BS ISO 4406 pdf free download

BS ISO 4406:2021 pdf free download.Hydraulic fluid power – Fluids – Method for coding the level of contamination by solid particles.
This document specifies the code to be used in defining the quantity of solid particles in the fluid used in a given hydraulic fluid power system.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 4407, Hydraulic fluid power — Fluid contamination — Determination of particulate contamination by the counting method using an optical microscope
ISO 11171, Hydraulic fluid power — Calibration of automatic particle counters for liquids
ISO 11500, Hydraulicfluid power— Determination of the particulate contamination level of a liquid sample by automatic particle counting using the light-extinction principle
ISO 21018-3, Hydraulic fluid power — Monitoring the level of particulate contamination of the fluid — Part 3: Use of the filter blockage technique
ISO 21018-4, Hydraulic fluid power — Monitoring the level of particulate contamination in the fluid — Part 4: Use of the light extinction technique
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 pm and  15 pm. 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 pm(c,  6 pm(c) and
 14 pru(c), as per ISO 11171. The l.ist two oft hese are equivalent to t he S pm a ml 1S pm part ide sizes specified in the first edition.
NOTE Throughout this document, the use of pm(c) means that particle size measurements are carried out using an AP( that has been calibrated in accordance with ISO 11171 or a particle contamination monitor (I’CM) talibrated to 1St) 2101H-3 or ISO 21018-4.
Measurenient of particles using an optical microscope as specified within ISO 4407 establishes the size of a particle .is being equal to its longest dimension, whereas an AI’C derives the size of an equivalent particle from its cross-sectional area, a value different in most cases troni that determined using a ft icroscope.
The particle sizes to he reported (or measurement by microscope z 5 pm and  15 pm are unchanged from those specified in the first edition of this document,
CAUTION — Particle counts are affected by a variety of factors. These factors include procurement of sample, particle counting accuracy and the sample container (where used), and its cleanliness. Proper care should be taken during sample procurement to ensure thait the sample obtained is representative of the fluid circulation within the system.
4.2 Basis of code
The code for contanlination levels using APCs or PCMs comprises three scale numbers that permit the differentiation ofthe dimension and the distribution of the particles as follows:
— the first scale number represents the number of particles equal to or larger than 4 .mjj per millilitre of lluid,
— the second scale number represents the number of p.irticles equal to or larger than 6.pm(c) per millilitre of fluid: and
— the third scale number represents the number of particles equal to or larger than 14 ini(cj per milhilitre of fluid.
The code for microscope counting comprises two scale numbers using 5 pm and 15 pm.
4.3 Allocation of scale numbers
4.3.1 The scale numbers are allocated according to the number of particles counted per millili(re 0 the fluid sample (see Table 1).
4.3.2 A step ratio of generally two, as given between the upper and lower limits for the number of particles per millilitre in Table 1. has been adopted to keep the number of scale numbers within a reasonable limit and to ensure that each step is nieaningful.BS ISO 4406 pdf download.