1、UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL UL 731 Oil-Fired Unit Heaters STANDARD FOR SAFETYUL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM ULUL COPYRIGHTED MATERIAL NOT AUTHORIZED
2、 FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL UL Standard for Safety for Oil-Fired Unit Heaters, UL 731 Sixth Edition, Dated January 31, 2018 Summary of Topics This New Edition of ANSI/UL 731 is being issued to address the editorial maintenance of UL Standards for Safety. All
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7、tandard on the purchasers computer system. JANUARY 31, 2018 UL 731 tr1UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL JANUARY 31, 2018 UL 731 tr2 No Text on This PageUL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBU
8、TION WITHOUT PERMISSION FROM UL JANUARY 31, 2018 1 UL 731 Standard for Oil-Fired Unit Heaters First Edition August, 1955 Second Edition April, 1974 Third Edition May, 1975 Fourth Edition March, 1988 Fifth Edition September, 1995 Sixth Edition January 31, 2018 This ANSI/UL Standard for Safety consist
9、s of the Sixth Edition. The most recent designation of ANSI/UL 731 as a Reaffirmed American National Standard (ANS) occurred on November 22, 2016. ANSI approval for a standard does not include the Cover Page, Transmittal Pages, and Title Page. Comments or proposals for revisions on any part of the S
10、tandard may be submitted to UL at any time. Proposals should be submitted via a Proposal Request in ULs On-Line Collaborative Standards Development System (CSDS) at https:/. ULs Standards for Safety are copyrighted by UL. Neither a printed nor electronic copy of a Standard should be altered in any w
11、ay. All of ULs Standards and all copyrights, ownerships, and rights regarding those Standards shall remain the sole and exclusive property of UL. COPYRIGHT 2018 UNDERWRITERS LABORATORIES INC. UL/ANSI 731-2004 (R2016)UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITH
12、OUT PERMISSION FROM UL JANUARY 31, 2018 OIL-FIRED UNIT HEATERS - UL 731 2 No Text on This PageUL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL CONTENTS INTRODUCTION 1 Scope .6 2 Glossary .6 3 Components 10 CONSTRUCTION 4 Assembly .11 5 Burner
13、s .12 6 Accessibility for Servicing .12 7 Disposal of Combustion Products 13 8 Base .13 9 Casing13 10 Radiation Shields and Materials in Air-Handling Compartments.13 11 Air Filter .14 12 Combustion Chamber .14 13 Radiator .14 14 Heating Surface Joints 15 15Baffles.15 16 Flue Collar .16 17 Damper and
14、 Draft Regulator .16 18 Controls .16 18.1 Application 16 18.2 Limit control .17 19 Field Wiring 17 19.1 General .17 19.2 Leads and terminals 19 20 Internal Wiring21 20.1 General .21 20.2 Methods 21 20.3 Short circuit protection 24 21 Separation of Circuits .24 22 Bonding for Grounding 26 23 Electric
15、al Components General .29 24 Mounting of Electrical Components .29 25 Electrical Enclosures 30 25.1 General .30 25.2 Doors and covers 36 25.3 Field wiring system connection.37 26 Motors and Motor Overload Protection 38 27 Overcurrent Protection of High-Voltage Control-Circuit Conductors42 27.1 Gener
16、al .42 27.2 Direct-connected high-voltage control circuit .42 27.3 Tapped high-voltage control circuits 42 27.4 Overcurrent-protective devices .43 28 Overcurrent Protection of Transformers44 28.1 High-voltage transformers .44 28.2 Low-voltage transformers45 28.3 Overcurrent protective devices .45 JA
17、NUARY 31, 2018 OIL-FIRED UNIT HEATERS - UL 731 3UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL 29 Switches and Controllers 46 30 Capacitors .46 31 Electrical Insulating Material47 32 High-Voltage Circuits Spacings .47 33 Low-Voltage Circuit
18、s Spacings .48 PROTECTION OF USERS AND SERVICE PERSONNEL 34 General49 PERFORMANCE 35 General52 36 Test Installation Floor-Mounted Heaters .53 36.1 Enclosure .53 36.2 Chimney connector .54 36.3 Air outlet and inlet 57 37 Test Installation Suspended Type Heaters .57 37.1 Enclosure .57 37.2 Chimney con
19、nector .57 37.3 Air outlet and inlet 59 38 Instrumentation .59 38.1 Draft 59 38.2 Fuel input .59 38.3 Power measurement59 38.4 Speed measurement .60 38.5 Temperature measurement 60 39 Initial Test Conditions .62 39.1 General .62 39.2 Heater equipped with mechanical atomizing burner.63 40 Combustion
20、Test Burner and Heater 63 41 Continuous Operation Tests64 42 Limit Control Cutout Test 64 43 Continuity of Operation Test .65 44 Temperature Test.65 45 Continuous Operation Temperatures 65 46 Fan Failure Test 69 47 Stalled Fan Motor Test 69 48 Blocked Inlet Test.70 49 Short Circuit Test .70 50 Overl
21、oad Test, High-Voltage Transformers.73 51 Burnout Test, High-Voltage Transformers 73 52 Dielectric Voltage-Withstand Test .74 MANUFACTURING AND PRODUCTION TESTS 53 General75 MARKING 54 General76 INSTALLATION INSTRUCTIONS JANUARY 31, 2018 OIL-FIRED UNIT HEATERS - UL 731 4UL COPYRIGHTED MATERIAL NOT A
22、UTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL 55 General78 APPENDIX A Standards for ComponentsA1 JANUARY 31, 2018 OIL-FIRED UNIT HEATERS - UL 731 5UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL INTRODUCTION 1
23、 Scope 1.1 These requirements apply to oil-red unit heaters as dened herein. Unit heaters designed to supply heated air through ducts are covered in the Standard for Oil-Fired Central Furnaces, UL 727. 1.2 The oil-burning equipment covered by these requiremetns are intended for installation in accor
24、dance with the National Fire Protection Association Standard for the Installation of Oil Burning Equipment, NFPA 31, the International Mechanical Code and the Uniform Mechanical Code. 1.3 If a value for measurement is followed by a value in other units in parentheses, the second value may be only ap
25、proximate. The rst stated value is the requirement. 2 Glossary 2.1 For the purpose of this standard, the following denitions apply. 2.2 AIR SHUTTER An adjustable device for varying the size of the air inlet or inlets regulating primary or secondary air. 2.3 ANTIFLOODING DEVICE A primary safety contr
26、ol which causes the fuel ow to be shut off upon a rise in fuel level or upon receiving excess fuel, and which operates before the hazardous discharge of fuel can occur. 2.4 APPLIANCE FLUE The ue passages within the appliance. 2.5 AUTOMATICALLY LIGHTED APPLIANCE An appliance in which fuel to the main
27、 burner is normally turned on and ignited automatically. 2.6 BAFFLE An object placed in an appliance to direct the ow of air or ue gases. 2.7 BASE The main supporting frame or structure of the furnace, exclusive of legs. 2.8 BURNER A device for the nal conveyance of fuel or a mixture of fuel and air
28、 to the combustion zone. 2.9 BURNER, AUTOMATICALLY LIGHTED One where fuel to the main burner is normally turned on and ignited automatically. 2.10 BURNER, MANUALLY LIGHTED One where fuel to the main burner is turned on only by hand and ignited under supervision. 2.11 BURNER, MECHANICAL-ATOMIZING TYP
29、E A power-operated burner which prepares and delivers the oil and all or part of the air by mechanical process in controllable quantities for combustion. Some examples are air atomizing, high and low pressure atomizing, horizontal rotary, vertical rotary atomizing, and vertical rotary wall-ame burne
30、rs. JANUARY 31, 2018 OIL-FIRED UNIT HEATERS - UL 731 6UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL 2.12 BURNER, MECHANICAL DRAFT TYPE A burner which includes a power-driven fan, blower, or other mechanism as the principal means for supply
31、ing air for combustion. 2.13 BURNER, NATURAL DRAFT TYPE A burner which depends principally upon the natural draft created in the ue to induce into the burner the air required for combustion. 2.14 BURNER, VAPORIZING TYPE A burner consisting of an oil-vaporizing bowl or other receptacle to which liqui
32、d fuel may be fed in controllable quantities. The heat of combustion is used to vaporize the fuel, with provision for admitting air and mixing it with the oil vapor in combustible proportions. 2.15 CASING An enclosure forming the outside of the appliance, no parts of which are likely to be subjected
33、 to intense heat. 2.16 CENTRAL HEATING APPLIANCE A stationary indirect-red vented appliance comprising the following classes: boilers, central furnaces, oor furnaces, and recessed heaters. A oor-mounted unit heater to be connected to a duct system is classied also as a central heating appliance. 2.1
34、7 CHIMNEY CONNECTOR The pipe which connects a solid or liquid fuel burning appliance to a chimney. 2.18 COMBUSTIBLE MATERIAL Combustible material as pertaining to materials adjacent to or in contact with heat-producing appliances, chimney connectors, vent connectors, and warm air ducts means materia
35、l made of or surfaced with wood, compressed paper, plant bers, or other material that will ignite and burn. Such material shall be considered as combustible even though ameproofed, re retardant treated, or plastered. 2.19 COMBUSTION As used herein, the rapid oxidation of fuel accompanied by the prod
36、uction of heat, or heat and light. Complete combustion of a fuel is possible only in the presence of an adequate supply of oxygen. 2.20 COMBUSTION CHAMBER The portion of an appliance within which combustion occurs. 2.21 COMBUSTION (FLAME) SAFEGUARD A safety combustion control. 2.22 CONSTANT-LEVEL VA
37、LVE A device for maintaining within a reservoir a constant level of fuel for delivery to the burner. 2.23 CONTROL A device designed to regulate the fuel, air, water, or electrical supply to the controlled equipment. It may be automatic, semiautomatic, or manual. 2.24 CONTROL, LIMIT An automatic safe
38、ty control responsive to changes in liquid level, pressure, or temperature used for limiting the operation of the controlled equipment. 2.25 CONTROL, SAFETY Automatic controls (including relays, switches, and other auxiliary equipment used in conjunction therewith to form a safety control system) wh
39、ich are intended to prevent unsafe operation of the controlled equipment. JANUARY 31, 2018 OIL-FIRED UNIT HEATERS - UL 731 7UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL 2.26 CONTROL, PRIMARY SAFETY The automatic safety control intended to
40、 prevent abnormal discharge of oil at the burner in case of ignition failure or ame failure. 2.27 CONTROL, SAFETY COMBUSTION A primary safety control responsive directly to ame properties. It senses the presence of ame and causes fuel to be shut off in event of ame failure. 2.28 DAMPER A valve or pl
41、ate for regulating draft or ow of ue gases. A damper is generally considered as being located on the downstream side of the combustion chamber, usually in a ue passage of the appliance or in the chimney connector. 2.29 DAMPER, AUTOMATICALLY OPERATED A damper operated by an automatic control. 2.30 DA
42、MPER, MANUALLY OPERATED An adjustable damper manually set and locked in the desired position. 2.31 DRAFT REGULATOR A device which functions to maintain a desired draft in the appliance by automatically reducing the chimney draft to the desired value. 2.32 ELECTRICAL CIRCUITS: a) High-Voltage Circuit
43、 A circuit involving a potential of not more than 600 volts and having circuit characteristics in excess of those of a low-voltage circuit. b) Low-Voltage Circuit A circuit involving a potential of not more than 30 volts alternating- current (42.4 peak or direct current) and supplied by a primary ba
44、ttery, a standard Class 2 transformer or other suitable transforming device, or a suitable combination of transformer and xed impedance having output characteristics in compliance with what is required for a Class 2 transformer. A circuit derived from a source of supply classied as a high-voltage ci
45、rcuit, by connecting resistance in series with the supply circuit as a means of limiting the voltage and current, is not considered to be a low-voltage circuit. c) Safety Control Circuit A circuit involving one or more safety controls. 2.33 EXCESS AIR Air which passes through the combustion area and
46、 the appliance ues in excess of that which is theoretically required for complete combustion. 2.34 FLUE The general term for the conduit or passageway through which ue gases pass from the combustion chamber to the outer air. 2.35 FLUE COLLAR That portion of an appliance designed for attachment of th
47、e chimney or vent connector. 2.36 FLUE GASES Combustion products and excess air. 2.37 FUEL OIL Any hydrocarbon oil as dened by Specication for Fuel Oils, ASTM D396-1992. JANUARY 31, 2018 OIL-FIRED UNIT HEATERS - UL 731 8UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION
48、WITHOUT PERMISSION FROM UL 2.38 HEAT EXCHANGER, DIRECT A heat exchanger in which heat generated in the combustion chamber of the appliance is transferred directly through walls of the appliance to the heating medium (such as air, steam, or water) held in close contact with the combustion chamber wal
49、ls. It is a self-contained combustion and heat transfer device, hence a direct heat transfer device. 2.39 HEAT EXCHANGER, INDIRECT A heat exchanger which encloses or contains a heating medium, such as air, steam, or water, the heat from which is transferred to another heating medium separately contained in close contact with or directed through the heat exchanger. It is an indirect heat transfer device. 2.40 HEAT
