1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS EN 4171:2011Aerospace series Paints andvarnishes Test method fordetermination of phosphoricacid indexBS EN 4171:2011 BRITISH STANDARDNational forewordThis British Standard is
2、the UK implementation of EN 4171:2011.The UK participation in its preparation was entrusted to TechnicalCommittee ACE/65/-/3, Paints, Surface Finish and ProtectiveTreatments for Aerospace Purposes for Aerospace Purposes.A list of organizations represented on this committee can beobtained on request
3、to its secretary.This publication does not purport to include all the necessaryprovisions of a contract. Users are responsible for its correctapplication. The British Standards Institution 2012ISBN 978 0 580 75592 7ICS 49.040Compliance with a British Standard cannot confer immunity fromlegal obligat
4、ions.This British Standard was published under the authority of theStandards Policy and Strategy Committee on 31 January 2012.Amendments issued since publicationDate Text affectedBS EN 4171:2011EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 4171 December 2011 ICS 49.040 English Version Aerospa
5、ce series - Paints and varnishes - Test method for determination of phosphoric acid index Srie arospatiale - Peintures et vernis - Mthode dessai pour la dtermination de lindice dacide phosphorique Luft- und Raumfahrt - Beschichtungsstoffe - Prfverfahren zur Bestimmung des Phosphorsure-Index This Eur
6、opean Standard was approved by CEN on 27 August 2011. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references c
7、oncerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN member. This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member
8、 into its own language and notified to the CEN-CENELEC Management Centre has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, I
9、reland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: Avenue Marni
10、x 17, B-1000 Brussels 2011 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 4171:2011: EBS EN 4171:2011EN 4171:2011 (E) 2 Contents Page Foreword 3 1 Scope 4 2 Normative references 4 3 Terms and definitions .4 4 Principle 4 5 Apparat
11、us .4 6 Specimen 5 7 Procedure .5 8 Results 6 9 Designation 6 10 Test report 6 BS EN 4171:2011EN 4171:2011 (E) 3 Foreword This document (EN 4171:2011) has been prepared by the Aerospace and Defence Industries Association of Europe - Standardization (ASD-STAN). After enquiries and votes carried out i
12、n accordance with the rules of this Association, this Standard has received the approval of the National Associations and the Official Services of the member countries of ASD, prior to its presentation to CEN. This European Standard shall be given the status of a national standard, either by publica
13、tion of an identical text or by endorsement, at the latest by June 2012, and conflicting national standards shall be withdrawn at the latest by June 2012. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN and/or CENELEC shall no
14、t be held responsible for identifying any or all such patent rights. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark,
15、 Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. BS EN 4171:2011EN 4171:2011 (E) 4 1 Scope This European test stan
16、dard specifies a method for the titration and determination of the phosphoric acid content of an hydroalcoholic solution for aerospace applications. This test method is relevant for the determination of total acidity and phosphoric acid content in a reactive thinner of a wash primer or in metal clea
17、ners. 2 Normative references The following referenced documents are 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. EN ISO 1513, Paints
18、and varnishes - Examination and preparation of test samples (ISO 1513) EN ISO 3696, Water for analytical laboratory use - Specification and test methods (ISO 3696) EN ISO 15528, Paints, varnishes and raw materials for paints and varnishes - Sampling (ISO 15528) 3 Terms and definitions For the purpos
19、es of this document, the following terms and definitions apply. 3.1 reactive thinner alcoholic phosphoric acid solution, which reacts with the metallic substrate and the base 3.2 metal cleaner aqueous phosphoric acid solution for the removal of slightly oxidic films on aluminium 4 Principle The phos
20、phoric acid content is determined by titration with aqueous solution of sodium or potassium hydroxide after ionisation of the phosphoric acid. Successive pH jumps allow the determination of: total acidity; phosphoric acid content. 5 Apparatus conical flasks: 250 ml; burette: 50 ml or 100 ml; PTFE co
21、ated magnetic stirrer; pipette: 10 ml; buffered solutions (pH = 4,5 and pH = 6,2); indicator solution (helianthine and phenolphtalein); automatic acid/base titrator or glass electrode (and SCE electrode); BS EN 4171:2011EN 4171:2011 (E) 5 1 N sodium or potassium hydroxide solution: (calibrate N usin
22、g phthalic acid). All chemicals are analytical reagent grade. Titration has to be carried out accordingly. 6 Specimen Test specimen shall be taken directly from the original container. See EN ISO 1513 and EN ISO 15528. 7 Procedure In the conical flask containing an accurate volume of 10 ml, (Vs), of
23、 the test specimen, add approximately 150 ml of fresh distilled water in accordance with EN ISO 3696; Introduce the magnetic stirring bar and put the erlenmeyer on the magnetic stirrer; Add few drops of both coloured indicators in case of manual procedure; Introduce the glass electrode and the SCE i
24、n case of pH-f (V) procedure; Using automatic or manual procedure add slowly the alkaline solution and record alkaline solution volume versus pH or colour change; Determine accurately the volume of alkali added to achieve the first and second end points indicated by observed jumps in pH using the po
25、tentiometric method or colour change in the case of the manual procedure. According to the pKa of the phosphoric acid (2,1, 7,2, 12,7) three main pH jumps are theoretically detected, but the two first jumps (pH 4,5 and 9) are detected with good accuracy (see Figure 1); Note V1and V2, the alkaline so
26、lution volume required to obtain these two pH jumps or colour change. Figure 1 Titration of phosphoric acid by a strong base. Typical curve CAUTION In case of solution containing phosphoric acid as only acidic material, theoretically V1 = V2 but due to carbonic acid dissolved in water V2 may be slig
27、htly higher than V1. BS EN 4171:2011EN 4171:2011 (E) 6 8 Results Acid normality: sVV )N(N11= H3PO4content: ()sVVVN3Na12= In order to avoid the contribution of the presence of any other strong acid in the test specimen, for the calculation of the phosphoric acid content only the difference (V2 V1) sh
28、all be used. 9 Designation EXAMPLE Description block PHOSPHORIC ACID INDEX Identity block EN4171 Number of this standard 10 Test report This test standard specifies a method for the titration and determination of the phosphoric acid content of an hydroalcoholic solution used in etch primer activator
29、s for aerospace applications. a) Reference to this European Standard (EN 4171); b) date; c) product designation; d) batch number; e) code number; f) N (Normality of sodium or potassium hydroxide solution); g) N1 (Acid normality); h) Na (H3PO4content); i) test procedure: coloured indicators, pH = f (
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