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适用范围：<p>Although a cleaning action is imparted to the test component, it is not the intent of this practice to serve as a cleaning procedure. Components are normally cleaner after each consecutive test; thus repeated tests may be used to establish process limits for a given component (Fig. 4). A specific set of test parameters must be supplied by the agency specifying cleanliness limits. Fig. 1, Fig. 2, and Fig. 3 may be used as a guide to establish the desired parameters of test fluid, vibration, extraction, and analysis.</p> <p>The curve in Fig. 4 shows the typical behavior of a component when tested for cleanliness several consecutive times. Stabilization generally occurs before the fifth successive run. The stabilized region starts where a horizontal line through the maximum stabilized value intersects the curve.</p> <p>The allowable cleanliness limit of a test component should be based on the cleanliness requirements of the system in which it will be used and the assigned value should be greater than the maximum stabilized value. When defining the allowable cleanliness limits, an important consideration is that the accuracy of the results decreases as the allowable limit value approaches the stabilized value.</p><p class="fig" id="f00002"><img src="http://www.astm.org/HTTP/IMAGES/15091.gif"><br> <span class="bold">FIG. 4 Contamination per Test Run Versus Consecutive Test Run Number</span></p><p id="s00002">1.1 These practices cover sampling procedures for use in determining the particle cleanliness of liquids and liquid samples from components. Three practices, A, B, and C, have been developed on the basis of component geometry in order to encompass the wide variety of configurations. These practices establish guidelines to be used in preparing detailed procedures for sampling specific components. <p class="desc" id="N00001"> <span class="smallcap">Note</span> 18212;The term cleanliness used in these practices refers to solid particles in the liquid. It does not generally cover other foreign matter such as gases, liquids, and products of chemical degradation. Cleanliness with respect to particulate contamination does not necessarily give any indication of the other types of contamination.</p> </p> <p id="s00003">1.2 All components, regardless of application, may be tested provided (<span class="italic">1</span>) the fluid medium selected is completely compatible with the materials, packing and fluid used in the test component, and test apparatus, and (<span class="italic">2</span>) the fluid is handled in accordance with the manufacturer''s recommendations and precautions. A liquid shall be used as the test fluid medium. These test fluids may be flushing, rinsing, packing, end use operating, or suitable substitutes for end use operating fluids. (<span class="bold">Warning</span><span class=''unicode''>x2014;</span>Practices for sampling surface cleanliness by the vacuum cleaner technique (used on clean room garments and large storage tanks) sampling gaseous fluids and handling hazardous fluids such as oxidizers, acids, propellants, and so forth, are not within the scope of the practices presented; however, they may be included in addendums or separate practices at a later date. </p><p>Substitute fluids are recommended in place of end item fluids for preassembly cleanliness determinations on components using hazardous end item fluids. After obtaining the sample, the substitute fluid must be totally removed from the test part with particular caution given to the possibility of trapped fluid. It is hazardous to use a substitute fluid for testing assembled parts where the fluid can be trapped in dead ends, behind seals, and so forth.)</p> <p class="desc" id="N00002"> <span class="smallcap">Note</span> 28212;The word fluid used in these practices shall be assumed to be a liquid unless otherwise stated.</p> <p id="s00004">1.3 The cleanliness of assemblies with or without moving parts may be determined at the time ......