1、 AMERICAN NATIONAL STANDARD ANSI/ISA-61241-1 (12.10.03)-2006 (R2011) Electrical Apparatus for Use in Zone 21 and Zone 22 Hazardous (Classified) Locations Protection by Enclosures “tD” Approved 29 March 2011 ANSI/ISA-61241-1 (12.10.03)-2006 (R2011), Electrical Apparatus for Use in Zone 20, Zone 21 an
2、d Zone 22 Hazardous (Classified) Locations Protection by Enclosures “tD” ISBN: 978-1-936007-89-9 Copyright 2011 by IEC and ISA. All rights reserved. Not for resale. Printed in the United States of America. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in
3、 any form or by any means (electronic mechanical, photocopying, recording, or otherwise), without the prior written permission of the Publisher. ISA 67 Alexander Drive P.O. Box 12277 Research Triangle Park, North Carolina 27709 - 3 - ANSI/ISA-61241-1 (12.10.03)-2006 (R2011) Preface This preface, as
4、well as all footnotes and annexes, is included for information purposes and is not part of ANSI/ISA-61241-1 (12.10.03)-2006 (R2011). This document has been prepared as part of the service of ISA toward a goal of uniformity in the field of instrumentation. To be of real value, this document should no
5、t be static but should be subject to periodic review. Toward this end, the Society welcomes all comments and criticisms and asks that they be addressed to the Secretary, Standards and Practices Board; ISA; 67 Alexander Drive; P. O. Box 12277; Research Triangle Park, NC 27709; Telephone (919) 549-841
6、1; Fax (919) 549-8288; E-mail: standardsisa.org. The ISA Standards and Practices Department is aware of the growing need for attention to the metric system of units in general, and the International System of Units (SI) in particular, in the preparation of instrumentation standards. The Department i
7、s further aware of the benefits to USA users of ISA standards of incorporating suitable references to the SI (and the metric system) in their business and professional dealings with other countries. Toward this end, this Department will endeavor to introduce SI-acceptable metric units in all new and
8、 revised standards, recommended practices, and technical reports to the greatest extent possible. Standard for Use of the International System of Units (SI): The Modern Metric System, published by the American Society for Testing zone 21; 1To be published. - 15 - ANSI/ISA-61241-1 (12.10.03)-2006 (R2
9、011) zone 22 with conductive dust. Dust-protected enclosures, IP5X, shall be applied for use in: zone 22 with non-conductive dust. At present, there are no additional requirements for practice A to those given in IEC 61241-0 and in this standard. 6.2 Joints 6.2.1 General All joints in the structure
10、of the enclosure between surfaces, whether permanently closed or designed to be opened from time to time, shall fit closely together within the tolerances specified in the documentation. They shall be effectively sealed against the ingress of dust and shall comply with the following particular requi
11、rements: The length of thread for all screw joints employing parallel threads shall be not less than five threads. Hinges shall be clear of joints and shall not be used as a means of obtaining a seal unless they are provided with facilities for positive location and correct operation is assured; and
12、 it is not possible for damage to occur to either the hinge or enclosure during normal operation and use; and they are not manufactured from materials that are subject to wear that would affect the correct operation; and correct compression of the gasket is achieved without causing undue movement, s
13、tress or distortion to the gasket. Where necessary a suitable register shall be provided for covers and the like to ensure correct replacement. 6.2.2 Gaskets and seals Gaskets under compression between joint surfaces may be used to ensure the effectiveness of the enclosure sealing. All gaskets shall
14、 be of one-piece continuous construction, i.e. with an uninterrupted periphery. Gaskets, whether of the loose or secured variety, shall be of a form that will provide and maintain in service a dust-excluding seal between the joint surfaces of the enclosure. NOTE Unless all gaskets are either cemente
15、d or moulded into one face of the jointed surface, the design of the enclosure should be such that the inspection of the assembly to determine whether gaskets have been fitted correctly can be made without disturbing the enclosure. A gasket may be cemented to one face only of the joint surface. Gask
16、eted joints shall not be supplemented by the application of a sealant material except on one face only of the joint surfaces. Gaskets shall be of material that is not subject to appreciable ageing or to plastic flow between the envisaged maintenance periods as determined by the tests in 8.1 through
17、8.2.3. ANSI/ISA-61241-1 (12.10.03)-2006 (R2011)- 16 - A flexible seal, e.g. a bellows, shall be such that it is not over-stressed at any point and shall be protected from external mechanical damage and secured at each end by positive mechanical means. 6.2.3 Cemented joints Cemented joints shall comp
18、ly with the following requirements: They shall not be used on lids or covers which have to be removed to gain access to field wiring connections or in-service adjusting facilities. The width of a cemented joint shall be equal to or greater than 5 mm. 6.2.4 Operating rods and spindles Openings in enc
19、losures for rods or spindles shall have means, other than grease or compound, that will prevent the ingress of dust, both when the spindles or rods are in motion and when they are at rest. 6.2.5 Power shafts Openings in enclosures for power shafts shall have means, other than grease or compound, tha
20、t will prevent the ingress of dust, both when the shafts are in motion and when they are at rest. 6.2.6 Windows 6.2.6.1 Cemented windows A cemented window shall be cemented either directly into the wall of the enclosure so as to form with the latter an inseparable assembly, or into a metallic frame
21、such that the assembly can be replaced as a unit. 6.2.6.2 Gasketed windows A gasketed window may be mounted directly in the wall or cover of the enclosure, no separate detachable frame being necessary. It shall incorporate a suitable seal or gasket. 7 Supplementary rRequirements for electrical appar
22、atus protected by enclosures for practice B for use in zone 20 or 21 or 22 7.1 General For apparatus marked for use in zone 21, the tests of 8.2.1.4 shall be conducted. For apparatus marked for use in zone 22, the tests of 8.2.1.5 shall be conducted. 7.2 Joints 7.2.1 Plain joints Plain joints (see F
23、igure 1) shall have a minimum contact width from inside to outside of the enclosure and a maximum allowable clearance between the surfaces as shown in Table 1. - 17 - ANSI/ISA-61241-1 (12.10.03)-2006 (R2011) Table 1 Plain joints Minimum contact width of the plain joint (mm), W 5 22 Maximum allowable
24、 clearance between the surfaces of the joint (mm), G 0,05 0,22 NOTE For widths of joints between 5 mm and 22 mm, the maximum clearance may be increased by 0,01 mm for each millimetre increase in joint width greater than 5 mm. G W IEC 346/04 Figure 1 Plain joints 7.2.2 Spigotted joints Spigotted join
25、ts (see Figure 2), which have axial, L, and radial, W, paths neither of which is less than 1,2 mm, may have diametrical clearances as shown in Table 1 for plain joints. The radial section, W, of the spigotted joint shall have a maximum allowable clearance, G, as shown in Table 1 shown for plain join
26、ts. LGWPart 2Part 1I.D. O.DIEC 347/04Figure 2 Spigotted joints 7.2.3 Gasketed joints For gasketed joints (see Figure 3), requirements are given in Table 2. ANSI/ISA-61241-1 (12.10.03)-2006 (R2011)- 18 - W O IEC 348/04 Figure 3 Gasketed joints Table 2 Gasketed joints Maximum opening dimension (mm), O
27、 305 915 915 Minimum required effective width of gasketed joint (mm), W 3 4,8 9,5 For maximum opening dimensions between 305 mm and 915 mm, the effective width of the gasketed joint shall be increased by 0,003 mm for each millimetre increase in the maximum opening dimension greater than 305 mm. 7.3
28、Operating rods, spindles or shafts 7.3.1 General For apparatus intended for use in zone 20 and 21 and 22, dust exclusion shall not depend on running contact seals. The equipment shall meet the design details of Tables 3 and 4 and the tests of 8.2.1 without the running contact seal installed. 7.3.2 R
29、unning contact seals If running contact seals are used, the equipment shall meet the design details of Tables 3 and 4 and the dust tests of 8.2.1 without the running contact seals installed. 7.3.3 Power shafts Power shafts for transmitting power at rotational speeds of 100 r/min or more (see Figure
30、4), shall meet the requirements for the length of path from the inside to the outside of the enclosure as given in Table 3. - 19 - ANSI/ISA-61241-1 (12.10.03)-2006 (R2011) D1 D2L IEC 349/04 Figure 4 Power shafts for speeds of 100r/min or more Table 3 Power shafts for speeds of 100 r/min or more Mini
31、mum length of path for power shafts (mm), L 12,5 38,5 Maximum allowable diametrical clearance (mm), D2 D1 0,26 0,57 For lengths of path for power shafts between 12,5 mm and 38,5 mm, the maximum diametrical clearance may be increased by 0,012 mm for each millimetre increase in the length of path grea
32、ter than 12,5 mm. NOTE The minimum length of path may include both the inner and outer lips of the bearing housing. 7.3.4 Operating rods Operating rods, spindles or shafts having rotary motion of less than 100 r/min or axial motion, shall have either a threaded joint with three full threads engaging
33、, or have a minimum length of path from the inside to the outside of the enclosure as given in Table 4. Table 4 Power shafts for speeds of less than 100 r/min Minimum length of path for operating rods, spindles or shafts (mm), L 12,5 25,5 Maximum allowable diametrical clearance (mm), D2 D1 0,13 0,21
34、 For lengths of path for operating rods, spindles or shafts between 12,5 mm and 25,5 mm, the maximum diametrical clearance may be increased by 0,006 mm for each millimetre length of path greater than 12,5 mm. 7.4 Clearance of bolts Bolts passing through the enclosure wall shall have a maximum diamet
35、rical clearance between the unthreaded shank of the bolt, N, and the clearance hole in the enclosure, DS-DH, of not more than 0,26 mm and a length of path, L, of not less than 12,5 mm (Figure 5). ANSI/ISA-61241-1 (12.10.03)-2006 (R2011)- 20 - L DHDS N IEC 350/04 Figure 5 Clearance of bolts 8 Verific
36、ation and tests 8.1 General In addition to the verification and testing requirements of IEC 61241-0, the following applies. 8.2 Type tests 8.2.1 Tests for dust exclusion by enclosures 8.2.1.1 General Depending on the environmental conditions likely to be encountered (such as area classification and
37、conductivity of dust) two levels of dust exclusion efficiency have been adopted: “dust-tight” and “dust-protected” enclosures. NOTE For the required degree of dust exclusion efficiency, see IEC 61241-14. In making an assessment for the acceptance of the apparatus following the tests, the effect of t
38、he presence of a combustible dust shall be taken into consideration. The precautions that shall be taken where a combustible dust is used for the tests is left to the discretion of the testing authority or others concerned. 8.2.1.2 Dust-tight apparatus for practice A The apparatus shall be subjected
39、 to the thermal endurance to heat, thermal endurance to cold, and mechanical tests of ANSI/ISA-61241-0. The apparatus shall then be subjected to the pressure test of 8.2.3. EnclosuresFinally, the apparatus, including rotating machines, shall satisfy the requirements for IP6X, as specified in IEC 605
40、29, or IEC 60034-5 as applicable. The apparatus shall be considered as belonging to “Category 1 enclosure” as specified in IEC 60529. - 21 - ANSI/ISA-61241-1 (12.10.03)-2006 (R2011) 8.2.1.3 Dust-protected apparatus for practice A The apparatus shall be subjected to the thermal endurance to heat, the
41、rmal endurance to cold, and mechanical tests of ANSI/ISA-61241-0. The apparatus shall then be subjected to the pressure test of 8.2.3. All enclosuresFinally, the apparatus, including rotating machines, shall satisfy the test and acceptance requirements of IP5X, as specified in IEC 60529 or IEC 60034
42、-5 as applicable. For the purposes of acceptance criteria in accordance with IEC 60034-5, all dusts shall be considered to be conductive and therefore IP5X shall be assessed against the acceptance criteria of IP6X. The apparatus shall be considered as belonging to “Category 1 enclosure” as specified
43、 in IEC 60529. 8.2.1.4 Dust-tight apparatus for practice B 8.2.1.4.1 Heat cycling test a) The apparatus shall be mounted in a test chamber of sufficient size to permit free circulation of the dust-air mixture around the sample during the test. A mixture of suitable dust and air shall be circulated b
44、y auxiliary equipment and introduced continuously into the test chamber during the entire test period. The particle size of the dust shall be such that it passes through a No. 100 ASTM sieve (approximately 0,15 mm mesh width) with approximately 22 % passing through a No. 200 ASTM sieve (approximatel
45、y 0,075 mm mesh width). b) For the test specified above, the apparatus shall be operated at rated load until maximum temperatures are reached and then disconnected from the supply until it has cooled to approximately room temperature. The number of cycles of heating and cooling shall be at least six
46、 and shall last for a minimum of 30 h. NOTE 1 The maximum temperature under load may be obtained by other means than running at rated load. For an enclosure such as a junction box without any appreciable heating effect (e.g. a switch), the effect of changes in barometric pressure may be simulated to
47、 produce the desired “breathing” effect. NOTE 2 Heating the chamber to 40 C and maintaining this temperature for approximately 1 h and subsequently cooling the chamber to 20 C and maintaining this temperature for 1 h has been found to be a satisfactory method for simulating changes in barometric pre
48、ssure. When the required number of heating and cooling cycles has been completed, the equipment for producing the dust-air atmosphere shall be shut off and the accumulated dust shall be removed from the exterior surfaces of the enclosures by gently brushing, wiping or shaking, with care being taken
49、to avoid the introduction of additional dust into the enclosures. Under no circumstances shall the dust be removed by an air blast or by vacuum cleaning. The enclosure shall then be opened and carefully examined for the degree of dust penetration if any. 8.2.1.4.2 Acceptance criteria No visible dust shall have entered the enclosure. Dust in joints shall not be considered a failure. ANSI/ISA-61241-1 (12.10.03)-2006 (R2011)- 22 - 8.2.1.5 Dust protected apparatus for practice B 8.2.1.5.1 Heat cycling test Proceed as described in 8.2.1.4.1 excep
