1、KSC-S-126B OCTOBER 29, 2008 Supersedes KSC-S-126A December 7, 1990 METRIC National Aeronautics and Space Administration John F. Kennedy Space Center KSC FORM 16-12 (REV. 6/95) PREVIOUS EDITIONS ARE OBSOLETE (CG 11/95) SEALING OF ELECTRICAL COMPONENTS, SPECIFICATION FOR EAR 99 NO LICENSE REQUIRED The
2、 information contained in the document is technical in content, but not technical data as defined by the ITAR or the EAR and therefore is EAR 99 NLR; no export license required. (General Prohibition Six (Embargo) applies to all items subject to the EAR, i.e. items on the CCL and within EAR 99 NLR. Y
3、ou may not make an export or re-export contrary to the provi-sions of part 746 (Embargos and Other Special Controls) of the EAR and 22 CFR part 126.1 of the ITAR.) EDDS #8571 ENGINEERING DIRECTORATEProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Prov
4、ided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-METRICKSC-S-126BOCTOBER 29, 2008SupersedesKSC-S-126ADecember 7, 1990SEALING OF ELECTRICAL COMPONENTS,SPECIFICATION FORApproved by:6?rPatrick A. Simpkins, D.BADirector, Engineering DirectorateJOHN F. KENNEDY
5、 SPACE CENTER, NASAProvided 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-,-,-KSC-S-126B October 29, 2008 CONTENTS 1. SCOPE .1 1.1 Introduction1 1.2 Classification
6、1 1.2.1 Grade A1 1.2.2 Grade B 1 1.2.3 Grade C 1 1.2.4 Grade D2 2. APPLICABLE DOCUMENTS .2 2.1 Governmental.2 2.2 Non-Governmental 2 3. REQUIREMENTS.3 3.1 Leakage Rates 3 3.1.1 Grade A Seal3 3.1.2 Grade B Seal 3 3.1.3 Grade C Seal 3 3.1.4 Grade D Seal3 3.2 Environmental Test Requirements.3 3.2.1 Hig
7、h-Temperature Test4 3.2.2 Temperature Shock Test 4 3.2.3 Vibration Test 4 3.2.4 Shock Test4 3.2.5 Salt Fog Test 5 3.2.6 Explosion Test .5 3.2.7 Solar Radiation.5 4. QUALITY ASSURANCE PROVISIONS 5 4.1 Leakage Measurement .5 4.2 Environmental Tests 6 4.2.1 High-Temperature Test6 4.2.1.1 Procedure .6 4
8、.2.1.2 Measurements 6 4.2.2 Temperature Shock Test 6 4.2.2.1 Procedure .6 4.2.2.2 Measurements 6 4.2.3 Vibration Test 6 4.2.3.1 Procedure .6 4.2.3.2 Measurements 7 4.2.4 Shock Test7 4.2.4.1 Procedure .7 4.2.4.2 Measurements 7 KSC-S-126B_DD_10292008.doc iii Provided by IHSNot for ResaleNo reproductio
9、n or networking permitted without license from IHS-,-,-KSC-S-126B October 29, 2008 4.2.5 Salt Fog Test 7 4.2.5.1 Procedure .7 4.2.5.2 Measurements 7 4.2.6 Explosion Test .7 4.2.7 Solar Radiation.7 4.2.7.1 Procedure .7 4.2.7.2 Measurements 8 5. PREPARATION FOR DELIVERY 8 6. INTENDED USE.8 TABLES Tabl
10、e 1. Required Test Sequence.4 Table 2. Leakage Rates 6 iv Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-KSC-S-126B October 29, 2008 ABBREVIATIONS, ACRONYMS, AND SYMBOLS C degree Celsius ASTM American Society for Testing and Materials cm centimeter
11、KSC Kennedy Space Center NASA National Aeronautics and Space Administration NEMA National Electrical Manufacturers Association s second v Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-KSC-S-126B October 29, 2008 This page intentionally left blank.
12、vi Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-KSC-S-126B October 29, 2008 SEALING OF ELECTRICAL COMPONENTS, SPECIFICATION FOR 1. SCOPE 1.1 Introduction This specification defines four grades of seals for noncryogenic use in the design of electri
13、cal components and their assemblies, containers, and equipment used in ground support equipment at the John F. Kennedy Space Center (KSC). The requirements specified herein are not applica-ble to the National Electrical Manufacturers Association (NEMA) electrical enclosures. 1.2 Classification Seals
14、 shall be classified as described in the following subsections. 1.2.1 Grade A A Grade A seal is (1) metal-to-metal (welded, brazed, or soldered joints), (2) metal-to-glass, or (3) ceramic (brazed or solder joints). A Grade A seal is accomplished by the bonding of metallic and ceramic materials or a
15、combination of the two. This includes the bonding of metals by weld-ing, brazing, or soldering; the fusion of ceramic materials under heat or pressure; and the fusion of ceramic materials into a metallic support. 1.2.2 Grade B A Grade B seal is accomplished by fusion, vulcanization, or adhesion to t
16、he metallic case, using a chemical or mechanical process (or combination of the two), with any material such as thermo-setting plastics or elastomers (e.g., polytetrafluoroethylene, polychlorotrifluoroethyene, and sili-cones). A Grade B seal can be accomplished by encapsulating, molding, or potting
17、a component or assembly with a plastic or elastomer. 1.2.3 Grade C A Grade C seal is a gasket-type seal. The seal is accomplished using gaskets, O-rings, or other similar items held in proper relation to the abutting surface by pressure exerted by screws, bolts, or other clamping devices. CAUTION Wh
18、ere Grade B or Grade C seals are specified, consult the responsible design organization for information about environmental conditions, such as sun rays, radioactivity, and hazardous liquids or vapors, that could cause deteriorate the seals. 1 Provided by IHSNot for ResaleNo reproduction or networki
19、ng permitted without license from IHS-,-,-KSC-S-126B October 29, 2008 1.2.4 Grade D A Grade D seal is a ground, lapped, or polished abutting-surface seal. The seal is accomplished by grinding, lapping, or polishing the abutting surface to produce a precise fit. The mating sur-faces are held in intim
20、ate contact by bolts, screws, or other suitable clamping devices. 2. APPLICABLE DOCUMENTS The following documents form a part of this specification to the extent specified herein. When this specification is used for procurement, including solicitations, or is added to an existing con-tract, the spec
21、ific revision levels, amendments, and approval dates of said documents shall be specified in an attachment to the Solicitation/Statement of Work/Contract. 2.1 Governmental John F. Kennedy Space Center (KSC), NASA KSC-STD-164 Environmental Test Methods for Ground Support Equipment, Standard for (Copi
22、es of specifications, standards, drawings, and publications required by suppliers in connec-tion with specified procurement functions should be obtained from the procuring activity or as directed by the Contracting Officer.) 2.2 Non-Governmental American Society for Testing and Materials (ASTM) ASTM
23、 E 493 Standard Test Methods for Leaks Using the Mass Spectrometer Leak Detector in the Inside-Out Test-ing Mode ASTM E 498 Standard Test Methods for Leaks Using the Mass Spectrometer Leak Detector or Residual Gas Ana-lyzer in the Tracer Probe Mode ASTM E 499 Standard Test Methods for Leaks Using th
24、e Mass Spectrometer Leak Detector in the Detector Probe Mode 2 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-KSC-S-126B October 29, 2008 3. REQUIREMENTS 3.1 Leakage Rates Drawings and specifications that include seals shall specify (1) the grade of
25、 seal required and (2) the total permissible leakage rate. When the total permissible leakage rate is not specified, the rate shall be determined on the basis of seal length as specified by the grade definition. Seals shall comply with the leakage limits both before and after the environmental tests
26、 required by the respective grade of seals specified herein. 3.1.1 Grade A Seal At a pressure differential of 1 atmosphere, a Grade A seal shall have a leakage rate not to exceed 1.25 108cubic centimeters per second (cm3/s) of air per centimeter of seal. 3.1.2 Grade B Seal At a pressure differential
27、 of 1 atmosphere, a Grade B seal shall have a leakage rate not to exceed 1.25 106cm3/s of air per centimeter of seal. 3.1.3 Grade C Seal At a pressure differential of 1 atmosphere, a Grade C seal shall have a leakage rate not to exceed 1.25 104cm3/s of air per centimeter of seal. 3.1.4 Grade D Seal
28、At a pressure differential of 1 atmosphere, a Grade D seal shall have a leakage rate not to exceed 1.25 103cm3/s of air per centimeter of seal. 3.2 Environmental Test Requirements Unless otherwise specified, the environmental tests and sequence for the grade of seals specified herein shall be in acc
29、ordance with Table 1. Leakage shall be measured before and after each en-vironmental test, in accordance with 4.1. Additional leakage measurements shall be made when included as a part of the respective test instruction. 3 Provided by IHSNot for ResaleNo reproduction or networking permitted without
30、license from IHS-,-,-KSC-S-126B October 29, 2008 Table 1. Required Test Sequence Seal Grade Environmental Test Sequence A B C D 1. High temperature X X X X 2. Temperature shock X X X 3. Vibration X X X X 4. Shock X X X X 5. Salt fog X X X X 6. Explosion X 7. Solar radiation X X X X 3.2.1 High-Temper
31、ature Test The seals shall be subjected to the high-temperature test for the respective class, as specified in 4.2.1, to determine the capability of the seals to withstand exposure to the extremes of high tem-peratures for extended periods. The seal temperature classes are defined as follows: a. Cla
32、ss I applies to those seals that are exposed to direct solar radiation or confined in an enclosure exposed to solar radiation. b. Class II applies to seals that are neither exposed to direct solar radiation nor con-fined in an enclosure exposed to solar radiation. 3.2.2 Temperature Shock Test All se
33、als fabricated with glass, ceramic, or other electrical insulating materials shall be subjected to the temperature shock test as specified in 4.2.2, to determine the capability of the seals to withstand rapid changes in temperature without cracking or flaking. The temperature shock test shall be per
34、formed following the high-temperature test. 3.2.3 Vibration Test Seals shall be subjected to the vibration test, as specified in 4.2.3, for the purposes of (1) deter-mining the effects of vibration on the seals and (2) detecting any mechanical damage from vibra-tion that would allow leakage through
35、cracked seams or cracked ceramic or terminal seals. 3.2.4 Shock Test Seals shall be subjected to the shock test, as specified in 4.2.4, for the purposes of (1) determin-ing the effects of shock on the seals and (2) detecting any mechanical damage that would allow leakage through cracked seams or cra
36、cked ceramic or terminal seals. 4 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-KSC-S-126B October 29, 2008 3.2.5 Salt Fog Test Seals shall be subjected to the salt fog test, as specified in 4.2.5, for the purpose of determining the capability of t
37、he seals to withstand exposure to such conditions. 3.2.6 Explosion Test Grade A seals shall be subjected to the explosion test, as specified in 4.2.6, for the purpose of determining the capability of the seals to provide ignitionproof protection when exposed to ex-plosive environments. Grades B, C,
38、and D seals shall be subjected to an explosion test only when directed by the responsible design organization. 3.2.7 Solar Radiation Seals that are exposed to direct radiation shall be subjected to the solar radiation test, as specified in 4.2.7, for the purpose of determining the capability of the
39、seal to withstand sunlight and per-form its sealing function. 4. QUALITY ASSURANCE PROVISIONS Leakage tests and detection methods shall be submitted to the responsible design organization for approval in accordance with the provisions of the contract. Except as otherwise specified, en-vironmental te
40、sts shall be conducted in accordance with KSC-STD-164. Inspection and test re-cords shall be kept complete and, upon request, made available to the procuring organization. 4.1 Leakage Measurement Leakage for all grades of seals shall be measured by the use of helium mass spectrometer leak detector m
41、ethods specified in one of the following: ASTM E 493, ASTM E 498, or ASTM E 499. Breaking of seals to facilitate leakage measurement method shall be avoided. At 25 degrees Celsius (C), the leakage measurement for all seals shall be made with 1 atmosphere of pressure (759.999 micrometers of mercury)
42、on one side of the seal and a vacuum in the order of 1 micrometer of mercury on the other side (or any combination netting a pressure differential equal to 1 atmosphere from one side of the seal to the other). Table 2 lists the permissible leak-age rates of various gases relative to air. The pressur
43、e differential shall be applied in the direction that would be seen in actual usage. The failure mode of the seal shall also be considered in ap-plying the pressure differential. 5 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-KSC-S-126B October 29
44、, 2008 Table 2. Leakage Rates Gas Leakage Rate Relative to Air (Percent) Helium 0.91 Hydrogen 2.0 Oxygen 0.863 Water vapor 1.82 Nitrogen 1.04 4.2 Environmental Tests 4.2.1 High-Temperature Test 4.2.1.1 Procedure The test specimen shall be placed within the test chamber and subjected to the applicabl
45、e tem-perature cycles shown in KSC-STD-164 for a total of five cycles. The test requirements, specifi-cations, procedures, and documentation shall be in accordance with KSC-STD-164. 4.2.1.2 Measurements Following the temperature test, leakage shall be measured as specified in 4.1. The leakage rate s
46、hall not exceed the limits specified in 3.1 for each grade of seals. 4.2.2 Temperature Shock Test 4.2.2.1 Procedure The test specimen shall be placed within a test chamber at the temperatures specified in KSC-STD-164 for a total of five cycles. The test requirements, specifications, procedures, and
47、documentation shall be in accordance with KSC-STD-164. 4.2.2.2 Measurements Following the temperature shock test, leakage shall be measured as specified in 4.1. The leakage rate shall not exceed the limits specified in 3.1 for each grade of seals. 4.2.3 Vibration Test 4.2.3.1 Procedure Vibration tes
48、t requirements, specifications, procedures, verification of test input, and documenta-tion shall be in accordance with KSC-STD-164. 6 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-KSC-S-126B October 29, 2008 4.2.3.2 Measurements Following the vibration test, leakage shall be measured as specified in 4.1. The leakage rate shall not exceed the limits specified in 3.1 for each grade of seals. 4.2.4 Shock Test
