1、UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULNational Differences ForUL 60079-31Explosive Atmospheres - Part 31: Equipment Dust Ignition Protection by Enclosure tUL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION
2、 WITHOUT PERMISSION FROM ULNational Differences ForUL 60079-31Explosive Atmospheres - Part 31: Equipment Dust Ignition Protection by Enclosure tEdition: 2Edition Date: June 12, 2015Adoption of IEC 60079-31, Explosive Atmospheres Part 31: Equipment Dust IgnitionProtection by Enclosure “t” (second edi
3、tion issued November 2013) as a new IEC-basedUL standard, UL 60079-31 (IEC 60079-31:2013), with US National Differences.This document provides a single listing of the National Differences included in the UL adoption ofthe corresponding IEC standard.All rights reserved. No part of this publication ma
4、y be reproduced, stored in a retrieval system, ortransmitted in any form by any means, electronic, mechanical photocopying, recording, or otherwisewithout prior permission of UL.UL provides this standards document as is without warranty of any kind, either expressed or implied,including but not limi
5、ted to, the implied warranties of merchantability or fitness for any purpose.In no event will UL be liable for any special, incidental, consequential, indirect or similar damages,including loss of profits, lost savings, loss of data, or any other damages arising out of the use of or theinability to
6、use this standards document, even if UL or an authorized UL representative has been advisedof the possibility of such damage. In no event shall ULs liability for any damage ever exceed the pricepaid for this standards document, regardless of the form of the claim.Users of the electronic versions of
7、ULs Standards for Safety agree to defend, indemnify, and hold ULharmless from and against any loss, expense, liability, damage, claim, or judgment (including reasonableattorneys fees) resulting from any error or deviation introduced while purchaser is storing an electronicStandard on the purchasers
8、computer system.Copyright 2015 Underwriters Laboratories Inc.JUNE 12, 2015NATIONAL DIFFERENCES FOR UL UL 60079-312UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULPrefaceThis document provides a single listing of the technical National Differen
9、ces included in the UL adoptionof the corresponding IEC standard.In its IEC-based standards, UL uses the notations indicated below to identify national difference type, andthese types are additionally noted in this document. The standard may not use all types of thesedeviations.D1 - These are deviat
10、ions which are based on basic safety principles and requirements, elimination ofwhich would compromise safety for U.S. consumers and users of products.D2 - These are deviations based on safety practices. These are deviations for IEC requirements that maybe acceptable, but adopting the IEC requiremen
11、ts would require considerable retesting or redesign on themanufacturers part.DC - These are deviations based on the component standards and will not be deleted until a particularcomponent standard is harmonized with the IEC component standard.DE - These are deviations based on editorial comments or
12、corrections.DR - These are deviations based on the national regulatory requirements.Each national difference contains a description of what the national difference entails. Typically one of thefollowing words is used to explain how the text of the national difference is to be applied to the base IEC
13、text:Addition / Add - An addition entails adding a complete new numbered clause, subclause, table,figure, or annex. Addition is not meant to include adding select words to the base IEC text.Deletion / Delete - A deletion entails complete deletion of an entire numbered clause, subclause,table, figure
14、, or annex without any replacement text.Modification / Modify - A modification is an altering of the existing base IEC text such as theaddition, replacement or deletion of certain words or the replacement of an entire clause,subclause, table, figure, or annex of the base IEC text.JUNE 12, 2015 NATIO
15、NAL DIFFERENCES FOR UL UL 60079-31 3UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULNational Differences1DV.1 DR Modification of Clause 1, first and second paragraphs to replace with thefollowing:1DV.1.1 This part of IEC 60079 standard is appl
16、icable to electrical equipment protected byenclosure and surface temperature limitation for use in explosive dust atmospheres. Itspecifies requirements for design, construction and testing of electrical equipment and ExComponents.This standard supplements and modifies the general requirements of UL
17、IEC 60079-0.Where a requirement of this standard conflicts with a requirement of UL IEC 60079-0, therequirement of this standard takes precedence.1DV.2 DR Addition of 1DV.2.11DV.2.1 Where references are made to other IEC 60079 standards, the referencedrequirements found in these standards apply as m
18、odified by any applicable U.S. NationalDifferences.2DV D1 Modification of Clause 2 references to replace with the following:IEC 60079-0, Explosive atmospheres - Part 0: Equipment - General requirementsIEC 60127 (all parts), Miniature fusesIEC 60529, Degrees of Protection Provided by Enclosures (IP c
19、ode)IEC 60691, Thermal-links Requirements and application guideISA 60079-0, Explosive atmospheres Part 0: Equipment General requirementsISO 965-1, ISO general-purpose metric screw threads Tolerances Part 1: Principles andbasic dataUL 60079-0 Explosive atmospheres Part 0: Equipment General requiremen
20、tsUL 248 Series Low-Voltage Fuses4.3.5.1DV.1 DR Modification of Clause 4.3.5.1, second paragraph to replace with thefollowing:4.3.5.1DV.1.1 Where the external protective device is not provided by the manufacturer aspart of the electrical equipment, the marking to indicate the Specific Conditions of
21、Useshall be in accordance with include the symbol “X” in accordance with IEC 60079-0 UL60079-0, and the specific Conditions of Use shall detail the required ratings andcharacteristics of the protective device. The protective device shall be capable ofinterrupting the maximum current of the circuit i
22、n which it is installed. If the electricalequipment contains a cell or battery and a control device is provided to preventJUNE 12, 2015NATIONAL DIFFERENCES FOR UL UL 60079-314UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULoverheating of the c
23、ell or battery, the control device can also be considered as a protectivedevice, provided it also protects the complete electrical equipment from exceeding themaximum surface temperature.4.3.5.2DV D1 Modification of Clause 4.3.5.2 to replace with the following:The electrical equipment shall be prote
24、cted by one or more integral thermal protectivedevices. Thermal protective devices shall not be of a self-resettable type and shall beduplicated unless conforming to IEC 60127 series, UL 248 series, or IEC 60691, in whichcase only one device is necessary.Alternatively, if it can be demonstrated that
25、 an overcurrent protective device can be usedto provide thermal protection, such a device may be used. The overcurrent protectivedevice used in this way shall conform to IEC 60127 series or UL 248 series and shall berated at not more than 170 % of the maximum rated current of the electrical equipmen
26、t.When an overcurrent protective device is not also used as a thermal protective device, itis permissible for the overcurrent protective device to be located outside the enclosure ofthe electrical equipment. In this case, the marking shall include to indicate the SpecificConditions of Use symbol X s
27、hall be in accordance with IEC 60079-0 UL 60079-0 and theSpecific Conditions of Use shall detail the required overcurrent protective device. Theresponse time of the thermal protective devices should be taken into account and beadequate for the necessary overtemperature protection.NOTE When no such i
28、nformation exists, a common practice is to use 1.7 rated current.4.4.1DV DR Modification of Clause 4.4.1 to replace with the following:The marked maximum surface temperature shall be measured on the external surfaces ofthe enclosure for electrical equipment with types of protection “tb” and “tc in a
29、ccordancewith 6.1.2DV with no dust layer on the external surfaces under normal operatingconditions.5.1.2DV DR Modification of Clause 5.1.2 to replace the first bullet item with thefollowing: The number of engaged threads for all threaded joints, employing parallel threadswithout an additional seal o
30、r gasket shall be not less than five threads and with a tolerancequality of medium or fine according to ISO 965-1. Tapered threaded joints without anadditional seal or gasket shall engage no less than 3-1/2 threads.NOTE The requirement for threaded entries differs from the requirement shown in 5.1.2
31、 and is found in 5.3.2.5.2DV DR Modification of Clause 5.2 to replace with the following:Cable glands, whether integral or separate, shall meet the requirements of IEC 60079-0 UL60079-0, and the joint requirements of 5.1. In addition, cable glands shall meet therequirements of Table 1.Where cable gl
32、ands are separate: threaded cable glands may be evaluated as Ex Equipment cable gland, other cable glands may be evaluated only as an Ex Component,JUNE 12, 2015 NATIONAL DIFFERENCES FOR UL UL 60079-31 5UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION
33、FROM UL cable glands with other thread forms to those specified here may be evaluated onlywith the electrical equipment or as an Ex component. the entry thread requirements of 5.3.2 shall be applied in place of those in 5.1.2.NOTE UL 60079-0 states that cable glands or cord connectors, whether integ
34、ral or separate, shall comply with UL2225.5.3.2DV DR Modification of Clause 5.3.2 to replace with the following:Threaded entries are considered to meet the requirements for “ta”, “tb” and “tc” electricalequipment if they are: Tapered threads with not less than 3 threads, Parallel threads with not le
35、ss than five threads, with a tolerance class of 6H or betteraccording to ISO 965-1, Parallel threads with less than five threads with a tolerance class of 6H or betteraccording to ISO 965-1 and are provided with an additional seal or gasket. If the additionalseal is not an integral part of the elect
36、rical equipment, the marking shall include thesymbol X in accordance with IEC 60079-0 and the Specific Conditions of Use that shalldetail the required use of a seal or gasket. An advisory marking of the requirement for aseal or gasket may appear on the electrical equipment as an alternative to the r
37、equirementfor the “X” marking.NOTE In accordance with UL 60079-0, an advisory marking of the requirement for a seal or gasket may appear onthe electrical equipment as an alternative to the requirement for indicating the Specific Conditions of Use.6.1.1.3DV DE Modification of Clause 6.1.1.3 to replac
38、e with the following:A positive internal pressure of at least:40,4 kPa for level of protection “ta” electrical equipment, or20,2 kPa for level of protection “tb” and “tc” electrical equipment,shall be applied to the electrical equipment for 60+100s. Any breathing or draining devicemay be sealed for
39、this test if the pressure cannot be maintained shall be removed and thesample shall be subjected to the IP test in the condition it is in after the completion of thistest. This test is not required for cable glands evaluated as Ex Equipment cable gland.If the design of the electrical equipment is su
40、ch that any gaskets or seals are physicallyconstrained from moving, e.g. an “O” ring in a groove, this test is not required to beconducted for “tb” and “tc” electrical equipment.6.1.1.4DV DE Modification of Clause 6.1.1.4 to replace with the following:The samples shall be IP tested for the different
41、 level of protection as given in Table 1. Anygrease in the joints shall be removed before the IP test is performed.NOTE It is the intent that any excessive grease be removed from the joint prior to the IP testing. It is recognizedthat some grease may need to be present on a threaded joint or o-ring
42、to allow assembly and disassembly.JUNE 12, 2015NATIONAL DIFFERENCES FOR UL UL 60079-316UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM UL6.1.2DV DR Modification of Clause 6.1.2 to replace with the following:For “tb” and “tc” electrical equipment
43、 the test shall be carried out as described in IEC60079 UL 60079-0. For level of protection “tb” equipment, the maximum surfacetemperature shall be determined with the equipment mounted in accordance with themanufacturers instructions with the additional requirement that the apparatus shall becovere
44、d with the maximum amount of dust that it can retain.For “ta” electrical equipment, the maximum surface temperature test of IEC 60079-0 UL60079-0 is conducted with the electrical equipment surrounded by at least a 200 mm layerof dust on all sides. The final temperature shall have been considered to
45、have beenreached when the rate of rise of temperature does not exceed 1 K/24h. This test is carriedout as described in IEC 60079-0 UL 60079-0 and with one additional fault applied to theelectrical equipment.NOTE See IEC 60079-0 for the specification of the test dustNOTE The U.S. national differences
46、 for testing with dust layers in all cases are necessary to align with Article 506of the NEC, which addresses dust layers differently than IEC 60079-14.For ta, the measurement for the maximum surface temperature shall be determined usinga test dust having a thermal conductivity of no more than 0.10
47、W/(m.K) measured at (100 5)C.For tb, the measurement for the maximum surface temperature shall be determined usinga test dust having a thermal conductivity of no more than 0.10 W/(m.K) measured at (100 5)C, or grain dust (corn or wheat).JUNE 12, 2015 NATIONAL DIFFERENCES FOR UL UL 60079-31 7UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULJUNE 12, 2015NATIONAL DIFFERENCES FOR UL UL 60079-318No Text on This Page
