17704692435
4.1 This classification was developed to permit the addition of descriptive symbols and values for further new formulations with improved properties without complete reorganization of the standard and to facilitate the incorporation of future new test methods to keep pace with changing industry requirements.1.1 This classification provides guidance to engineers and users in the selection of practical vinyl chloride plastics for medical applications and further provides a method for specifying these materials by use of a simple line call-out designation. This classification excludes vinyl chloride plastics used in long-term implants.1.2 Use is made of a classification scheme based on the premise that the composition of vinyl chloride plastics, copolymers, fillers, plasticizers, stabilizers, and other additives in these systems can be arranged into characteristic material designations.1.3 In all cases where the provisions of this classification system would conflict with those of the detailed specification for a particular device, the latter shall take precedence.NOTE 1: For cases in which the vinyl chloride plastic may be used for purposes where the requirements are too specific to be completely described by this classification system, it is advisable for the purchaser to consult the supplier to secure adjustment of the properties to suit the actual conditions to which the device is to be subjected.1.4 The biocompatibility of vinyl chloride plastics as a class of materials has not been established. Since many compositions and formulations fall under this class, it is essential that the fabricators/device manufacturers assure the safety and efficacy of the specific composition or formulation, in its intended application, using state-of-the-art test methods.1.5 This classification is to assist the interface between the material supplier and the device manufacturer (fabricator) who purchases a formulated vinyl chloride plastic for a component. For those device manufacturers (fabricators) who do their own formulating, compounding, extrusion, molding, and so forth, this classification does not apply.1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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3.1 In this test method, susceptibility to localized corrosion of aluminum is indicated by a protection potential (Eprot) determined by cyclic galvanostaircase polarization (1). The more noble this potential, the less susceptible is the alloy to initiation of localized corrosion. The results of this test method are not intended to correlate in a quantitative manner with the rate of propagation of localized corrosion that one might observe in service.3.2 The breakdown (Eb), and protection potentials (Eprot) determined by the cyclic GSCP method correlate with the constant potential corrosion test (immersion-glassware) result for aluminum (1, 6, 7). When the applied potential was more negative than the GSCP Eprot, no pit initiation was observed. When the applied potential was more positive than the GSCP Eprot, pitting occurred even when the applied potential was less negative than Eb.3.2.1 Severe crevice corrosion occurred when the separation of Eb and Eprot was 500 mV or greater and Eprot was less than −400 mV Vs. SCE (in 100 ppm NaCl) (1, 6, 8). For aluminum, Eprot determined by cyclic GSCP agrees with the repassivation potential determined by the scratch potentiostatic method (1, 9). Both the scratch potentiostatic method and the constant potential technique for determination of Eprot require much longer test times and are more involved techniques than the GSCP method.3.3 DeBerry and Viebeck (3-5) found that the breakdown potentials (Eb) (galvanodynamic polarization, similar to GSCP but no kinetic information) had a good correlation with the inhibition of localized corrosion of 304L stainless steel by surface active compounds. They attained accuracy and precision by avoiding the strong induction effect which they observed by the potentiodynamic technique.3.4 If this test method is followed using the specific alloy discussed it will provide (GSCP) measurements that will reproduce data developed at other times in other laboratories.3.5 Eb and Eprotobtained are based on the results from eight different laboratories that followed the standard procedure using aluminum alloy 3003-H14 (UNS A93003). Eb and Eprot are included with statistical analysis to indicate the acceptable range.1.1 This test method covers a procedure for conducting cyclic galvanostaircase polarization (GSCP) to determine relative susceptibility to localized corrosion (pitting and crevice corrosion) for aluminum alloy 3003-H14 (UNS A93003) (1).2 It may serve as guide for examination of other alloys (2-5). This test method also describes a procedure that can be used as a check for one's experimental technique and instrumentation.1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
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