BS ISO 4406:2021 pdf download – Hydraulic fluid power — Fluids — Method for coding the level of contamination by solid particles

BS ISO 4406:2021 pdf download – Hydraulic fluid power — Fluids — Method for coding the level of contamination by solid particles 3 Terms and definitions No terms and definitions are listed in this document. ISO and IEC maintain terminological databases for use in standardization at the following addresses: — ISO Online browsing platform: available at https:// www .iso .org/ obp — IEC Electropedia: available at http:// www .electropedia .org/ 4 Code definitions 4.1 General The purpose of this code is to simplify the reporting of particle count data by converting the numbers of particles into broad classes or codes, where an increase in one code generally represents a doubling of the contamination level. The original code, in accordance with the first edition of this document, stated the reporting at two sizes: ≥ 5 µm and ≥ 15 µm. The sizes in this document account for the use of a different calibration standard for optical automatic particle counters (APCs). The reported sizes are ≥ 4 µm(c), ≥ 6 µm(c) and  14 µm(c), as per ISO 11171. The last two of these are equivalent to the 5 µm and 15 µm particle sizes specified in the first edition. NOTE Throughout this document, the use of µm(c) means that particle size measurements are carried out using an APC that has been calibrated in accordance with ISO 11171 or a particle contamination monitor (PCM) calibrated to ISO 21018-3 or ISO 21018-4. Measurement of particles using an optical microscope as specified within ISO 4407 establishes the size of a particle as being equal to its longest dimension, whereas an APC derives the size of an equivalent particle from its cross-sectional area, a value different in most cases from that determined using a microscope. The particle sizes to be reported for measurement by microscope ❓ 5 µm and ❓ 15 µm are unchanged from those specified in the first edition of this document. 4.2 Basis of code The code for contamination levels using APCs or PCMs comprises three scale numbers that permit the differentiation of the dimension and the distribution of the particles as follows: the first scale number represents the number of particles equal to or larger than 4 millilitre offluid; the second scale number represents the number of particles equal to or larger than 6~millilitre of fluid: and the third scale number represents the number of particles equal to or larger than 1...