1、UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL UL 726 Oil-Fired Boiler AssembliesUL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM ULUL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER RE
2、PRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL UL Standard for Safety for Oil-Fired Boiler Assemblies, UL 726 Seventh Edition, Dated November 30, 1995 Summary of Topics This revision to UL 726 is being issued to remove the reference to the withdrawal date of UL 873 and to address universal up
3、keep of UL Standards for Safety. These revisions are considered to be non-substantive and not subject to ULs STP process. Text that has been changed in any manner or impacted by ULs electronic publishing system is marked with a vertical line in the margin. Changes in requirements are marked with a v
4、ertical line in the margin and are followed by an effective date note indicating the date of publication or the date on which the changed requirement becomes effective. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form by any
5、 means, electronic, mechanical photocopying, recording, or otherwise without prior permission of UL. UL provides this Standard as is without warranty of any kind, either expressed or implied, including but not limited to, the implied warranties of merchantability or tness for any purpose. In no even
6、t will UL be liable for any special, incidental, consequential, indirect or similar damages, including loss of prots, lost savings, loss of data, or any other damages arising out of the use of or the inability to use this Standard, even if UL or an authorized UL representative has been advised of th
7、e possibility of such damage. In no event shall ULs liability for any damage ever exceed the price paid for this Standard, regardless of the form of the claim. Users of the electronic versions of ULs Standards for Safety agree to defend, indemnify, and hold UL harmless from and against any loss, exp
8、ense, liability, damage, claim, or judgment (including reasonable attorneys fees) resulting from any error or deviation introduced while purchaser is storing an electronic Standard on the purchasers computer system. The requirements in this Standard are now in effect, except for those paragraphs, se
9、ctions, tables, gures, and/or other elements of the Standard having future effective dates as indicated in the note following the affected item. The prior text for requirements that have been revised and that have a future effective date are located after the Standard, and are preceded by a SUPERSED
10、ED REQUIREMENTS notice. OCTOBER 9, 2013 UL 726 tr1UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL OCTOBER 9, 2013 UL 726 tr2 No Text on This PageUL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSI
11、ON FROM UL NOVEMBER 30, 1995 (Title Page Reprinted: October 9, 2013) 1 UL 726 Standard for Oil-Fired Boiler Assemblies First Edition June, 1955 Second Edition November, 1963 Third Edition June, 1973 Fourth Edition May, 1974 Fifth Edition October, 1975 Sixth Edition September, 1990 Seventh Edition No
12、vember 30, 1995 This UL Standard for Safety consists of the Seventh edition including revisions through October 9, 2013. The Department of Defense (DoD) has adopted UL 726 on January 27, 1992. The publication of revised pages or a new edition of this Standard will not invalidate the DoD adoption. Co
13、mments or proposals for revisions on any part of the Standard 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 http:/. ULs Standards for Safety are copyrighted by UL. Neither a printed nor ele
14、ctronic copy of a Standard should be altered in any way. All of ULs Standards and all copyrights, ownerships, and rights regarding those Standards shall remain the sole and exclusive property of UL. COPYRIGHT 2013 UNDERWRITERS LABORATORIES INC.UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRO
15、DUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL APRIL 6, 2011 OIL-FIRED BOILER ASSEMBLIES - UL 726 2 No Text on This PageUL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL CONTENTS INTRODUCTION 1 Scope .5 2 General 5 3 Glossary .5 3A Undated
16、 References .8 4 Components 8 CONSTRUCTION 5 Assembly .8A 6 Accessibility for Servicing .8B 6A Air-Intake Terminal .8C 6B Vent-Air Intake Assemblies .9 7 Casing 10 8 Radiation Shields or Liners 10 9 Combustion Chamber 11 10 Baffles.11 11 Flue collar .13 12 Damper and Draft Regulator .13 13 Controls
17、.13 13.1 Application 13 13.2 Limit controls 14 13.3 Primary safety control .14A 13.4 Liquid level limit controls 17 13.5 Pressure limit controls 18 13.6 Temperature limit controls .18 13.7 Purge and combustion air monitoring controls .19 13.8 Safety shut-off valves .20 14 Installation of External Co
18、ntrols and Fittings 20 15 Field Wiring .20A 15.1 General 20A 15.2 Leads and Terminals .23 16 Internal Wiring 24 16.1 General .24 16.2 Short-circuit protection 28 17 Separation of Circuits .28 18 Bonding for Grounding 30 ELECTRICAL COMPONENTS 19 General Components and Devices 32B 20 Mounting of Elect
19、rical Components .33 21 Electrical Enclosures 33 21.1 General .33 21.2 Accessibility of uninsulated live parts and lm-coated wire .37 21.3 Boilers having an input in excess of 3 gph (11.4 L/h) .37 21.4 Boilers having an input of 3 gph (11.4 L/h) or Less .40 21.5 Doors and covers .42A 21.6 Field wiri
20、ng system connection .44 APRIL 6, 2011 OIL-FIRED BOILER ASSEMBLIES - UL 726 2AUL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL 22 Motors and Motor Overload Protection 44 23 Overcurrent Protection of High-Voltage Control-Circuit Conductors 48A
21、 23.1 General 48A 23.2 Direct-connected high-voltage control circuit 48A 23.3 Tapped high-voltage control circuits .48A 23.4 Overcurrent-protective devices 48B 24 Overcurrent Protection of Transformers 50 24.1 High-voltage transformers .50 24.2 Low-voltage transformers 51 25 Switches and Controllers
22、 52 26 Capacitors .53 27 Insulating Material 54 SPACINGS 28 High-Voltage Circuits 54 29 Low-Voltage Circuits 55 PROTECTION OF USERS AND SERVICE PERSONNEL 30 General 55 PERFORMANCE 31 General 58 32 Test Installation for Standard Clearances 60 32.1 Enclosure .60 32.2 Chimney connector .62 33 Test Inst
23、allation for Alcove or Closet 64 33.1 Enclosure .64 33.2 Chimney connector .66 34 Instrumentation .68 34.1 Draft 68 34.2 Fuel input .68 34.3 Power measurement 68 34.4 Speed measurement .68 34.5 Temperature measurement 68 35 Initial Test Conditions 70B 36 Combustion Test Burner and Boiler 70B 37 Oper
24、ation Tests 71 38 Limit Control Cutout Test 72 39 Temperature Tests 72 39A Low Water Cutoff of Boilers Test 76 40 Continuous Operation Test .77 41 Short-Circuit Test .77 42 Overload Test, High-Voltage Transformers .79 43 Burnout Test, High-Voltage Transformers 79 43A Direct Vent System Leakage Test
25、.80 43B Wind Tests 80B 43C Rain Test .80C 43D Load Test .80F 43E Impact Test 80F 44 Dielectric Voltage-Withstand Test 80J APRIL 6, 2011 OIL-FIRED BOILER ASSEMBLIES - UL 726 2BUL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL MANUFACTURING AND
26、PRODUCTION TESTS 45 General 81 46 Production Line Dielectric Withstand Test 81 MARKING 47 General 82 INSTALLATION INSTRUCTIONS 48 General 84A APPENDIX A APRIL 6, 2011 OIL-FIRED BOILER ASSEMBLIES - UL 726 3UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISS
27、ION FROM UL This page intentionally left blank. FEBRUARY 24, 2006 OIL-FIRED BOILER ASSEMBLIES - UL 726 4UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL INTRODUCTION 1 Scope 1.1 These requirements apply to oil-red boiler assemblies. 1.2 Requi
28、rements for the installation and use of oil-burning equipment are included in the Standard of the National Fire Protection Association for the Installation of Oil-Burning Equipment, NFPA No. 31. 1.3 Deleted February 24, 2006 2 General 2.1 The term appliance refers to any equipment covered by this St
29、andard. 2.2 Values stated without parentheses are the requirement. Values in parentheses are explanatory or approximate information. 2.2 revised January 26, 2001 3 Glossary 3.1 For the purpose of this Standard the following denitions apply. 3.1.1 AIR-INTAKE TERMINAL The tting which is located on the
30、 outside of the structure through which the air for combustion is taken from the outside atmosphere. The terminal is intended to be connected to the combustion air intake of the boiler with additional piping. 3.1.1 added January 26, 2001 3.2 AIR SHUTTER An adjustable device for varying the size of t
31、he air inlet or inlets regulating primary and/or secondary air. 3.3 ANTIFLOODING DEVICE A primary safety control 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. 3.4 APPLIANCE FLUE Th
32、e ue passages within the appliance. 3.5 AUTOMATICALLY LIGHTED APPLIANCE An appliance in which fuel to the main burner is normally turned on and ignited automatically. 3.6 BAFFLE An object placed in an appliance to direct the ow of air or ue gases. 3.7 BOILER A closed vessel in which water or some ot
33、her liquid is heated or in which steam is generated or superheated, under pressure or vacuum, by direct application of heat. FEBRUARY 24, 2006 OIL-FIRED BOILER ASSEMBLIES - UL 726 5UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL 3.8 BOILER,
34、HIGH PRESSURE STEAM A boiler in which steam is generated at a pressure higher than 15 psig (103 kPa). 3.9 BOILER, HIGH TEMPERATURE WATER A boiler intended for operation at a pressure exceeding 160 psig (1103 kPa) or at a temperature exceeding 250F (121C) or both. 3.10 BOILER, HOT WATER A boiler that
35、 furnishes hot water at a pressure not exceeding 160 psig (1103 kPa) and at a temperature not exceeding 250F (121C). 3.11 BOILER, LOW PRESSURE STEAM A boiler in which steam is generated at a pressure not exceeding 15 psig (103 kPa). 3.12 BURNER, MECHANICAL ATOMIZING TYPE A power-operated burner whic
36、h 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 burner. 3.13 BURNER, MECHANICAL DRA
37、FT TYPE A burner which includes a power-driven fan, blower, or other mechanism as the principal means for supplying air for combustion. 3.14 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 combustio
38、n. 3.15 CASING An enclosure forming the outside of the appliance, no parts of which are likely to be subjected to intense heat. 3.16 CENTRAL HEATING APPLIANCE A stationary indirect-red vented appliance comprising the following classes: boilers, central furnaces, oor furnaces, and recessed heaters. A
39、 oor-mounted unit heater to be connected to a duct system is categorized also as a central heating appliance. 3.17 COMBUSTIBLE MATERIAL Combustible material as pertaining to materials adjacent to or in contact with heat-producing appliances, chimney connectors and vent connectors, steam and hot wate
40、r pipes, refers to material 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 through ameproofed, re-retardant treated, or plastered. 3.18 COMBUSTION CHAMBER The portion of an appliance with
41、in which combustion occurs. 3.19 CONTROL, LIMIT An automatic safety control, responsive to changes in liquid level, pressure, or temperature, for limiting the operation of the controlled equipment. 3.20 CONTROL, SAFETY Automatic controls, including relays, switches, and other auxiliary equipment use
42、d in conjunction therewith to form a safety control system, that is intended to reduce the risk of re, electric shock, or injury to persons during operation of the controlled equipment. 3.21 CONTROL, PRIMARY SAFETY An automatic control that monitors the operation of a gas-red or an oil-red burner. I
43、t normally consists of the following sections that may be integrated into a common unit or may be separate units, interconnected by wiring: a) Programming Unit A device that programs the burner through start-up and shutdown operations in response to signals from regulating, limiting, and monitoring
44、devices. It also provides the necessary timings, in proper sequence, for purging, pilot ame ignition, main ame ignition, and in case of ignition or ame failure, for safety shutdown (lockout); or JANUARY 26, 2001 OIL-FIRED BOILER ASSEMBLIES - UL 726 6UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER
45、 REPRODUCTION OR DISTRIBUTION WITHOUT PERMISSION FROM UL b) Combustion Detector A device that is responsive to ame properties. It monitors the ame at the point of ame supervision and transmits a signal to the programming unit, indicating absence or presence of ame. 3.22 CONTROL, SAFETY COMBUSTION A
46、primary safety control responsive directly to ame properties, sensing the presence of ame and causing fuel to be shut off in event of ame failure. 3.23 DAMPER A valve or plate for regulating draft or ow of ue gases. A damper is generally considered as being located on the downstream side of the comb
47、ustion chamber, usually in a ue passage of the appliance or in the chimney connector. 3.24 DAMPER, AUTOMATICALLY OPERATED A damper operated by an automatic control. 3.25 DAMPER, MANUALLY OPERATED An adjustable damper manually set and locked in the desired position. 3.25.1 DIRECT VENT SYSTEM, BOILER
48、A boiler which is constructed so that all air supplied for combustion, the combustion system of the boiler, and all products of combustion are completely isolated from the atmosphere of the space in which it is installed. 3.25.1 added January 26, 2001 3.26 DRAFT The differential in static pressure a
49、vailable, between any two locations, to provide the energy potential for the moving of air for combustion or products of combustion through a fuel-burning heat-exchanging apparatus, or both. 3.27 DRAFT REGULATOR A device which functions to maintain a desired draft in the appliance by automatically reducing the chimney draft to the desired value. 3.28 ELECTRICAL CIRCUITS: a) High-Voltage Circuit A circuit involving a pot
