1、c I 18 March 1974 MIL- S- 276 24A 12 September 1966 MILITARY SPEC IF ICATLON SWITCH TOGGLE, EXPLOSION- PROOF This specification is approved for use by all Departments and Agencies of the Department of Defense. 1. SCOPE 1.1 This specification covers one type of explosion-proof toggle switch designed
2、for single pole, single throw operation in class 1, groups C and D hazardous locations, as defined by the NFPA No. 70,. National Electrical Code. 2. APPLICABLE DOCUMENTS 2.1 The following documents, of the issue in effect on date of invi- tation for bids or request for proposal, form a part of this
3、specification to the extent specified herein. SPECIFICATION MILITARY MIL-E-17555 - Electronic and Electrical Equipment, Accesso- ries, and Repair Parts, Packaging and Packing of e STANDARDS MILITARY MIL-STD-105 - Sampling Procedures and Tables for Inspection by Attributes. MIL-STD-129 - Marking for
4、Shipment and Storage. MIL-STD-130 - Identification Marking of U,S. Military Property. (Copies of specification and standards required by suppliers in con- nection with specific procurement functions should be obtained from the procuring activity or as directed by the contracting officer.) FSC 5930 P
5、rovided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-3.2 Material. Un1es.s otherwise specified (see 6,2), the material shall be of the quality regularly used
6、by the manufacturer in the product he sells on the commercial market. Material shall be free from all defects and imperfections that might affect the serviceability and appearance of the finished product. 3.3 Design and construction. The design of the switch shall be in accordance with accepted prac
7、tice for this type of equipment. shall consist of a toggle switch, encased in a metallic explosion-proof enclosure which shall be provided with an external operating lever and shall be designed for installation in class 1, groups C.and D hazardous locations, as defined by NFPA No. 70. to insure prop
8、er operation when mounted in any position. modified herein, the switch shall be a regular commercial product of the manufacturer or his suppliers. The parts shall be new and unused. The switch The switch shall be so designed as Except where 3.3.1 Dissimilar metals. The use of dissimilar metals in in
9、timate contact with each other shall be avoided wherever possible in order to minimize galvanic corrosion between these metals. similar metals cannot be avoided, an interposing material which will mini- mize or eliminate this galvanic effect shall be used that would not destroy the UL listing mark.
10、When the use of dis- 3.3.2 Castings. All castings shall be sound and free from patching, misplacedcoring,warping, or any other defect which reduces the castings ability to perform its intended function. 3.3.3 Enclosure, The enclosure shall be of either fabricated or cast metal and shall have provisi
11、on for connection to threaded rigid conduit. An integral conduit stop shall be provided at the inner end of each con- duit opening, or sufficient room shall be provided inside of the enclosure for attachment of a conduit bushing to the protruding end of th.e conduit. The enclosure shall be threaded
12、for use with either 1/2- or 3/4-inch con- duit for dead end or through feed connection as specified (see 6.2), and shall be provided with integral base mounting feet. for actuating the switch shall be installed on the enclosure cover. An operating lever 3.4 Electrical rating. Unless otherwise specif
13、ied (see 6.2), the switch shall be designed for single pole, single throw operation with a standard rating of 20 amperes, 125 volts, tungsten, and also 20 amperes, 250 volts alternating current. 3.5 Fire and casualty hazards. 3.5.1 Each contractor shall submit to the contracting agency, proof that t
14、he switch assembly he proposes to supply under this specification Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-S-27624B conforms to the requirements of UL Standard 894. be accepted as evidence that the switch assembly conforms to this require-
15、 ment. The UL listing mark may 3.5.2 In lieu of the UL listing mark, the bidder may submit independ- ent proof satisfactory to the contracting agency that his switch assembly conforms to the applicable requirements of the published standards includ- ing methods of tests, of UL Standard 20 and UL Sta
16、ndard 894, respectively. 3.5.3 Compliance with the above preliminary requirements in regards to fire and casualty hazards does not absolve the bidder from complete compliance with this specification in order to secure acceptance of his product . 3.6 Identification marking. The switch assembly and pa
17、rts shall be marked for identification in accordance with MIL-STD-130. 4. QUALITY ASSURANCE PROVISIONS 4.1 Responsibility for inspection. Unless otherwise specified in the contract or purchase order, the supplier is responsible for the performance of all inspection requirements as specified herein.
18、Except as otherwise specilied in the contract or order, the supplier may use his own or any other facilities suitable for the performance of inspection requirements specified herein, unless disapproved by the Government, The Government reserves the right to perform any of the inspections set forth i
19、n the specification where such inspections are deemed necessary to assure sup- plies and services conform to prescribed requirements. 4.2 Inspection lot, All switches offered for delivery at one time shall be considered a lot for purposes of inspection. 4.3 Sampling. A random sample of switches shal
20、l be selected from each lot in accordance with MIL-STD-105. 4.3.1 Sampling for examinati0.n. Examination of the switches shall be based on inspection level II and Acceptable Quality Level (AQL) of 1.5 per- cent defective. 4.3.2 S.ampling for tests. Tests of the switches shall be based on inspection
21、level S-2 and an AQL of 1.5 percent defective. 4.4 Examination. Each sample selected in accordance with 4.3.1 shall be examined for compliance with the requirements of this specification and UL Standard 20 and UL Standard 894. encompass all visual examination and dimensional measurements. listing ma
22、rk may be accepted as evidence of the switch assembly conforming to the applicable UL Standard. 4 This element of inspection shall The UL Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-_I MIL-S-27bZLIB 57 77777Ob 0033780 O MIL-S-27624B 4.5 Testing,
23、Each sample selected in accordance with 4.3.2 shall be tested in accordance with applicable tests in UL Standard 20 or UL Stand- ard 894. assembly meeting the tests of the applicable UL Standard. The UL listing mark may be accepted as evidence of the switch 4.6 Preparation for delivery inspection. T
24、he preservation, packag- ing, packing, and marking of the switches shall be inspected to verify conformance to the requirements in section 5. 5. PREPARATION FOR DELIVERY 5.1 Preservation and packaging. The preservation and packaging shall be level A or C, as specified (see 6.2). 5,l.l Level A. The s
25、witches shall be preserved and packaged in accordance with level A of MIL-E-17555. 5.1.2 Level C. The switches shall be preserved and packaged in accordance with the suppliers standard practice. 5.2 Packing. The packing shall be level A, B, or C, as specified (see 6.2). 5.2.1 Level A. The switches s
26、hall be packed in accordance with level A of MIL-E-17555. 5.2.2 Level B. The switches shall be packed in accordance with level B of MIL-E-17555. 5.2.3 Level C. The switches shall be packed in a manner which will Containers and packing shall insure arrival at destination in satisfactory condition and
27、 which will be acceptable to the carrier at lowest rates. comply with Uniform Freight Classification rules or National Motor Freight Classification rules, 5.3 Marking. Interior packages and shipping containers shall be marked in accordance with MIL-STD-129, 6. NOTES 6.1 Intended use. The explosion-p
28、roof toggle switch is intended for use in areas where flammable.gases or vapors exist in quantities sufficient to render the atmosphere explosive or ignitable. 6.2 Ordering data. Procurement documents should specify the follow- ing : (a) Title, number, and date of this specification, (b) Material wh
29、en other than-standard commercial (see 3.2), 5 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-6 *US. GOVERNMENT PRINTING OFFICE: 15 74 - 7 13 - 16 3 /4 6 14 -_ - - _ MIL-S-27bZ4B 57 W 779970b 00319BL 2 i- ML-S-27624B (c) Conduit .size and location r
30、equired (see 3.3.3). (d) When other than standard rating is required (see 3.4). (e) Level of preservation and packaging, and level of packing required (see 5.1 and 5.2). Custodians: Preparing activity: Army - ME Navy - YD Air Force - 11 Project No. 5930-0517 Navy - YD Review activity : Air Force - 80 User activities: Army - AT Navy - SH1 MC Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
