BS ISO 14952-5-2004 Space systems - Surface cleanliness of fluid systems - Drying processes《航天系统 液体系统的表面清洁度 干燥过程》.pdf

1、BRITISH STANDARD AEROSPACE SERIES BS ISO 14952-5:2003 Space systems Surface cleanliness of fluid systems Part 5: Drying processes ICS 49.080; 49.140 BS ISO 14952-5:2003 This British Standard was published under the authority of the Standards Policy and Strategy Committee on 2 March 2004 BSI 2 March

2、2004 ISBN 0 580 43467 2 National foreword This British Standard reproduces verbatim ISO 14952-5:2003 and implements it as the UK national standard. The UK participation in its preparation was entrusted to Technical Committee ACE/68, Space systems and operations, which has the responsibility to: A li

3、st of organizations represented on this committee can be obtained on request to its secretary. Cross-references The British Standards which implement international publications referred to in this document may be found in the BSI Catalogue under the section entitled “International Standards Correspo

4、ndence Index”, or by using the “Search” facility of the BSI Electronic Catalogue or of British Standards Online. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard does not of

5、itself confer immunity from legal obligations. aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; monitor related international and European developments a

6、nd promulgate them in the UK. Summary of pages This document comprises a front cover, an inside front cover, the ISO title page, pages ii to iv, pages 1 to 3 and a back cover. The BSI copyright notice displayed in this document indicates when the document was last issued. Amendments issued since pub

7、lication Amd. No. Date Comments Reference number ISO 14952-5:2003(E) OSI 3002INTERNATIONAL STANDARD ISO 14952-5 First edition 2003-11-15 Space systems Surface cleanliness of fluid systems Part 5: Drying processes Systmes spatiaux Propret des surfaces en contact avec des fluides Partie 5: Procds de s

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13、devr iiiForeword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for w

14、hich a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all

15、 matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are c

16、irculated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. ISO 14952-5 was prepared by Technical Committee ISO/TC 20, Aircraft and space vehicles, Subcommittee SC 14, Space systems and operations. ISO 14

17、952 consists of the following parts, under the general title Space systems Surface cleanliness of fluid systems: Part 1: Vocabulary Part 2: Cleanliness levels Part 3: Analytical procedures for the determination of nonvolatile residues and particulate contamination Part 4: Rough-cleaning processes Pa

18、rt 5: Drying processes Part 6: Precision-cleaning processes BSISO149525:2003IS-25941 O5:(3002E) iv I SO 3002 All irhgts seredevrIntroduction This part of ISO 14952 describes a method for vacuum drying intricate parts or components that are likely to retain entrapped moisture when dried by normal pur

19、ging techniques. The purpose of this part of ISO 14952 is to provide processes that can be used to ensure the dryness of parts or components subjected to solvent- based or water-based cleaning processes. BSISO149525:2003INTENRATIONAL TSANDADR IS-25941 O5:(3002E)I SO 3002 All irhgts seredevr 1Space s

20、ystems Surface cleanliness of fluid systems Part 5: Drying processes 1 Scope This part of ISO 14952 provides guidance related to processes used to dry parts and components that have been subjected to solvent-based or water-based cleaning processes, and identifies drying processes that can be used fo

21、r equipment that has been cleaned for use in ground support equipment, launch vehicles and spacecraft. Vacuum drying can be used to remove entrapped fluids from intricate parts when normal purging methods have been found to be ineffective. 2 Normative references The following referenced documents ar

22、e indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 14951-3:1999, Space systems Fluid characteristics Part 3: Nitrogen ISO 14952-1:200

23、3, Space systems Surface cleanliness of fluid systems Part 1: Vocabulary 3 Terms and definitions For the purposes of this part of this document, the terms and definitions given in ISO 14952-1 apply. 4 Drying and testing procedure Components shall be thoroughly dried to remove residual cleaning, rins

24、ing and/or verification media. Effluent gas shall not exhibit an increase in moisture content greater than 5 l/l or a measurable increase in concentration of residual organic solvents. Items that do not lend themselves to this type of drying or testing procedure (i.e. special surface treatments or c

25、oatings) shall be dried in accordance with procedures agreed upon between the cleaning contractor and the customer. 5 Vacuum drying procedure 5.1 Apparatus and reagents The following items are required to accomplish the vacuum drying processes specified by this part of ISO 14952. 5.1.1 Vacuum oven,

26、with temperature control range from 45 C to 125 C. BSISO149525:2003IS-25941 O5:(3002E) 2 I SO 3002 All irhgts seredevr5.1.2 Purge (test) gas, nitrogen in accordance with ISO 14951-3, Type A. 5.1.3 Thermocouple, for independent temperature monitoring of parts. 5.2 Heating of parts Component parts sha

27、ll be placed in the vacuum oven with the thermocouple attached to the largest part placed in the oven. The oven shall be closed and purged with inert test gas, then the oven shall be heated to the desired vacuum drying temperature. The temperature of the parts shall be governed by the following crit

28、eria: a) minimum drying temperature for all parts shall be 45 C; b) maximum drying temperature for parts containing nonmetallics shall be 65 C; c) maximum temperature for drying metallic parts shall be 125 C. 5.3 Thermal vacuum drying time Once the thermocouple monitor indicates that the parts have

29、reached the desired temperature, a vacuum should be drawn on the parts and maintained for the period specified in Table 1. Once the parts have been dehydrated, the heat should be discontinued and the oven slowly back-filled with the test gas. Table 1 Vacuum drying time Values in hours Temperature Va

30、cuum oven pressure kPa 45 C 5 C 6 C 7 C 8 C 20,0 0,9 0,75 15,0 1,3 0,8 0,75 13,0 4,8 1,2 0,75 0,75 9,5 2,0 0,8 0,75 0,75 6,5 3,4 1,1 0,75 0,75 0,75 3,0 0,9 0,75 0,75 0,75 0,75 2,0 0,75 0,75 0,75 0,75 0,75 6 Gaseous purge-drying procedure 6.1 Materials Gases used in purge-drying processes shall confo

31、rm to the following requirements. a) Nitrogen, filtered to remove particulates greater than 5 m, shall be in accordance with Type A of ISO 14951-3:1999. b) Air shall contain no particulate matter greater than 5 m. The hydrocarbon content shall not exceed 10 l/l except that a total value of 20 l/l is

32、 acceptable when the portion of the total hydrocarbon content representing compounds containing 5 or more carbon atoms does not exceed 5 l/l. The relative humidity shall not exceed 60 %. BSISO149525:2003IS-25941 O5:(3002E) I SO 3002 All irhgts seredevr 36.2 Drying sample 6.2.1 Reliability sample The

33、 quantitative analysis reliability sample shall consist of a minimum of 5 % of the items dried but not less than one sample from each group of items dried. The sample shall be selected in a manner that will provide maximum representation of the lot containing production items that have been cleaned,

34、 verified and dried. A lot does not necessarily mean identical parts but does include all hardware processed in one operation. The reliability sample and the segment of production that it represents shall be clearly identified, as specified by the customer. 6.2.2 Procedure reliability Alternatively,

35、 the reliability of the drying procedure may be established for each hardware configuration and drying process. After qualification of the procedure and equipment for a specific hardware configuration, reliability sampling shall be left to the discretion of the customer. Samples for qualification of

36、 the drying process shall be selected as follows. a) Select a minimum of five cleaned, verified and dried items from each of the hardware configuration to be qualified. b) Evaluate samples in accordance with 6.3. c) Upon qualification of the drying procedure for each hardware configuration, the esta

37、blished drying cycle requirements shall be implemented. Periodic spot tests shall be made to ensure that drying procedures continue to be effective. 6.3 Drying test Unless otherwise approved by the customer, the reliability of the drying procedure for items subjected to liquids during cleaning or dr

38、ying procedures shall be determined as follows. a) Prefiltered drying gas shall be flowed through or over the affected surfaces of the item being tested. b) For hardware processed with aqueous media, the dewpoint of the drying gas entering and leaving the affected item shall be monitored to determin

39、e the presence of moisture on cleaned and dried surfaces. An increase in the moisture content of the drying gas of 5 l/l or greater shall necessitate additional drying prior to packaging or the application of protective coverings. c) For hardware processed with halogenated solvents, the effluent dry

40、ing gas shall be monitored with a halogen detector to determine if affected surfaces are free from residual solvent. If no measurable concentrations are indicated by the halogen detector, the affected surfaces shall be considered free from residual halogenated solvents. Any measurable concentration

41、above ambient in the drying gas shall necessitate additional drying prior to packaging or application of protective coverings. For hardware processed with alcohols or other hydrocarbons, the effluent drying gas shall be monitored with a hydrocarbon detector. Any measurable concentration above ambien

42、t in the drying gas shall necessitate additional drying prior to packaging or application of protective coverings. BSISO149525:2003BS ISO 14952-5:2003 BSI 389 Chiswick High Road London W4 4AL BSI British Standards Institution BSI is the independent national body responsible for preparing British Sta

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