4.1 This practice is useful as a screening basis for acceptance or rejection of transparencies during manufacturing so that units with identifiable flaws will not be carried to final inspection for rejection at that time.4.2 This practice may also be employed as a go-no go technique for acceptance or rejection of the finished product.4.3 This practice is simple, inexpensive, and effective. Flaws identified by this practice, as with other optical methods, are limited to those that produce temperature gradients when electrically powered. Any other type of flaw, such as minor scratches parallel to the direction of electrical flow, are not detectable.1.1 This practice covers a standard procedure for detecting flaws in the conductive coating (heater element) by the observation of polarized light patterns.1.2 This practice applies to coatings on surfaces of monolithic transparencies as well as to coatings imbedded in laminated structures.1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.4 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. For specific precautionary statements, see Section 6.1.5 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.

定价： 515元 加购物车

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1.1 This specification covers a coextruded polyethylene composite pressure pipe with a butt welded aluminum tube reinforcement between the inner and outer layers. The inner and outer polyethylene layers are bonded to the aluminum tube by a melt adhesive. Included is a system of nomenclature for the polyethylene-aluminum-polyethylene of raised temperature (PERT/AL/PE-RT) pipes, the requirements and test methods for materials, the dimensions and strengths of the component tubes and finished pipe, adhesion tests, and the burst and sustained pressure performance. Also given are the requirements and methods of marking. The pipe covered by this specification is intended for use in air conditioning and refrigeration (ACR), underground irrigation systems, radiant panel heating systems, baseboard, snow- and ice-melt systems, and gases that are compatible with composite pipe.1.2 This specification relates only to composite pipes incorporating a butt welded aluminum tube having both internal and external polyethylene layers. The welded aluminum tube is capable of sustaining internal pressures. Pipes consisting of metallic layers not butt welded together and plastic layers other than polyethylene are outside the scope of this specification.1.3 Specifications for fittings for use with pipe meeting the requirements of this specification are given in Annex A1.1.4 This specification excludes crosslinked polyethylene-aluminum-crosslinked polyethylene pipes (see Specification F1281).1.5 Units—The values stated in SI units are to be regarded as standard. The values given in parentheses after SI units are provided for information only and are not considered standard.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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.7 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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