1、BRITISH STANDARDBS ISO 21018-1:2008Hydraulic fluid power Monitoring the level of particulate contamination of the fluid Part 1: General principlesICS 23.100.60g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g
2、55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58BS ISO 21018-1:2008This British Standard was published under the authority of the Standards Policy and Strategy Committee on 29 August 2008 BSI 2008ISBN 978 0 580 53993 0National forewordThis British Standard is the UK implementation of ISO
3、21018-1:2008.The UK participation in its preparation was entrusted by Technical Committee MCE/18, Fluid power systems and components, to Panel MCE/18/-/6, Contamination control.A list of organizations represented on this committee can be obtained on request to its secretary.This publication does not
4、 purport to include all the necessary provisions of a contract. Users are responsible for its correct application.Compliance with a British Standard cannot confer immunity from legal obligations.Amendments/corrigenda issued since publicationDate CommentsReference numberISO 21018-1:2008(E)INTERNATION
5、AL STANDARD ISO21018-1First edition2008-04-15Hydraulic fluid power Monitoring the level of particulate contamination of the fluid Part 1: General principles Transmissions hydrauliques Surveillance du niveau de pollution particulaire des fluides Partie 1: Principes gnraux BS ISO 21018-1:2008ii iiiCon
6、tents Page Foreword iv Introduction v 1 Scope . 1 2 Normative references . 1 3 Terms and definitions. 2 4 Health and safety 3 4.1 General. 3 4.2 Electric power . 3 4.3 Mechanical fluid power 4 4.4 Process liquids . 4 5 Selection of monitoring technique 4 5.1 General. 4 5.2 Selection 5 6 Procedures a
7、nd precautions . 5 6.1 General. 5 6.2 Obtaining representative samples 5 6.3 Off-line sampling. 5 6.4 On-line analysis 6 6.5 In-line analysis 6 6.6 Suction (sip) analysis from reservoirs or containers . 6 6.7 Calibration procedures. 7 6.8 Checking data validity 7 6.9 Training 7 6.10 Controlling the
8、precision of the technique 8 7 Test report . 8 Annex A (informative) Summary of various technique attributes. 9 Annex B (informative) Description and relative merits of different contaminant monitoring techniques . 15 Bibliography . 24 BS ISO 21018-1:2008iv Foreword ISO (the International Organizati
9、on for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established ha
10、s the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. Inte
11、rnational Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publica
12、tion as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rig
13、hts. ISO 21018-1 was prepared by Technical Committee ISO/TC 131, Fluid power systems, Subcommittee SC 6, Contamination control. ISO 21018 consists of the following parts, under the general title Hydraulic fluid power Monitoring the level of particulate contamination of the fluid: Part 1: General pri
14、nciples Part 3: Use of the filter blockage technique A Part 2, dealing with the calibration and verification procedure for field contamination monitoring, and a Part 4, dealing with the use of the light extinction technique, are under development. BS ISO 21018-1:2008vIntroduction In hydraulic fluid
15、power systems, power is transmitted through a liquid under pressure within a closed circuit. The liquid is both a lubricant and power-transmitting medium. The presence of solid particulate contamination in the liquid interferes with the ability of the hydraulic liquid to lubricate and causes wear to
16、 the components. The extent of this form of contamination in the liquid has a direct bearing on the performance and reliability of the system and it is necessary that this be controlled to levels that are considered appropriate for the system concerned. Hydraulic filters are used to control the amou
17、nt of particulate contamination to a level that is suitable for both the contaminant sensitivity of the system and the level of reliability required by the user. Operators of hydraulic equipment are gradually defining maximum particle concentration levels for components, systems and processes, beyon
18、d which corrective actions are implemented to normalize the levels. These are often referred to as the required cleanliness level (RCL). The cleanliness level is obtained by sampling the hydraulic liquid and measuring the particulate contamination level. If the level is above the RCL, then correctiv
19、e actions are necessary to restore the situation. To avoid taking unnecessary actions, which can often prove costly, precision in sampling and measuring the particulate contamination level is required. A comprehensive range of measurement equipment is available, but the instruments used are usually
20、laboratory-based. This often requires that the equipment is operated in a special environment by specialist laboratories and this delays delivery of the test result to the user. To overcome this disadvantage, instruments are being continuously developed to determine the particulate contamination lev
21、el, either using equipment that can be operated in or near the workplace or directly using on-line or in-line techniques. For equipment operated in the workplace, direct traceability to national measurement standards might not be appropriate, or relevant, and the instruments are used to monitor the
22、general level of particulate contamination or to inform the user of a significant change in the level. When a significant change in the particulate contamination level is detected, the actual level is then usually qualified by using an approved particle-counting method. Also, these monitors can have
23、 simplified circuitry compared to similar laboratory units and this means that they are not so precise. In addition, some instruments are designed to work on the “go/no-go” principle and their ability to rapidly evaluate the cleanliness level has resulted in an increase in their usage both in the fl
24、uid power industry and other markets. Unfortunately, the lack of a standardized method for their use, recalibration (if applicable) and means of checking the output validity means that the variability in the measurement data is at a level higher than is desirable. This International Standard has bee
25、n developed to provide uniform and consistent procedures for instruments that are used for monitoring the contamination levels in hydraulic systems, especially those where direct traceability to national measurement standards is not possible or is not applicable. BS ISO 21018-1:2008blank1Hydraulic f
26、luid power Monitoring the level of particulate contamination of the fluid Part 1: General principles 1 Scope This part of ISO 21018 specifies methods and techniques that are applicable to the monitoring of particulate contamination levels in hydraulic systems. It also describes the relative merits o
27、f various techniques so that the correct monitor for a given application can be selected. The techniques described in this part of ISO 21018 are suitable for monitoring a) the general cleanliness level in hydraulic systems, b) the progress in flushing operations, c) support equipment and test rigs.
28、This part of ISO 21018 can also be applicable for other liquids (e.g. lubricants, fuels and process liquids). NOTE Instruments used to monitor particulate contamination are not considered as or claimed to be particle counters, even if they use the same physical principles as particle counters. 2 Nor
29、mative references The following referenced documents are indispensable for the application 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 3722, Hydraulic fluid power
30、 Fluid sample containers Qualifying and controlling cleaning methods ISO 4021, Hydraulic fluid power Particulate contamination analysis Extraction of fluid samples from lines of an operating system ISO 4406:1999, Hydraulic fluid power Fluids Method for coding the level of contamination by solid part
31、icles ISO 5598, Fluid power systems and components Vocabulary ISO 11171, Hydraulic fluid power Calibration of automatic particle counters for liquids ISO 11500:1997, Hydraulic fluid power Determination of particulate contamination by automatic counting using the light extinction principle ISO 11943,
32、 Hydraulic fluid power On-line automatic particle-counting systems for liquids Methods of calibration and validation ISO 12103-1:1997, Road vehicles Test dust for filter evaluation Part 1: Arizona test dust BS ISO 21018-1:20082 3 Terms and definitions For the purposes of this document, the terms and
33、 definitions given in ISO 5598 and the following apply. 3.1 automatic particle counter APC instrument that automatically counts and sizes individual particles suspended in a liquid using the light extinction principle 3.2 coincidence detection of two or more particles as a single particle NOTE Adapt
34、ed from ISO 11500:1997, definition 3.2. 3.3 dynamic range ratio of the largest and smallest particle size that a sensor can analyse 3.4 filter medium fabric of the filter that removes and retains particles 3.5 gel shapeless material that lacks definition and can interfere with the counting or monito
35、ring process NOTE Gels are usually formed by chemical reaction with the hydraulic liquid. 3.6 in-line analysis analysis of a fluid sample of the liquid by an instrument that is permanently connected to a working flow line and where all of the liquid in that line passes through the sensor 3.7 off-lin
36、e analysis analysis of a fluid sample by an instrument that is not directly connected to the hydraulic system 3.8 on-line analysis analysis performed on a fluid supplied directly to the instrument by a continuous line from the hydraulic system NOTE The instrument can be either permanently connected
37、to the flow line or connected prior to analysis. 3.9 mesh type of filter medium that is made by weaving strands of wire or material filaments 3.10 particle size characteristic dimension of a particle that defines the magnitude of the particle in terms of a physically measurable dimension related to
38、the analysis technique used, such as the longest dimension or the equivalent spherical diameter and shall be stated in each standard 3.11 pore size size of hole in the filter medium as stated by the instrument manufacturer BS ISO 21018-1:200833.12 qualitative data data that have less precision or ac
39、curacy than quantitative methods and usually gives results in ranges rather than exact numbers 3.13 quantitative data data in the form of an exact numerical value of a parameter 3.14 required cleanliness level RCL liquid cleanliness level specified for a system or process 3.15 sampler device for ext
40、racting a representative sample from a larger source 3.16 silt very small particles ( 20/18/15 (see ISO 4406:1999). d) Typical analysis time is 5 min. B.2.3 Limitations The following key limitations have been identified. a) It requires a high concentration of particles for accurate detection 19/17/1
41、4 (see ISO 4406:1999). b) The particle size distribution is based upon particle volume. c) It is not generally used in the fluid power industry. d) The test set-up can be bulky. e) It cannot be used with multi-phase liquids. B.3 Electrical sensing zone B.3.1 Outline An electrically conducting liquid
42、 is drawn through a small, electrically insulated orifice having electrodes positioned in the liquid on either side of the orifice. When no particles are present, the impedance between the electrodes remains constant. When a particle having a conductivity different from that of the liquid passes thr
43、ough the orifice, it generates an electrical pulse proportional to the volume of the particle. This type of unit is not frequently used for monitoring oil-based systems as the analysis process involves a number of other stages, either separating the particles and re-suspending them in an electrolyte
44、 or preparing a series of chemicals to make the oil conducting. The technique can be used in systems with water-based liquids. Also see ISO 13319. BS ISO 21018-1:200817B.3.2 Key features The following key features have been identified. a) It can accommodate a wide particle size range (0,5 m to 1 500
45、 m) by using different analytical orifices. b) It provides precise, volumetric measurements. c) It gives the particle-size distribution. d) It typically has an analysis time of 5 min if the sample is analysed directly. B.3.3 Limitations The following key limitations have been identified. a) It can b
46、e used only for off-line analysis. b) It requires the test liquid to be electrically conducting. c) It is necessary that the electrical conductivity of the particulate contamination present in the test sample be different from that of the carrier liquid. d) The sample time is extended (typically by
47、20 min to 40 min) when the sample liquid is non-conducting. e) It is not widely used in the fluid power industry. B.4 Filter blockage method B.4.1 Outline The principle of the filter-blockage method is the determination of the change in the characteristics of a filter mesh or screen having a known n
48、umber of uniform openings (or pores) as the contaminated liquid passes through it. Particles greater in size than the pore are removed and the filter gradually blocks up. This causes either the differential pressure across the filter to increase (constant-flow principle) or a reduction in the flow r
49、ate through the filter (constant-differential-pressure principle). The concentration of particles in the test liquid sample with a size greater than the filter pore size can then be estimated either by considering the number of blocked pores (degree of blockage) and the volume of liquid that passed through the filter or by calibration. The test result is converted into a cleanliness code (see ISO 4406). As the pressure drop across the filter is proportional to the viscosity, it is necessary to correct the data from constant flow units for c
