Nas 1638 pdf
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see the nas vs iso cleanliness chart below for a good approximation. the first involves sending a fluid sample to a laboratory for analysis. example: nas> oooç cass 5, ( ref table l) ; or nasx) ooç gass 103, ( ref table pdf il) appli cable docum ents bjþljcatjqns. the concept pdf of the code can be seen in table 1 and it is based upon a fixed particle size distribution of the contaminant over a size range of > 5 to > 100 µm. data is sorted into cumulative particle counter. this sae aerospace standard defines cleanliness levels for particulate contamination of hydraulic fluids and includes methods of reporting data relating to the contamination levels. although there is no guidance given in the standard on how to quote the levels, most industrial users quote a single code which is the highest recorded in all sizes. , 9) is reported as the nas class. if nas 1638 is used, the number of par - ticles in a 100 ml sample larger than 6 and/ or 14 microns must be within the range specified by the iso 4406 code. a description is not available for this item. when apc’ s came in to use this provided a method of analysing a sample much faster than the arp598 method. learn about the encoding method of the level of contamination based on the number of particles per unit of volume in hydraulic systems, and how it has been replaced by the iso 4406 standard. nas- 1638 cleanliness requirements of parts used in hydraulic systems. this specification establishes the acceptance cleanliness limits of hydraulic fluid wetting internal surfaces of parts, assemblies, lines and fittings for use in hydraulic systems prior to storage. iso 4406 versus nas 1638 the recommended standard for defini- tion of oil cleanliness level is iso 4406. nas 1638 table the nas 1638 cleanliness standard was developed for aerospace components in the us and is still widely used for industrial and aerospace fluid power applications and in the uk north sea industries. the nas system specifies different counts within each particle range to score a specific class. each class defines a range of counts. the nas 1638 coding system defines the maximum numbers permitted of 100ml volume at various size intervals ( differential counts) rather than using cumulative counts as in iso 4406. nas1638 has been the most commonly used cleanliness. a contamination code has been added to describe the contamination levels of the fluid at the specified particle size ranges. both nas 1638 and iso 4406 focus on the methods for calculating particle counts or solid contamination levels within a fluid. unless otherwise indicated, the issue on date of invitation of bids shall apply. sae i nternational arp598 arp743 arp785. nas 1638 ( national aerospace standard) the nas system divides particles in 5 particle size ranges. it is an old standard, originally employed in 1964 to classify the cleanliness levels in hydraulic components and systems within the us aerospace industry. nas 1638 contamination level according to nas 1638: the contamination classes are defined by a number ( fromwhich indicates the maximum number of particles per 100 ml, counted on a differential basis in a given size bracket. ” * sae as4059 has been designed to replace nas/ 1964. the figures are differential counts, and the nas class is usually reported as a single figure representing the maximum allowed. nas 1638 the nas 1638 cleanliness standard was originally developed for aerospace components in the us but is still widely used for industrial and aerospace fluid power applications. the lab results contain detailed information on the condition of the fluid. compared to the iso standard, nas 1638 also distinguishes particles larger than 15 μm. nas 1638 classes based on weight of particles are not applicable to these classes and are not included. cleanliness level required for me- system nas 1638 pdf - iso 4406 code xx/ 16/ 13. comparison of the nas 1638 classes to as4059 classes is defined and the differences explained ( appendix b). the following documents form a part of this specification to the extent specified herein. nas 1638 is a standard for classification of particle contamination in oils and fluids. contamination level classes according to nas 1638 ( january 1964) the contamination classes are nas 1638 pdf defined by a number ( from 00 to 12) which indicates the maximum number of particles per 100 ml, counted on a differential basis, in a given size bracket. the contamination levels selected are an extension and simplification of the widely accepted nas 1638. standard test methods for rockwell hardness of metallic materials. nas 1638 classes based on weight of particles are not. nas 1638 was the forerunner of other contamination coding. nas 1638 is comprised of fluid cleanliness classes, each class defined in terms of maximum allowed particle. 25 to 50 microns per 100 ml. it is used widely in the uk north sea industries. inevitably, there is a requirement to be able to compare these cleanliness classification codes. iso 4406: 17/ nas 1638 pdf : : 18/ : : 19/ : 10- 11 internal leakage many of our valves have a leak proof seat design: this means that the maximum allowed oil leakage value is 1 cc/ min ( about 15- 20 drops/ min) measured with 46cst oil at 40° c at the maximum permitted pressure. a method of calibrating apc’ s. nas 1638 represents the counts of particles in five size groups: 5 to 15 microns per 100 milliliters ( ml) 15 to 25 microns per 100 ml. this distribution was based on particle contamination inside delivered aircraft hydraulic components in the 1960s. this document provides versatility in identifying a maximum class in multiple size ranges, total number of particles larger than a specific size or designating a class for each size. note - the comparisons relate to particle count data only. the nas 1638 cleanliness standard was developed for aerospace components in the us and is still widely used for industrial and aerospace fluid power applications. the figures are differential counts, and the nas class is usually reported as a single figure representing the maximum allowed particle counts ( i. most industrial users quote a single code which is the highest recorded in all sizes, e. worst case) for designated particle. 50 to 100 microns per 100 ml. however, only the largest ( worst) of the 5 individual classes ( e. a particle count will show up to have almost the same nas class rating within the different particle ranges. identification marking methods. revision history. find out the cleanliness classes, the conversion table and the download links for the standards nas 1638 and iso 4406. the nas 1638 reporting format was developed for use where the principle means pdf of counting particles was the optical microscope, with particles sized by the longest dimension per arp598. cleanliness requirements of parts used in hydraulic systems. the information normally included in a fluid condition report, along with typical targets or alarm limits, are shown in exhibit 1. according to nas 1638, particles are counted in five size classes and for each size range, a purity class from 00 to 12 is assigned accordingly. nas stands for national aerospace standard. see the nas 1638 chart below pdf for the various cleanliness levels: converting oil cleanliness standards - iso to nas to iso.