1、Comments, suggestions or questions on this document should be addressed to DLA Land and Maritime ATTN: VAT, Post Office Box 3990, Columbus, OH 43218-3990, or emailed to switchdla.mil. Since contact information can change, you may want to verify the currency of this address information using the ASSI
2、ST Online database at https:/assist.daps.dla.mil/. AMSC N/A FSC 5930 INCH-POUND MIL-DTL-28788C 1 September 2010 SUPERSEDING MIL-DTL-28788B 23 June 2004 DETAIL SPECIFICATION SWITCHES, AIR AND LIQUID FLOW, SENSING, GENERAL SPECIFICATION FOR Inactive for new design after 8 March 1999. This specificatio
3、n is approved for use by all Departments and Agencies of the Department of Defense. 1. SCOPE 1.1 Scope. This specification covers the general requirements for flow switches intended primarily for use in equipment to sense velocity and flow of air or liquid. 1.2 Classification. Switches are classifie
4、d by the flow type, air or liquid, as specified (see 3.1). 2. APPLICABLE DOCUMENTS 2.1 General. The documents listed in this section are specified in sections 3 and 4 of this specification. This section does not include documents cited in other sections of this specification or recommended for addit
5、ional information or as examples. While every effort has been made to ensure the completeness of this list, document users are cautioned that they must meet all specified requirements of documents cited in sections 3 and 4 of this specification, whether or not they are listed. 2.2 Government documen
6、ts. 2.2.1 Specifications, standards, and handbooks. The following specifications, standards, and handbooks form a part of this document to the extent specified herein. Unless otherwise specified, the issues of these documents are those cited in the solicitation or contract. FEDERAL STANDARDS FED-STD
7、-H28A - Screw-Thread Standards for Federal Services COMMERCIAL ITEM DESCRIPTIONS (CIDS) A-A-59588 - Rubber, Silicone Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-DTL-28788C 2 DEPARTMENT OF DEFENSE SPECIFICATIONS MIL-PRF-8516 - Sealing Compound
8、, Synthetic Rubber, Electric Connectors and Electric Systems, Chemically Cured Epoxy. MIL-I-16923 - Insulating Compound, Electrical, Embedding. MIL-PRF-23586 - Sealing Compound, Electrical, Silicone Rubber, with Accelerator. MIL-M-24041 - Molding and Potting Compound, Chemically Cured Polyurethane.
9、MIL-DTL-28786 - Switches, Electrical and Fiver Optic, Packaging of. STANDARDS MIL-STD-202 - Electronic and Electrical Component Parts. MIL-STD-1276 - Leads, Electronic Component Parts MIL-STD-1285 - Marking of Electrical and Electronic Parts (Copies of these documents are available online at https:/
10、assist.daps.dla.mil/quicksearch/ or from the Standardization Document Order Desk, 700 Robbins Avenue, Building 4D, Philadelphia, PA 19111-5094.) 2.3 Non-Government publications. The following documents form a part of this document to the extent specified herein. Unless otherwise specified, the issue
11、s of these documents are those cited in the solicitation or contract. AMERICAN NATIONAL STANDARDS INSTITUTE (ANSI) ANSI/NCSL-Z540.3 - Calibration Laboratories and Measuring and Test Equipment-General Requirements. (Application for copies can be found online at http:/www.ansi.org/ or 25 West 43rd Str
12、eet, New York, NY 10036-8002, telephone 212-642-4900, fax 212-302-1286) AMERICAN SOCIETY FOR TESTING AND MATERIAL (ASTM) ASTM-D5948 - Compounds, Molding, Thermosetting ASTM-G21 - Materials to Fungi, Synthetic Polymeric, Determining Resistance of (Application for copies can be found online at http:/w
13、ww.astm.org/ or should be addressed to the American Society for Testing and Materials, 100 Barr Harbor Drive, P.O.Box C700, West Conshohocken, PA, 19428-2959). INTERNATIONAL ORGINATIONS FOR STANDARDS (ISO) ISO 10012-1 - Quality Assurance Requirements for Measuring Equipment - Part 1: Metrological Co
14、nfirmation System for Measuring Equipment. (Application for copies can be found online at http:/www.ansi.org/ or 25 West 43rd Street, New York, NY 10036-8002, telephone 212-642-4900, fax 212-302-1286) Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-M
15、IL-DTL-28788C 3 SOCIETY OF AUTOMOTIVE ENGINEERS SAE-AMS-I-10 - Insulation Compound, Electrical, Ceramic, Class L SAE-AS81550 - Insulating Compound, Electrical, Embedding, Reversion Resistant Silicone. (Application for copies can be found online at http:/www.sae.org or should be addressed to the Soci
16、ety Of Automotive Engineers (SAE) World Headquarters, 400 commonwealth Drive, Warrendale, PA 15096-0001) 2.4 Order of precedence. Unless otherwise noted herein or in the contract, in the event of a conflict between the text of this document and the references cited herein (except for related specifi
17、cation sheets), the text of this document takes precedence. Nothing in this document, however, supersedes applicable laws and regulations unless a specific exemption has been obtained. 3. REQUIREMENTS 3.1 Specification sheets. The individual item requirements shall be as specified herein and in acco
18、rdance with the applicable specification sheets. In the event of any conflict between requirements of this specification and the specification sheet, the latter shall govern (see 6.1). 3.2 Switch categories. Switches furnished under this specification shall be category I or II as defined herein. 3.2
19、.1 Category I. Switches completely defined by a military specification sheet. 3.2.2 Category II. Switches the same as category I, except for minor differences such as terminations, mounting means, or flow settings, which do not change the basic design or construction of the qualified switch. Categor
20、y II shall be procured from a source listed on the applicable qualified products list for the particular similar product in category I. Category II switches are nonstandard. 3.3 Qualification. Category I switches furnished under this specification shall be products which are qualified for listing on
21、 the applicable qualified products list at the time set for opening of bids (see 4.5 and 6.2). 3.4 Material. Material shall be as specified herein. However, when a definite material is not specified, a material shall be used which will enable the switches to meet the performance requirements of this
22、 specification. Acceptance or approval of any constituent material shall not be construed as a guaranty of the acceptance of the finished product. 3.4.1 Metals. All metal parts exposed to environmental conditions shall be of a corrosion-resistant material or shall be suitably plated to resist corros
23、ion. 3.4.1.1 Ferrous material. Ferrous material shall not be used for current-carrying parts except for feed-through terminals in headers. 3.4.1.2 Dissimilar metals. When dissimilar metals are used in intimate contact with each other, protection against electrolysis and corrosion shall be provided.
24、The use of dissimilar metals in contact, which tend toward active electrolytic corrosion (particularly brass, copper, or steel used in contact with aluminum or aluminum alloy), it is not acceptable. However, metal-spraying or metal plating of dissimilar base metals to provide similar or suitable abu
25、tting surfaces is permitted. The use of dissimilar metals separated by a suitable insulating material is also permitted. 3.4.1.3 Pure tin. The use of pure tin, as an underplate or final finish, is prohibited both internally and externally. Tin content of switch components and solder shall not exceed
26、 97 percent, by mass. Tin shall be alloyed with a minimum of 3 percent lead, by mass (see 6.6) Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-DTL-28788C 4 3.4.2 Insulation. 3.4.2.1 Plastic. Unless otherwise specified (see 3.1 and 6.2), molded pl
27、astic material shall conform to ASTM-D5948, except that cotton-, wood-, or cellulose-filled molding materials shall not be used. 3.4.2.1.1 Thermoplastics. Thermoplastics shall not be used. 3.4.2.2 Ceramic. Ceramic insulation shall used which will enable the switch to meet the performance requirement
28、s of this specification. 3.4.3 Rubber. Rubber parts except media seals shall be in accordance with A-A-59588. 3.4.4 Weldability. Leads designed for weldability shall conform to requirements of MIL-STD-1276, type K. 3.4.5 Potting compounds. Unless otherwise specified (see 3.1), potting compounds shal
29、l be in accordance with MIL-PRF-8516, MIL-PRF-23586, SAE-AS81550, MIL-M-24041, or MIL-I-16923 within their specified temperature ranges. 3.4.6 Fungus resistant material. Unless certification is furnished, materials for fabrication of switches covered by this specification shall conform to requiremen
30、t 4 of ASTM-G21. When nutrient materials are used, they shall be treated prior to fabrication of the switches. 3.5 Design and construction. Switches shall be of the design, construction, and physical dimensions specified (see 3.1), and shall be so constructed as to ensure proper operation when mount
31、ed in any position. The electrical ratings shall be as specified (see 3.1 and 6.1). 3.5.1 Mounting. Mounting shall be as specified (see 3.1 and 6.1). Stud mounting shall have threads in accordance with FED-STD-H28. 3.5.2 Termination. Termination shall be as specified (see 3.1). 3.5.2.1 Solder termin
32、als. Solder terminals shall be treated to facilitate soldering. The terminal design shall be such that a mechanical connection can be made prior to soldering. Acceptable solder terminal designs are turret, hook, pierced, or post type. Gold plating shall not be used. 3.5.2.2 Screw terminals. Screw te
33、rminals shall be provided with hardware as specified (see 3.1 and 6.2). Lockwashers shall be captive to the screw. For direct Government orders, all terminal hardware shall be assembled in proper order. 3.5.3 Screw threads. Screw threads on removable threaded parts shall be in accordance with unifie
34、d thread series of FED-STD-H28. Threading of nonmetallic parts shall not be permitted. Terminal threading engagement shall be at least two full threads. 3.5.4 Tamperproof calibration. Unless otherwise specified (see 3.1 and 6.2), the switches shall be so sealed that any tampering with the calibratio
35、n after final adjustment by the manufacturer shall require dismantling of the switch or the breaking of a seal. The seal shall not be easily broken by manual force or without the use of any device considered a tool, that is, screwdriver, pliers, soldering iron, and so forth. 3.5.5 Weight. Weight sha
36、ll be as specified (see 3.1 and 6.2). 3.5.6 Actuating mechanism. The external actuator shall be insulated from all current-carrying parts. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-DTL-28788C 5 3.6 Solderability (when specified, see 3.1). W
37、hen switches are tested as specified in 4.7.2, 95 percent of the total length of fillet, which is between the standard wrap wire and the terminal, shall be tangent to the surface of the terminal being tested. There shall be no pinholes, voids, and so forth. A ragged or interrupted line at the point
38、of tangency between the fillet and the terminal under test shall be considered a defect. After the test, there shall be no evidence of fracture, loosening of parts, or any other mechanical failure of the switches. 3.7 Run-in (when specified, see 3.1 and 6.1). When switches are tested as specified in
39、 4.7.3, the operating points shall be within the tolerances specified (see 3.1). 3.8 Calibration (see 3.1 and 6.1). 3.8.1 Actuation and deactuation. When tested as specified in 4.7.4.1, switches shall actuate and deactuate at the flow rate and pressure specified (see 3.1 and 6.1). 3.8.2 Proof flow.
40、When tested as specified in 4.7.4.2, switches shall be capable of passing a minimum proof flow with a maximum differential pressure (pressure drop) as specified (see 3.1 and 6.1). 3.8.3 Differential pressure (pressure drop through switches). When tested as specified in 4.7.4.3, calibration and proof
41、 flow, the total pressure drop across the switch shall not exceed the specified values (see 3.1 and 6.1). 3.8.4 Proof pressure. When tested as specified in 4.7.4.4, switches shall show no evidence of leakage. Unless otherwise specified (see 3.1), the proof pressure shall be at least 150 percent of t
42、he maximum operating pressure. The actuation and deactuation flow rate, measured before and after the proof pressure test, shall not differ by more than the tolerances specified (see 3.1 and 6.1). 3.9 Transfer time. When switches are tested as specified in 4.7.5, the contacts of a pole shall transfe
43、r within 5 milliseconds on both increasing and decreasing flow within the operating tolerances specified (see 3.1 and 6.1). 3.10 Coincidence of operating points (applicable to multipole switches only). When switches are tested as specified in 4.7.6, all poles shall transfer within a total operating
44、time of 10 milliseconds on both increasing and decreasing flow within the operating tolerances specified (see 3.1 and 6.1). 3.11 High temperature. When switches are tested as specified in 4.7.7, there shall be no evidence of malfunction, internal leakage, deterioration, combustion, or any other dama
45、ge that may adversely affect the operation of the switch. 3.12 Low temperature. When switches are tested as specified in 4.7.8, there shall be no evidence of malfunction, internal leakage, deterioration, combustion, or any other damage that may adversely affect the operation of the switch. 3.13 Term
46、inal strength (when specified, see 3.1). When switches are tested as specified in 4.7.9, the terminals shall not break, loosen, crack, or affect the operation of the switch. 3.14 Connector torque (when specified, see 3.1). When switches are tested as specified in 4.7.10, there shall be no loosening,
47、 rotation, distention, short circuiting, open circuiting, or other damage of any portion of the connector-switch interface or switch itself. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-DTL-28788C 6 3.15 Shock. Unless otherwise specified (see
48、3.1 and 6.1), when switches are tested as specified in 4.7.11, there shall be no change in operation, no evidence of broken, deformed, displace, or loose parts, and the operating points shall be within the tolerances specified (see 3.1). 3.15.1 Method I (shock, specified pulse). When switches are te
49、sted as specified in 4.7.11.1, closing of open contacts and chatter of closed contacts shall not exceed 10 microseconds, unless otherwise specified (see 3.1 and 6.1). 3.15.2 Method II (when specified, see 3.1) (high-impact shock). When switches are tested as specified in 4.7.11.2, closing of open contacts and chatter of closed contacts shall not exceed 20 milliseconds, unless otherwise specified (see 3.1 and 6.2). 3.16 Vibration. When switches
