ISO 4021:1992 pdf download – Hydraulic fluid power – Particulate contamination analysis – Extraction of fluid samples from lines of an operating system
1 Scope
This International Standard specifies procedures for extracting fluid samples from a hydraulic fluid power system under operation. The preferred method is to extract fluid samples from a main flowline of an operating hydraulic sys- tem in such a manner that the particulate contami- nant in the sample is representative of the fluid flowing at the point of sampling. An alternative method is to extract a sample from the reservoir of an operating hydraulic system, but this method should only be used if a suitable sam- pler is not fitted. The samples taken are used for particulate con- tamination analysis.
2 Normative references
The following standards contain provisions which, throug,h reference in this text, constitute provisions of this International Standard. At the time of publi- cation, the editions indicated were valid. All stan- dards are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of ap- plying the most recent editions of the standards in- dicated below. Members of IEC and IS0 maintain registers of currently valid International Standards.
ISO 3722:1976, Hydraulic fluid power – Fluid sample containers – Qualiiying and controlling cleaning methods.
ISO 5598:1985, Fluid power systems and components – Vocabulary.
3 Definitions
For the purposes of this International Standard, the definitions given in ISO 5598 and the following defi- nitions apply.
3.1 clean sample bottle: Sample bottle which has been thoroughly cleaned and verified in accordance with IS0 3722.
3.2 fluid sampling, line: The extraction of a sample of fluid from a turbulent section of a ftow stream.
3.3 fluid sampling, reservoir: The extraction of a sample of fluid from the reservoir of an operating system.
3.4 sampler: A device which allows the extraction of a quantity of representative fluid from the hy- draulic system. (See figures 1 and 2.)
3.5 turbulent flow: Fluid flow in which particle movement, anywhere in the flow, varies rapidly in velocity and direction. Flow may be turbulent when the Reynolds number (ne) is greater than 2 300 and can be assumed to be turbulent when Re 2 4 000. See annex A.
4.1.2 Ensure that the extraction point is clear of the boundary layer of the system pipework and the axis of the sampler is approximately perpendicular to the main flow stream, preferably entering the system pipework from the top. Arrange the point of exit of the sampled fluid such that the flow is directed ver- tically downwards.
4.2.1 If a sampler cannot be fitted directly to the system, then samples may be extracted from the system reservoir. However, extreme care should be taken to avoid adding further contamination at the sampling point. Samples extracted by this means are less representative of the system contamination than samples extracted by means of live dynamic sampling.