1、- o mIL-I-25437B 66 = 777770b 04235bb O W MIL-1-25437B( USAF) g,. .- 3 October 1984 CY SUPERSEDING . MIL-I-25437A( USAF) 1 Beneficial comments (recommendations, additions, deletions) and any pertinent data which may be of use in improving this document should be addressed to: ASDIENES, Wright-Patter
2、son AFB, OH 45433 by using the self-addressed Standardization Document Improvement Proposal (DD Form 1426) appearing at the end of this document or by letter. 14 November 1967 MILITARY SPECIFICATION INDICATORS, AIRCRAFT, PRESSURE, VOLTAGE RATTO TYPE, GENERAL SPECIFICATION FOR This specification is a
3、pproved for use by the Department Departments and Agencies of the Department of Defense of the Air Force, and is available for use by all 1. SCOPE 1.1 pressure indicators that operate on alternating current. This specification covers the general requirements for voltage ratio type 2. APPLICABLE DOCU
4、MENTS 2.1 Government documents 2.1.1 SDecification and standards. Unless otherwise specified, the fol- lowing specifications and standards of the issue listed in that issue of the Department of Defense Index of Specifications and Standards (DODISS) specified in the solicitation form a part of this s
5、pecification to the extent specified herein. SPECIFICATIONS FEDERAL PPP-E-60 1 Boxes, Wood, Cleated Plywood PPP-B-6 36 Box, Fiberboard MILITARY MIL-P-1 16 Preservation-packaging, Methods of MIL-C-50 15 Connectors, Electrical, Circular Threaded, AN-Type, General Specification For MIL-(3-5541 Chemical
6、 Conversion Coatings on Aluminum and Aluminum Alloys MIL-S-7742 Screw Threads, Standard, Optimum Selected Series: General Specification for MIL-A-8625 Anodic Coatings, For Aluminuin and Aluminum Alloys MIL-T- 25435 Transmitters, Pressure, Aircraft, Variable, Reluctance Type, General Specification Fo
7、r FSC 6685 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-1-254376 bb W 777770b 04235b7 2 M MIL-1-254 37 B ( USAF ) STANDARDS DOD-STD-100 MIL-STD-129 MIL-STD-130 MIL-STD-143 t4IL-STO-8 1 O MIL-STD-889 MIL-STD-1186 MS 33558 MS 33638 MS 33639 MS 3
8、3678 Engineering Drawing Practice Marking for Shipment and Storage Identification Marking of US Military Property Standards and Specifications, Order of Precedence for the Selection Of Environmental Test Methods and Engineering Guidelines Dissimilar Metals Cushioning, Anchoring, Bracing, Blocking, a
9、nd Waterproofing, With Appropriate Test Methods Numerals and Letters, Aircraft Instrument Dial, Standard Form Of Case, Instrument, Flange-Mounted, Aircraft Case, Instrument, Clamp-Mounted, Aircraft. Connector, Receptable, Electric, Integral Mounting (Copies of specifications and standards required b
10、y manufacturers in connection with specific aoquisition functions should be obtained from the contracting aotivity or as directed by the contracting officer.) 2.2 Other Dublicationl. The following document forms a part of this specification to the extent specified herein. UNIFORM CLASSIFICATION COMM
11、ITTEE, AGENT RULER Uniform Freight Classifiction (Application for copies should be addressed to Uniform Classification Committee, Room 1106, 222 South Riverside Plaza, Chicago, IL 60606.) 2.3 Order of Precedence. specification and the references cited herein, the text of this specification shall tak
12、e precedence. In the event of a conflict between the text of this 3. REQUIREMENTS 3.1 TvPe of Pre-DrOdUCtiOn testinq. The type of pre-production testing (qualification or first article) to be accomplished on indicators shall be as specified in the detail specification. 3.2 selection of specification
13、s and standards. Specifications and standards for necessary commodities and services not specified herein shall be selected in accordance with MIL-STD-143. 3.3 Materiala 3.3.1 N9nmannetio materials. Nonmagnetic materials shall be used for all parts of the indicator except where magnetic materials ar
14、e essential. 3.3.2 Nonferrous materials. of the indicator except where ferrous materials are essential. Nonferrous materials shall be used for all parts 2 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-1-254378 66 W 777770b 0333370 7 W MIL- I-25
15、4378( USAF) 3.3.3 Metah. Metals shall be of the corrosion-resistant type or suitably treated to resist corrosion due to fuels, salt fog, or atmospheric conditions likely to be met in storage or normal service. 3.3.4 Dissimilar metalg. Unless suitably protected against electrolytic corrosions, dissim
16、llar metals shall not be used in intimate contact with each other. Dissimilar metals are defined in MIL-STD-889. 3 3.3.5 the first before, and the second after the instrument is tapped. difference between the first and second readings shall not exceed the friction bolerance specified in the detail s
17、pecification. The second reading shall not Examination of product, The indicator shall be inspected to determine Prior to assembly, dials and pointers shall be A potential of 200V rms at a comercial frequency If the design of the There shall Two readings shall be The exceed the scale error specified
18、 in the detail specification. 4.5.4 Position error. The standard transformer shall be adjusted to provide a voltage across pins i3 and C corresponding to the pressure specified in the detail specification. The reading of the indicator taken while the indicator is in a normal upright position shall n
19、ot differ fron the reading while the indicator is held in any other position by more than the amount specified in the detail specification. 12 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-I-25q37B bb m 333740b 0423576 3 m MIL-I-25437B(USAF) 1
20、4.5.5 Sealinq. When a nitrogen-heliun mixture is used as the filling medium, a mass spectrometer-type of helium leak detector shall be used to test for leakage. The leak rate shall not exceed 0.1 micron cubic foot per hour, When helium is not used as a part of the filling medium, the indicator shall
21、 be immersed in deaerated distilled water treated by adding approximately 0.1 percent by weight of alkyl-aryl-sodium-sulfonate type wetting agent (40 percent active ingredient), reduced to approximately 2-1/2 inches Hg. Any bubbles coming from within the instrument case shall be considered leakage a
22、nd shall be cause for rejection. Bubbles which are the result of entrapped air on the exterior surfaces of the case shall not be considered as leakage. The absolute pressure of the air above the water shall be 4.5.6 Vibration. accordance with MIL-STD-810, method 514.3, equipment category I, except t
23、hat curve A shall apply, provide voltages corresponding to an indication of approximately midscale on the indicator. Pointer oscillation shall not exceed 5 percent double amplf- tude. Upon completion of this test, the indicator shall be subjected to the scale error test at room temperature. The scal
24、e errors shall not exceed the tolerances specified in the detail specification. The indicator shall be subjected to a vibration test in A standard transmitter circuit shall be adjusted to 4.5.7 Low temoerature. The indicator shall be subjected to a temperature of -54OC 22OC for 2 period of 4 hours.
25、While at this temperature, the indicator aka11 be tested for scale error and friction as specified in 4.5.3, except in every case, the indicator shall not require more than 5 seconds to come within the specified tolerances. Scale error and friction tolerances shall not exceed the values specified in
26、 the detail specification. 4.5.8 HiRh temDerature. The indicator shall be subjected to a temperature of 71% :Soc for a period of 4 hours. shall be tested for scale error and friction as specified in 4.5.3. The scale error and friction tolerances shall not exceed the values specified in the detail sp
27、ecification. 0 While at this temperature, the indicator 4.5.9 Fonninq, perature of 85% 25OC for a minimum period of 2 hours. removal from the oven, the indicator shall be immersed to a depth of 1/4 inch in an ice water bath maintained at 0% to 7OC. shall be removed from the fluid bath and quickly wi
28、ped dry (compressed air shall not be used). and any evidence of fogging or damage shall be cause for rejection. The indicator shall be placed in a controlled ambient tem- Within O seconds after After 3 minutes, the indicator The cover glass and dial shall immediately be inspected 4.5.10 Electrical c
29、haracteristics. The indicator electrical characteristics shall be checked to determine compliance with 3.5.6 through 3.5.6.3. 4.5.11 MaRnetiC effect. The indicator, first, not operating and second, operating on rated voltage, shall be rotated in a vertical plane about a short bar magnetic compass wi
30、th the nearest path of the indicator 5-1/2 inches from and magnetically East or West of the center of the compass. Starting directly under the compass, the indicator shall be held in positions O, 45O, goop 135O, 180, 225O, 270, and 315O from the initial position. At each of these positions, the indi
31、cator shall be rotated on its own horizontal axis until it is in its normal upright position. shall be 0.17 to 0.19 oersted. Deflections of the compass at any of the specified positions shall not exceed lo. The horizontal magnetic field intensity 0 13 Provided by IHSNot for ResaleNo reproduction or
32、networking permitted without license from IHS-,-,-MIL-1-254378 bb 777970b 0423577 5 b MIL- I-254378( USAF ) I 4.5.12 Effect of lead lennth. The indicator shall not change more than 1 psi when the lead length between the indicator and transmitter is changed from 5 to 300 feet of No, 20 AWG gage wire,
33、 Equivalent resistances may be substituted for the added wire length. 4.5.13 TemDerature-altitude, The temperature-altitude test shall be conducted in accordance with MIL-STD-810, method 520, procedure III (except the temper- ature shall be -55OC) with a chamber pressure equivalent to an altitude of
34、 100,000 feet. The rate of pressure change in the chamber shall not; exceed an average of 3 psi per second while under these conditions and at the end of a 1-hour period, the scale error and friction test shall be conducted. The errors shall not exceed the tolerances specified in the detail specific
35、ation. This test may be conducted concurrently with the low temperature exposure test. 4.5.14 Low temperature exDosure. The indicator shall be subjected to a temperature of -65OC 22OC for a period of 48 hours. the indicator shall be operted to assure that the pointer moves over the entire scale rang
36、e without exhibiting sticky or erratic characteristics, temperature shall then be raised to -55OC f2OC and held for a period of 24 hours. While at this temperature, the indicator shall be subjected to the scale error and friction test, except that in every case, the indicator shall not require more
37、than 5 seconds to come within the tolerances specified in the detail specification. All parts of the indicator shall be maintained at room temperature for a period of not less than 1 hour and then subjected to the scale error at room teniperature test specified in the detail specification. The scale
38、 errors shall not exceed the tolerances specified therein and no damage or deterioration shall have occurred that would affect subsequent operation. While at this temperature, The 4.5.15 HiRh tetuDerature exoosure. The indicator shall be subjected to a temperature of 7OOC 12OC for a period of 24 hou
39、rs. The indicator shall then be tested at this temperature for scale errors as specified in 4.5.3. scale error and friction tolerances shall not exceed the values specified in the detail specification. All parts of the indicator shall then be maintained at room temperature for a period of not less t
40、han 1 hour and the indicator subjected to the scale error at room temperature test specified in the detail specification. The scale errors observed shall not exceed the tolerances specified therein and no damage or deterioration shall have occurred that would affect subsequent operation. The 4.5.16
41、Thermal shock. immersion in water at a temperature of 85OC 22OC and then in water at a tempe- rature of 5OC 2OC without evidence of moisture penetration or damage to the coating or the case. The length of time for each immersion shall be 30 ninutes, with not more than 5 seconds between immersions, A
42、fter eight con- tinuous cycles have been completed, the indicator shall be subjected to the test specified in 4.5.5. No leakage shall occur as a result of this test. The indicator shall be subjected to eight cycles of 4.5.17 Salt fog. accordance with MIL-STD-810, method 509.2, for a period of 48 hou
43、rs and then examined. There shall be no evidence of external corrosion of deterioration that would affect subsequent operation. The indicator shall be subjected to the test specified in 4.5.2. 20 megohms, The scale errors shall not exceed the tolerances specified in the detail specification. The ind
44、icator shall be subjected to a salt fog test in The measured resistance shall be a minimum of The indicator shall then be subjected to the scale error test. 14 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-I-254378 bb 99997b 0423578 7 MIL-I-254
45、37B(USAF) 2 4.5.18 DamDinq. The indicator pointer shall be positioned at approximately O-psi pressure. With excitation power off, the test transmitter shall be positioned to the equivalent of 60 psi. Excitation power shall then be applied and the time for the indicator to indicate 60 psi shall not e
46、xceed 2.0 seconds. The pointer shall move smoothly, shall not oscillate, and shall not overshoot more than two times. 4.6 Insoeotion of DaCkaKinq. The sampling and inspection of the preservation, packing, and container marking shall be in accordance with the requirements of section 5. 5. PACKAGING 5
47、.1 Preservation and DaCkaRinR, Preservation and packaging shall be level A or C, as specified (see 6.2). 5.1.1 Level A. Unless otherwise specified in the contract or order, indi- cators shall be individually preserved and packaged in accordance with MIL- P-116, method III, and placed in a snug-fitti
48、ng unit container conforming to PPP-B-636. 5.1.2 Level C. Indicators shall be individually preserved and packaged in a manner that will afford adequate protection against corrosion, deterioration, or physical damage during shipment from the supply source to the first re- ceiving activity. provided t
49、he latter meets the requirements of this level. This level may conform to the suppliers standard practice 5.2 PackinR. Packing shall be level A, B or C, as specified (see 6.2). 5.2.1 Level A. Indicators preserved and packaged as specified in 5.1.1 shall be packed in weather-resistant shipping containers coaforming to PPP-B-636. Shipments that exceed the weight limitations of this specification shall be packed in overseas-type containers conforming to PPP-B-601. The gross weigh
