ISO 4406 pdf download.Hydraulic fluid power — Fluids — Method for coding the level of contamination by solid particles
1 Scope
This International Standard 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 normative documents contain provisions which, through reference in this text, constitute provisions of this International Standard. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. However, parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC maintain registers of currently valid International Standards. ISO 4407:1 991 , Hydraulic fluid power — Fluid contamination — Determination of particulate contamination by the counting method using a microscope. ISO 1 1 1 71 :1 999, Hydraulic fluid power — Calibration of automatic particle counters for liquids. ISO 1 1 500:1 997, Hydraulic fluid power — Determination of particulate contamination by automatic counting using the light extinction principle.
3 Code definition
3.1 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 is generally a doubling of the contamination level. The original code in accordance with ISO 4406:1 987 stated the reporting at two sizes, W 5 µm and W 1 5 µm, but the sizes in this revision have been changed to account for the use of a different calibration standard for optical automatic particle counters. The reported sizes are W 4 µm(c), W 6 µm(c) and W 1 4 µm(c), the last two of these being equivalent to the 5 µm and 1 5 µm particle sizes obtained using the ISO 4402:1 991 method of calibrating automatic particle counters. ISO 4402:1 991 has been replaced by ISO 1 1 1 71 :1 999. Throughout this International Standard, the use of µm(c) means that particle size measurements are carried out using an automatic particle counter which has been calibrated in accordance with ISO 1 1 1 71 . Measurement of particles using an optical microscope as specified in ISO 4407:1 991 establishes the size of a particle as being equal to its longest dimension, whereas an automatic particle counter 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, W 5 µm and W 1 5 µm, are unchanged from those specified in ISO 4406:1 987.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 that the sample obtained is representative of the fluid circulation in the system.3.3 Allocation of scale numbers 3.3.1 The scale numbers are allocated according to the number of particles counted per millilitre of the fluid sample (see Table 1 ). 3.3.2 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 meaningful. 3.4 Determination of code using automatic particle counter analysis 3.4.1 Counting shall be undertaken in accordance with ISO 1 1 500 or another recognised method, using an automatic particle counter calibrated to ISO 1 1 1 71 . 3.4.2 A scale number shall be allocated to the number of particles equal to or larger than 4 µm(c). 3.4.3 A second scale number shall be allocated to the number of particles equal to or larger than 6 µm(c). 3.4.4 A third scale number shall be allocated to the number of particles equal to or larger than 1 4 µm(c). 3.4.5 The three numbers shall be written one after the other and separated by oblique strokes (slashes). EXAMPLE A code of 22/1 8/1 3 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 µm(c) and more than 40 and up to and including 80 particles equal to or larger than 1 4 µm(c) in 1 ml of a given fluid sample.