXHAUST AIR
17 - 4.6 DAMPERS
17 - 4.7 FANS
18 - 4.8 VENTILATION CONTROLS
18 - 4.8.1 Preventilation and purging
18 - 4.8.2 Interlocks
19 - SECTION 5 MARKING
19 - 5.1 GENERAL
19 - 5.2 ADDITIONAL INFORMATION
20 - APPENDIX A - COMBUSTION CHARACTERISTICS FOR COMMON FLAMMABLE LIQUIDS
25 - APPENDIX B - METHODS FOR CALCULATION OF VENTILATION
25 - B1 INTRODUCTION
25 - B2 MEASUREMENT OF QUANTITY OF AIR EXHAUSTED FROM AN OVEN
25 - B3 AIR DILUTION
26 - B4 BASIC CALCULATION
26 - B5 AMOUNT OF VAPOUR PRODUCED PER LITRE OF SOLVENT EVAPORATED (Vm3/L)
27 - B6 AMOUNT OF AIR REQUIRED TO RENDER 1 m3 OF SOLVENT VAPOUR BARELY EXPLOSIVE (A m3/m3)
27 - B7 ESTIMATION OF VA
27 - B7.1 Calculation when either V or A is unknown
27 - B7.2 Calculation for mixed solvents
27 - B7.3 Continuous process ovens
27 - B7.4 Batch process ovens
28 - B8 SAFETY FACTOR C
28 - B9 MAXIMUM INSTANTANEOUS EVAPORATION RATE OF LIQUID SOLVENT (Q L/s or mL/s)
28 - B9.1 Continuous process oven
28 - B9.2 Batch process ovens
29 - B10 TEMPERATURE/VOLUME CORRECTION
29 - B11 EXAMPLES OF CALCULATIONS
29 - B11.1 Continuous oven
30 - B11.2 Batch oven, below 120°C
30 - B11.3 Batch oven above 120°C
33 - APPENDIX C - OVEN SAFETY DESIGN FORM

Specifies requirements for the design, construction and safe operation of ovens for use at a maximum temperature of 540 degrees Celsius in which there may be an explosion hazard due to the presence of flammable volatiles. Appendices provide combustion characteristics for common flammable liquids, methods for calculation of ventilation and illustrate an oven safety design form.

This Standard sets out the requirements for the design, construction and ventilation of electrically heated Type 1 ovens.It also provides guidelines for the location and operation of such ovens.Compliance with this Standard does not imply compliance with the Standards of the AS 2380 series and/or AS/NZS 60079 series and/or the AS 2381 series.

First published as AS C360-1965.Revised and redesignated as AS 1681-1974.Second edition 2002.Reconfirmed 2013. Originated as AS C360-1965. Previous edition AS 1681-1974. Second edition 2002.