{"id":6155,"date":"2026-09-20T20:13:18","date_gmt":"2026-09-20T17:13:18","guid":{"rendered":"https:\/\/aesinn.com\/test-ve-olcum-hizmetleri\/iso-4406-iso-11171-iso-16232-hidrolik-ve-akiskan-sistemlerde-partikul-temizlik-sinifi-ve-olcumu\/"},"modified":"2026-09-21T22:08:39","modified_gmt":"2026-09-21T19:08:39","slug":"iso-4406-iso-11171-iso-16232-hidrolik-ve-akiskan-sistemlerde-partikul-temizlik-sinifi-ve-olcumu","status":"publish","type":"page","link":"https:\/\/aesinn.com\/en\/test-ve-olcum-hizmetleri\/iso-4406-iso-11171-iso-16232-hidrolik-ve-akiskan-sistemlerde-partikul-temizlik-sinifi-ve-olcumu\/","title":{"rendered":"ISO 4406 \/ ISO 11171 \/ ISO 16232 \u2014 Particle Cleanliness Class and Measurement in Hydraulic and Fluid Systems"},"content":{"rendered":"<h2 class=\"wp-block-heading\">Why Fluid Cleaning is Critical: Particulate Contamination as a Root Cause<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">A significant portion of failures in hydraulic and lubrication systems are root-caused by solid particle contamination of the fluid. The working clearances between servo valves, proportional valves, high-pressure pumps, and bearings are often on the micron scale; abrasive particles entering these clearances lead to wear, seizure, internal leakage, and loss of efficiency.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Wear caused by contamination often forms a self-reinforcing cycle: the wear particles formed trigger further wear. Therefore, monitoring fluid cleanliness as a measurable quantity forms the basis of predictive maintenance and system reliability. This content provides an informative framework on how cleanliness is classified and measured.<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n\n<li>Particle contamination is a common root cause of wear, internal leakage, adhesion, and sudden failures.<\/li>\n\n\n<li>Servo valves and high-precision components are sensitive to particles on the micron scale.<\/li>\n\n\n<li>Wear particles trigger new wear, creating a self-reinforcing cycle of degradation.<\/li>\n\n\n<li>Measurable cleanliness class is an objective indicator of predictive maintenance.<\/li>\n\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Structure and Logic of the ISO 4406 Cleaning Code<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">ISO 4406 expresses the solid particle contamination of a fluid with a three-digit code; for example, 18\/16\/13. These three numbers respectively represent the range of particles larger than certain size thresholds per milliliter: the first number corresponds to particles larger than 4 microns (\u00b5m(c)), the second to particles larger than 6 microns, and the third to particles larger than 14 microns. Each threshold represents a cumulative count encompassing that size and larger.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The basic logic of the code is based on a logarithmic scale: as the code number increases by one unit, the number of particles per milliliter in that size range approximately doubles. Thus, a very wide range of contamination can be expressed with three short and comparable numbers. A larger code number means a higher particle count, i.e., a more contaminated fluid. This page aims to explain this logic of the code rather than giving exact particle counts; assigning a code to a specific system requires accredited laboratory measurement and assessment by a qualified engineer.<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n\n<li>The code consists of three numbers and represents the thresholds of 4 \/ 6 \/ 14 microns, respectively.<\/li>\n\n\n<li>Each number corresponds to the cumulative number range per milliliter of particles larger than the relevant size.<\/li>\n\n\n<li>The scale is logarithmic: each code increase means the particle count range approximately doubles.<\/li>\n\n\n<li>The larger the code, the dirtier the fluid.<\/li>\n\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Counting Methods: ISO 4407 Microscopic Counting and Automatic Particle Counter (APC)<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Generating the ISO 4406 code requires the counting and sizing of particles, and two main approaches are used for this. ISO 4407 describes a reference method in which the fluid is vacuum-filtered through a membrane filter, the particles are collected on the filter, and counted and sized using an optical microscope\u2014manually or with image analysis software. The microscope method is considered a strong reference for hard particle contamination due to its resistance to interferences such as additives and water\/air bubbles.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Automatic particle counters (APCs) generally operate on the principle of light extinction; size and number are quickly determined by measuring how much light particles obstruct as a fluid passes through a sensor. The APC method provides fast and repeatable results for field and routine monitoring; however, proper sample preparation is important as water droplets, air bubbles, and certain additives can lead to false counts. The two methods complement each other: APC provides speed and continuity, while microscopy provides verification and resistance to interference.<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n\n<li>ISO 4407: Counting on membrane filters using an optical microscope (manual or image analysis)<\/li>\n\n\n<li>APC: Fast, automatic counting and sizing based on the principle of light attenuation.<\/li>\n\n\n<li>The microscopic method is considered a more resistant reference to interference.<\/li>\n\n\n<li>APC is fast for field monitoring; sample preparation against water, air and additive interference is critical.<\/li>\n\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">ISO 11171: NIST Traceable Calibration of Automated Particle Counters<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">To ensure that results from automated particle counters are comparable across different devices and laboratories, a common calibration basis is required. ISO 11171 is the standard defining the calibration of automated particle counters for liquids; it specifies performance requirements such as flow rate, sensor volume accuracy, resolution, and coincidence error, and ensures that all devices are calibrated against the same traceable reference.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">This calibration is based on traceable reference materials from the US National Institute of Standards and Technology (NIST). In this context, the \u00b5m(c) notation is used for particle sizes, indicating the NIST-certified size; where &#039;(c)&#039; means certified size, distinguishing it from values obtained using older methods. Traceability of the calibration is a prerequisite for the reliability and reproducibility of the ISO 4406 code.<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n\n<li>ISO 11171 defines the requirements for APC calibration for liquids.<\/li>\n\n\n<li>It includes parameters such as flow rate, resolution, and collision error.<\/li>\n\n\n<li>Calibration is based on NIST traceable reference materials.<\/li>\n\n\n<li>\u00b5m(c) designation indicates certified, traceable particle size.<\/li>\n\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">ISO 16232: Component (Technical) Cleaning and Manufacturing Residue<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">While ISO 4406 classifies the intrinsic cleanliness of a fluid, ISO 16232 addresses the amount of solid contaminants remaining on the surface of a component, i.e., technical cleanliness. In automotive and general manufacturing, particulate residue left on a part (valve body, injector, pump component, hydraulic block, etc.) after washing and assembly can be a source of contamination throughout the life of the assembled system.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">In the ISO 16232 approach, particles are separated from the component by extraction (washing, shaking, ultrasonic, etc.) with a suitable liquid, then collected on a membrane filter and analyzed. The analysis can be performed using complementary techniques such as gravimetric methods that measure total mass, optical methods that count particles according to size classes, and compositional analysis (e.g., SEM-EDS) to determine the source of the particles. This method is applied in accordance with VDA 19 documents, which are widely used in the automotive sector, and is particularly important in contamination-sensitive systems such as brakes and injection systems.<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n\n<li>ISO 16232 measures residual contamination (technical cleanliness) on the component surface, not the fluid itself.<\/li>\n\n\n<li>Particles are separated by extraction (washing\/ultrasonic) and collected in a membrane filter.<\/li>\n\n\n<li>Analysis can be performed using gravimetric, particle counting, and compositional analysis (SEM-EDS).<\/li>\n\n\n<li>In the automotive industry, it is implemented in accordance with VDA 19; it is critical for systems such as brakes and fuel injection.<\/li>\n\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Determining the Target Cleanliness Class and Sampling<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">The target cleanliness class is determined by the cleanliness required by the most sensitive component in the system. Components with narrow clearances, such as servo and proportional valves and high-pressure piston pumps, require significantly cleaner fluid compared to simpler circuits with gear pumps. The ISO 4406 target codes recommended by component manufacturers are evaluated in conjunction with factors such as operating pressure and criticality. Determining the target code on a system-by-system basis is a decision requiring a qualified engineer&#039;s technical assessment.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The reliability of measurement results depends on accurate sampling. It is essential that the sample is taken from the flowing line, from a representative point, and in clean sample containers; interference such as air bubbles, water, and external contaminants must be avoided. Improper sampling can lead to misleading codes that do not reflect the true situation; therefore, the sampling procedure is an integral part of the measurement chain.<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n\n<li>The target class is selected according to the most sensitive component in the system (e.g., servo valve, high-pressure pump).<\/li>\n\n\n<li>Component manufacturer recommendations are evaluated together with pressure and criticality.<\/li>\n\n\n<li>The sample should be taken from the flowing line, from a representative point, and in clean containers.<\/li>\n\n\n<li>Air, water, and external pollution initiatives lead to misleading results.<\/li>\n\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Application Areas and Related Sectors<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Particle cleanliness class measurement and component cleanliness are applied in numerous sectors where fluid reliability is crucial. Mobile and industrial hydraulics, manufacturing machinery, power generation and wind turbine gearboxes, and heavy industrial facilities such as steel and paper mills are typical users of these measurements.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Component cleaning (ISO 16232) is particularly prominent in the automotive and automotive parts industries, where contaminant-sensitive parts such as injection, brake, drivetrain, and electric vehicle components are manufactured. Aerospace, defense, and precision hydraulic component manufacturing are also areas with high cleanliness requirements. This page aims to provide general information for Turkish manufacturers and OEMs in these sectors.<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n\n<li>Mobile and industrial hydraulic systems<\/li>\n\n\n<li>Energy generation and wind turbine gearboxes.<\/li>\n\n\n<li>Automotive and automotive parts industry (injection, brakes, transmission, EV components)<\/li>\n\n\n<li>Aerospace, defense, and precision hydraulic component manufacturing.<\/li>\n\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Information Note and AES Accreditation Scope<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">AES is a Type A inspection body accredited by T\u00dcRKAK, and its accreditation scope is limited to the 6.1 Electrical Installation area. The ISO 4406, ISO 4407, ISO 11171, and ISO 16232 topics discussed on this page relate to the area of fluid and component cleaning, which falls outside the scope of electrical installation accreditation.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">AES is NOT an accredited inspection\/certification body in this context. This content is for informational purposes only and is within the framework of authorized engineer technical evaluation. Determining the target cleanliness class for a specific system, interpreting measurement results, and making conformity decisions should be carried out through accredited laboratory measurements and authorized engineer evaluation.<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n\n<li>AES&#039;s T\u00dcRKAK accreditation scope is limited to only section 6.1 Electrical Installation.<\/li>\n\n\n<li>Fluid\/component cleanliness issues are outside the scope of this accreditation.<\/li>\n\n\n<li>This content is for informational purposes only; final evaluation rests with a qualified engineer.<\/li>\n\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Related Services<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n\n<li><a href=\"https:\/\/aesinn.com\/en\/muayene-periyodik-kontrol\/mekanik-ekipman-muayeneleri\/titresim-analizi-ve-kestirimci-bakim-pompa-fan-kompresor-motor\/\">Vibration Analysis and Predictive Maintenance<\/a><\/li>\n\n\n<li><a href=\"https:\/\/aesinn.com\/en\/muayene-periyodik-kontrol\/mekanik-ekipman-muayeneleri\/guvenilirlik-merkezli-bakim-rcm-ve-guvenilirlik-verisi-iso-14224-ve-sae-ja1011\/\">Reliability-Centric Maintenance (RCM) and Reliability Data<\/a><\/li>\n\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Frequently Asked Questions<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">What do the three numbers in the ISO 4406 code mean?<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">The three numbers represent the cumulative number range per milliliter of particles larger than 4, 6, and 14 microns, respectively. For example, in the code 18\/16\/13, each number represents a logarithmic range corresponding to the respective size threshold, and the higher the code, the dirtier the fluid. This information conveys the logic of the code, not the exact number of particles.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">What does it mean for the code number to increase by one unit?<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">ISO 4406 uses a logarithmic scale. As the code number increases by one unit, the range of particles per milliliter in that size range approximately doubles. Thus, a very wide range of pollution can be expressed with three short and comparable numbers.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">What is the difference between ISO 4407 and an automated particle counter (APC)?<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">ISO 4407 is a reference method that counts particles on a membrane filter using an optical microscope, and the additive is more resistant to water and air interference. APC, on the other hand, generally performs fast and automated counting based on the principle of light attenuation; it is practical for field monitoring but sample preparation is important. The two methods complement each other.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Why is ISO 11171 important and what does \u00b5m(c) stand for?<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">ISO 11171 defines the calibration of automated particle counters according to NIST traceable references, thus enabling comparison of results from different instruments and laboratories. The letter &#039;(c)&#039; in \u00b5m(c) indicates the NIST traceable certified particle size.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">How does ISO 16232 differ from ISO 4406?<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">ISO 4406 classifies the in-depth cleanliness of a fluid, while ISO 16232 measures the residual contamination remaining on the surface of a component after washing and assembly, i.e., its technical cleanliness. Particles are separated by extraction, collected in a filter, and evaluated by gravimetric, counting, or compositional analysis.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Does AES conduct inspections or certifications in these areas?<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">No. AES&#039;s T\u00dcRKAK accreditation scope is limited only to 6.1 Electrical Installations. AES is not an accredited inspection\/certification body in this scope. This content is for informational purposes only and is within the framework of authorized engineer technical evaluation.<\/p>","protected":false},"excerpt":{"rendered":"<p>In hydraulic and fluid systems, the root cause of most failures is particulate contamination. This information sheet explains the rationale behind the ISO 4406 cleaning code, ISO 4407 and automated particulate counting (APC) methods, ISO 11171 calibration, and ISO 16232 component cleaning for manufacturers and OEMs.<\/p>","protected":false},"author":1,"featured_media":6158,"parent":2518,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"_acf_changed":false,"_kad_blocks_custom_css":"","_kad_blocks_head_custom_js":"","_kad_blocks_body_custom_js":"","_kad_blocks_footer_custom_js":"","_kadence_starter_templates_imported_post":false,"_kad_post_transparent":"","_kad_post_title":"","_kad_post_layout":"","_kad_post_sidebar_id":"","_kad_post_content_style":"","_kad_post_vertical_padding":"","_kad_post_feature":"","_kad_post_feature_position":"","_kad_post_header":false,"_kad_post_footer":false,"_kad_post_classname":"","slim_seo":{"title":"ISO 4406 \/ 11171 \/ 16232 Particle Cleanliness Class","description":"ISO 4406 cleaning code, ISO 4407 microscopic counting, ISO 11171 APC calibration, and ISO 16232 engineering-focused information on component cleaning."},"_pplb_hide_from_list":false,"footnotes":""},"class_list":["post-6155","page","type-page","status-publish","has-post-thumbnail","hentry"],"acf":[],"taxonomy_info":[],"featured_image_src_large":["https:\/\/aesinn.com\/wp-content\/uploads\/iso4406-aes-kart-1024x1024.png",1024,1024,true],"author_info":{"display_name":"Emre Metin","author_link":"https:\/\/aesinn.com\/en\/author\/yonetim\/"},"comment_info":"","_hostinger_reach_plugin_has_subscription_block":false,"_hostinger_reach_plugin_is_elementor":false,"_links":{"self":[{"href":"https:\/\/aesinn.com\/en\/wp-json\/wp\/v2\/pages\/6155","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/aesinn.com\/en\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/aesinn.com\/en\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/aesinn.com\/en\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/aesinn.com\/en\/wp-json\/wp\/v2\/comments?post=6155"}],"version-history":[{"count":2,"href":"https:\/\/aesinn.com\/en\/wp-json\/wp\/v2\/pages\/6155\/revisions"}],"predecessor-version":[{"id":6164,"href":"https:\/\/aesinn.com\/en\/wp-json\/wp\/v2\/pages\/6155\/revisions\/6164"}],"up":[{"embeddable":true,"href":"https:\/\/aesinn.com\/en\/wp-json\/wp\/v2\/pages\/2518"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/aesinn.com\/en\/wp-json\/wp\/v2\/media\/6158"}],"wp:attachment":[{"href":"https:\/\/aesinn.com\/en\/wp-json\/wp\/v2\/media?parent=6155"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}