1、 Reference number ISO 29042-4:2009(E) ISO 2009INTERNATIONAL STANDARD ISO 29042-4 First edition 2009-02-15 Safety of machinery Evaluation of the emission of airborne hazardous substances Part 4: Tracer method for the measurement of the capture efficiency of an exhaust system Scurit des machines valua
2、tion de lmission de substances dangereuses vhicules par lair Partie 4: Mthode par traceur pour le mesurage de lefficacit de captage dun systme dchappement ISO 29042-4:2009(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobes licensing policy, this file may be pri
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7、1 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2009 All rights reservedISO 29042-4:2009(E) ISO 2009 All rights reserved iii Contents Page Foreword iv Introduction v 1 Scope 1 2 Normative references 1 3 Terms and definitions .1 4 Principle2 5 Simpli
8、fied expression of the capture efficiency.2 6 Test method3 6.1 General procedure.3 6.2 Measurement of concentration, C 3 5 6.3 Application to a specific group of machines 6 7 Control parameters and influencing factors.6 7.1 General6 7.2 Control parameters6 7.3 Influencing factors on capture efficien
9、cy .8 8 Test report 8 Annex A (informative) Simplified calculation of random component of uncertainty on C 3(95 %).9 Bibliography 10 ISO 29042-4:2009(E) iv ISO 2009 All rights reservedForeword ISO (the International Organization for Standardization) is a worldwide federation of national standards bo
10、dies (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 has the right to be represented on that committee. International organizatio
11、ns, 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. International Standards are drafted in accordance with the rules given in the
12、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. Publication as an International Standard requires approval by at least 75 % of th
13、e 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 rights. ISO 29042-4 was prepared by Technical Committee ISO/TC 199, Safety of
14、 machinery. ISO 29042 consists of the following parts, under the general title Safety of machinery Evaluation of the emission of airborne hazardous substances: Part 1: Selection of test methods Part 2: Tracer gas method for the measurement of the emission rate of a given pollutant Part 3: Test bench
15、 method for the measurement of the emission rate of a given pollutant Part 4: Tracer method for the measurement of the capture efficiency of an exhaust system The following parts are under preparation: Part 5: Test bench method for the measurement of the separation efficiency by mass of air cleaning
16、 systems with unducted outlet Part 6: Test bench method for the measurement of the separation efficiency by mass of air cleaning systems with ducted outlet Part 7: Test bench method for the measurement of the pollutant concentration parameter A room method for the measurement of the pollutant concen
17、tration parameter and a decontamination index are to form the subjects of future parts 8 and 9. ISO 29042-4:2009(E) ISO 2009 All rights reserved v Introduction The structure of safety standards in the field of machinery is as follows: a) type-A standards (basic safety standards) giving basic concept
18、s, principles for design, and general aspects that can be applied to all machinery; b) type-B standards (generic safety standards) dealing with one safety aspect or one type of safeguard that can be used across a wide range of machinery: type-B1 standards on particular safety aspects (e.g. safety di
19、stances, surface temperature, noise); type-B2 standards on safeguards (e.g. two-hand controls, interlocking devices, pressure-sensitive devices, guards); c) type-C standards (machine safety standards) dealing with detailed safety requirements for a particular machine or group of machines. This part
20、of ISO 29042 is a type-B standard as stated in ISO 12100-1. The requirements of this document can be supplemented or modified by a type-C standard. For machines which are covered by the scope of a type-C standard and which have been designed and built according to the requirements of that standard,
21、the requirements of that type-C standard take precedence. ISO/TC 199 has a mandate in this area to produce type-A and type-B standards, which will allow verification of conformity with the essential safety requirements. ISO 29042-4 is based on EN 1093-4:1996, amended by Amendment 1:2008, published b
22、y the European Committee for Standardization (CEN). INTERNATIONAL STANDARD ISO 29042-4:2009(E) ISO 2009 All rights reserved 1 Safety of machinery Evaluation of the emission of airborne hazardous substances Part 4: Tracer method for the measurement of the capture efficiency of an exhaust system 1 Sco
23、pe This part of ISO 29042 specifies a method based on a tracer technique for measuring the capture efficiency of an exhaust system installed on a machine. It is applicable to all types of test environment test bench, room or field (see ISO 29042-1) but is only applicable if the tracer shows aerodyna
24、mic behaviour comparable to that of the real pollutant. The measurement of the capture efficiency of an exhaust system can serve for d) evaluation of the performance of a machines exhaust system, e) evaluation of the improvement of an exhaust system, f) comparison of exhaust systems for machines of
25、similar design, g) ranking of exhaust systems according to their capture efficiency, h) determination of the air flow rate of an exhaust system to achieve a given level of capture efficiency, and i) determination of the state-of-the-art of machine exhaust systems with respect to capture efficiency.
26、2 Normative 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 12100-1:2003, Safety o
27、f machinery Basic concepts, general principles for design Part 1: Basic terminology, methodology 3 Terms and definitions For the purposes of this document, the terms and definitions given in ISO 12100-1 and the following apply. 3.1 capture efficiency cratio of the mass flow rate of a given pollutant
28、 directly collected by an exhaust system to the uncontrolled mass flow rate of this pollutant emitted from the machine ISO 29042-4:2009(E) 2 ISO 2009 All rights reserved3.2 tracer technique use of gaseous substances with an aerodynamic behaviour comparable with the hazardous substance under consider
29、ation and for which concentrations can be reliably measured 4 Principle The principle of the measurement method consists of: a) emitting a tracer simulating the aerodynamic behaviour of the real pollutant, with the tracer flow rate, q E ; b) measuring the flow rate, q C , of the tracer collected by
30、the exhaust system. 5 Simplified expression of the capture efficiency The capture efficiency, c , expressed as a percentage, is given by Equation (1): C c E 100 q q = (1) The tracer flow rate, q E , is determined by emitting the tracer at constant flow rate directly into the exhaust duct and by meas
31、uring the average tracer concentration in a cross-section of the duct, then using Equation (2): E21 () qQ CC = (2) where Q is the average air flow rate in the duct during the measurement period of q E ; C 1is the average ambient concentration of the tracer before the measurements (background level);
32、 C 2is the average concentration of the tracer in the duct (emission of tracer in the duct). The tracer flow rate, q C , is determined by emitting the tracer at a constant flow rate, q E , at a characteristic point or zone of the emission of the real pollutant (e.g. at the locations in the emission
33、zone furthest from the exhaust system) and by measuring the average concentration of tracer in the same points of the duct, then using Equation (3): C31 () qQ CC = (3) where Q is the average air flow rate in the duct during the measurement period of q C ; 1 C is the average ambient concentration of
34、the tracer after the background level is stabilized; C 3is the average concentration of the tracer in the duct (emission at a selected location). The capture efficiency is expressed as a percentage using Equation (4): C3 1 c E2 1 () 100 100 () qQ C C qQ C C = (4) ISO 29042-4:2009(E) ISO 2009 All rig
35、hts reserved 3 If the exhaust flow rate can be considered as being constant, then Q = Q , and the expression can be simplified as Equation (5): 31 c 21 100 CC CC = (5) The capture efficiency is then determined by measuring only concentrations in the exhaust duct. 6 Test method 6.1 General procedure
36、The measurement procedure is shown in Figure 1, while Figure 2 shows a typical test recording. In order to be able to measure the concentration by sampling the air in the duct, it is assumed that the tracer is well mixed with the air. 1)NOTE Devices can be added to the duct to reduce the mixing leng
37、th. At least three tests shall be performed. 1) In EN 1093-4:1996, on which this part of ISO 29042 is based, a recommendation was given for the use of the procedures for straight ducts described in ISO 4053-1:1977. ISO 4053-1 has since been withdrawn and is no longer publicly available; at the time
38、of publication of this part of ISO 29042, it had not been replaced by another International Standard. ISO 29042-4:2009(E) 4 ISO 2009 All rights reservedTest phases one and four: measurement without tracer emission Test phase two: measurement with tracer emission in the duct Test phase three: measure
39、ment with tracer emission simulating the real pollutant Key 1 sampling 2 pump 3 analyser 4 injection 5 tracer gas flow meter 6 tracer gas cylinder (pure or diluted tracer gas) 7 ambient concentration, C 1or 1 C 8 concentration, C 29 concentration, C 3Figure 1 Measurement procedure for simple exhaust
40、 system using tracer gas ISO 29042-4:2009(E) ISO 2009 All rights reserved 5Key X time, s Y tracer concentration Figure 2 Typical test recording 6.2 Measurement of concentration, C 3Considering an emitter whose flow rate changes suddenly from 0 to q E , concentration C 3rises progressively as a funct
41、ion of time. The curve of variation of C 3roughly shows two time constants: the first, relatively small, corresponds to the accumulation of tracer in the volume directly under the influence of the exhaust system; the second, which is larger, corresponds to the accumulation of tracer in the rest of t
42、he room a part of the tracer, escaping from the zone of direct influence of the exhaust system, is secondarily and indirectly collected over a longer period of time. Since the efficiency of a system is based on the direct collection of the pollutant, the efficiency is defined on the basis of the det
43、ermination of the value of C 3corresponding to the first time constant. In practice, and except for very small rooms, the time constant of the room is much larger than the time constant of the collection system, so that the measurement may be facilitated by averaging the value of the efficiency over
44、 a time interval of a few minutes after obtaining the first quasi-equilibrium state. In small rooms, an increase in the ambient concentration can impair the quality of the measurement. For this reason, the measurement should only be accepted if the ratio 11 21 CC CC is lower than 0,05. Concentration
45、 C 1should be measured 1 min after dosing of the tracer is stopped. Because of the fluctuations in the response, as can be observed in Figure 2, concentration C 3should be established as an average over a reasonable period of time. For a given measurement, the effective averaging period can be calcu
46、lated as the time constant for the measuring system multiplied by the number of samples taken. To allow ISO 29042-4:2009(E) 6 ISO 2009 All rights reservedstatistical analyses of the signal, leading to results such as minimum capture efficiency or relative standard deviation, the time constant of the
47、 measuring system should be adjusted to a defined value. This adjustment can be achieved by use of a buffer volume on the sampling line or by use of a digital filter. The time constant should be adjusted to 10 s. The interval between successive samples should be greater than or equal to the time con
48、stant for the measuring system in use. Statistical analysis of the signal C 3can determine the concentration of C 3(95 %). This is the value of C 3which is exceeded for 95 % of the specified measurement time. This value leads to the minimum capture efficiency, the calculation of which is given by Eq
49、uation (6): 31 c 21 (95%) (95 %) CC CC = (6) Assuming the distribution of C 3is Gaussian, C 3(95 %) can be derived from the mean value and the standard deviation of C 3using Equation (7): 333 (95 %) 1 ,64 ( ) CCC = (7) The measurement result shall always be stated together with the uncertainty of the result. The uncertainty may be calculated according to Annex A. A typical percentage is 95 %, but other values above 75 % may b
