Hydraulic fluid power

BS ISO 4406:2021 pdf free.Hydraulic fluid power一Fluids 一Method for coding the level of contamination by solid particles.
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, Hydraulic fluid 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.orgJ
4 Code definitions
4.1 General
The purpose ot this code is to simplity the reporting ot particle count aata by converting me numoers or 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 tm and  15 tm. 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 pAm(c),  6 im(c) and  14 i ni(c), .is per ISO 11171. The List two oft hese .are equivalent to the S im irid 15 i m particle sizes specilied in the first edition.
NOTE Throughout this document, the USC of pm(c) means that particle size measLirements are carried out using an APC that has been calibrated in accordante with ISO 11171 or a partide contamination monitor (PCM) alihr.itrd to ISO 2101H-3 or ISO 2101H-4.
Measurement of particles using an optical nhiroscope as specified within ISO 4407 estbIishes (he size of .i particle .is being equal to its longest dimension, whereas .in APC derives the size of an equivalent particle from its cross-sectional area, a value different in most cases from that determined using a fll icroscope.
The particle sizes to he reported for measurement by microscope 5 ni and >15 tni are unchanged from those specified in the first edition of this document
CAUTION — Particle counts are aflccted by a variety of factors. These lactors 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 that the sample obtained is representative of the fluid circulation within the system.
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 ofIhe particles as follows:
— the first scale number represents the number of p.irtwles equal to or larger than 4 unir millilare of lluid
— the second scale number represents the number of particles equal to or larger than fr m(c) er inilliltire of fluid and
the third scale number represents the number of particles equal to or larger than 14 tm(cj per millilitre of fluid.
The code for microscope counting comprises two scale numbers using 5 ni and 15 urn.
4.3 Allocation otscale numbers
4.3.1 The scale numbers are allocated according to the number of particles counted per millilitre of 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 ol particles per millilitre in Table 1, has been adopted to keep the number of scale numbers within a reasoiiable limit and to ensure that each step is meaningful.
4.4.1 Counting shall be undertaken in accordance with ISO 11500 or another recognized method,using an APC calibrated to ISO 11171 or a PCM calibrated to IS0 21018-3 or ISO 21018-4.
4.4.2 A first scale number shall be allocated to the number of particles equal to or larger than 4 um(C).
4.4.3 A second scale number shall be allocated to the number of particles equal to or larger than 6 um().
4.4.4 A third scale number shall be allocated to the number of particles equal to or larger than 14 um(c).
4.4.5 The three numbers shall be written one after the other and separated by oblique strokes (slashes).
EXAMPLE A code of 22/18/13 signifies that there are more than 20 000 and up to and including 40 000 particles equal to or larger than 4 μm(C). more than 1 300 and up to and including 2 500 particles equal to or larger than 6 um(c), and more than 40 and up to and including 80 particles equal to or larger than 14 um(C) in 1 ml. of a given fluid sample.
Graphical presentation of ISO code results shall be as described in Annex A.
4.4.6 When applicable, include either(too numerous to count) or “一”(no requirement to count) notations when reporting the scale number.
EXAMPLE 119/14 means that this sample has too many particles equal to or larger than 4 um(C) to count.EXAMPLE2 – /19/ 14 means that there was no requirement to count particles equal to or larger than 4 um(c).
4.4.7 When the raw data in one of the size ranges results in a particle count of fewer than 20 particles,the scale number for that size range shall be labelled with the symbol“2”
EXAMPLE A code of 14/12/27 signifies that there are more than 80 and up to and including 160 particles equal to or larger than 4 μm(c) per millilitre and more than 20 and up to and including 40 particles equal to or larger than 6 um(c) per millilitre. The third part of the code, 27, indicates that there are more than 0,64 and up to and including 1,3 particles equal to or larger than 14 μm(c) per millilitre but less than 20 particles were counted,which lowers statistical confidence. Due to this lower confidence, the 14 um(C) part of the code can be higher than 7, indicating a particle count of more than 1,3 particles per millilitre.
4.5 Determination of code using microscope sizing
4.5.1Counting shall be undertaken in accordance with ISO 4407.
4.5.2 A scale number shall be allocated to the number of particles equal to or larger than 5 um.
4.5.3 A second scale number shall be allocated to the number of particles equal to or larger than 15 um.BS ISO 4406 pdf free download.Hydraulic fluid power