1、IS0 5308 92 4853903 0521372 511 I NTE RNAT I O NAL S TA N DAR D IS0 5308 First editior! 1992-1 2-01 Solid fertilizers - Method of checking the performance of mechanical devices for sampling of product moving in bulk Matires fertilisantes solides - Mthode de contrle des performances des appareils mca
2、niques dchantillonnage du produit en vrac en mouvement Reference number IS0 5308:1992(E) IS0 5308 92 4853903 0523373 Y58 IS0 5308:1992(E) Foreword IS0 (the International Organization for Standardization) is a worldwide federation of national standards bodies (IS0 member bodies). The work of preparin
3、g International Standards is normally carried out through IS0 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 organizations, governmental and non-governmental, in liai
4、son with ISO, also take part in the work. IS0 collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publicatio
5、n as an International Standard requires approval by at least 75 % of the member bodies casting a vote. International Standard IS0 5308 was prepared by Technical Committee iSO/TC 134, Fertilizers and soil conditioners, Sub-Committee SC 2, Sam- pling. O IS0 1992 All rights reserved. No part of this pu
6、blication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without per- mission in writing from the publisher. International Organization for Standardization Case Postale 56 CH-1 21 1 Genve 20 . Switzerland Printed in Switzerl
7、and II IS0 5308 92 = 451903 0523374 394 INTERNATIONAL STANDARD IS0 5308:1992(E) Solid fertilizers - Method of checking the performance of mechanical devices for sampling of product moving in bulk 1 Scope This International Standard specifies a method of checking the performance of mechanical devices
8、 for sampling fertilizers moving in bulk by comparison of particle size distribution with that obtained by a refer- ence method. It is applicable to any form of mechanical sampling device installed at some point in a bulk-handling sys- tem, providing that either the fertilizer passes along a conveyo
9、r belt, before or after the device, or it is sub- sequently packed in bags in order that a reference collection can be made. NOTE 1 Although the mechanical sampling may be used for the collection of samples for chemical analysis instead of or as well as for physical testing, any bias will be more ea
10、sily and economically found by size analysis than by chemical analysis of the nutrients. 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publi- cation, the editions indicated
11、 were valid. All standards are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most re- cent editions of the standards indicated below. Members of IEC and IS0 maintain registers of cur- rently valid Int
12、ernational Standards. IS0 2602:1980, Statistical interpretation of test re- sults - Estimation of the mean - Confidence in terval. IS0 3301 :I 975, Statistical interpretation of data - Comparison of two means in the case of paired ob- servations. IS0 331 0-1 :I 990, Test sieves - Technical require-
13、ments and testing - Part ?: Test sieves of metal wire cloth. IS0 3534: 1 977, Statistics - Vocabulary and symbols. IS0 3963:1977, fertilizers - Sampling from a con- veyor by stopping the belt. IS0 7742:1988, Solid fertilizers - Reduction of sam- ples. IS0 8397:1988, Solid fertilizers and soil condit
14、ioners - Test sieving. 3 Principle Collection of two series of increments, one using a mechanical device and one using a reference method, from a quantity of fertilizer passing through a bulk- handling system, and comparison of the means and variances of the particle size distribution of the two sam
15、ples. 4 Apparatus 4.1 quirements of IS0 7742. Rotary sample divider, complying with the re- 4.2 Sample containers 4.3 Set of sieves, complying with the requirements of IS0 3310-1, of nominal aperture sizes 4,OO mm, 3,35 mm, 2,80 mm, 2,36 mm, 2,OO mm, 1,40 mm, 1,00 mm and 0,50 mm. 1 IS0 5308 92 H 485
16、1903 0523375 220 IS0 5308:1992(E) 4.4 Sieve-shaking machine 5 General conditions The method of test specified in this International Standard should be carried out using a granular fertilizer. The use of a blended product may introduce additional sources of variation. If only blended fertilizer is av
17、ailable for this test, in- crements of at least 200 g shall be collected (see 6.1 .I 1. It may be necessary to check the variability of the product before carrying out this test method in order to decide whether to take more increments than are specified, or to be able to conduct the test over a sho
18、rter period of time. A statistician should be con- sulted on the most efficient and economical method of carrying out such a check. The test shall be carried out while at least 20 t (and preferably not more than 100 t) of fertilizer passes through the mechanical sampling device. 6 Procedure 6.1 Coll
19、ection of increments Carry out the operations described in 6.1.1 and 6.1.2 concurrently. 6.1.1 Using the mechanical sampling device under test, collect at least 50 increments of a suitable size1) and label them from Al to A50, etc. 6.1.2 Carry out one of the following reference col- lections. a) If
20、the fertilizer is conveyed by a conveyor belt feeding to, or extracting from, the mechanical sampling device, collect the same number of in- crements as collected in accordance with 6.1 .I by stopping the conveyor belt as specified in IS0 3963. If possible, synchronize the taking of the increments b
21、y the device under test with the taking of increments by the reference method, so that corresponding increments are taken from the same part of the fertilizer bed (see 7.2). For ex- ample, if the reference sample is taken after the sample taken by the mechanical sampling device, it may be possible t
22、o see the gap in the fertilizer bed on the conveyor belt. b) Collect the same number of full bags as the num- ber of increments specified in 6.1.1, from the same tonnage of fertilizer, at intervals corre- sponding as closely as possible to the time- intervals at which increments are taken in accorda
23、nce with 6.1 .I. Label the reference increments or bags R1 to R50, etc. If necescary, reduce the size of the increments, or the quantities of fertilizers taken in bags, to approximately the same size as those collected in 6.1 .I, by the method specified in IS0 7742. 6.2 Preparation of samples Combin
24、e the increments into equal groups to give at least 10 individual samples taken by the same method (6.1.1 and 6.1.2). The groups shall be formed of con- secutive increments, for example Al to Ag, A6 to Mix each of the individual samples thoroughly, then, proceeding in accordance with IS0 7742 using
25、the rotary sample divider (4.11, reduce each sample to a suitable mass (200 g to 250 g) for particle-size analy- sis. Alo, . . ., A46 to A50, etc. 6.3 Analysis of samples Carry out a particle-size analysis on each of the re- duced samples, obtained as described in 6.2, by the method described in IS0
26、 8397 using four or five sieves from the set (4.31, chosen to suit the fertilizer used in the test. Use the same sieves for the analysis of each reduced sample. Record the percentages of fertilizer retained on each sieve and the percentage passing through the sieve with the smallest aperture. 7 Expr
27、ession of results 7.1 General case where the increments taken by the two methods do not correspond exactly to each other For each series of n reduced samples, calculate the mean and the standard deviation for the percentage of fertilizer retained successively on each of the sieves and the percentage
28、 passing through the sieve with the smallest aperture size used. For each successive test sieve, calculate the value of the statistic t by means of the formula I- where FA and sA are the mean and the standard devi- ation for the reduced samples ob- tained using the device (6.1.1); 1) Information on
29、the minimum mass of an increment is given in ISODR 7553:1987, Fertilizers - Sampling - Minimum mass of increment to be taken to be representative of the total sampling unit. 2 IS0 5308 92 4853903 0523376 367 XR and sR are the mean and the standard devi- ation for the reduced samples ob- tained using
30、 the reference method (6.1.2). Refer to the statistical tables in IS0 2602 for the sig- nificance of the values of t obtained with 2(n - 1) de- grees of freedom. 7.2 Special cases where the increments taken by the two methods correspond exactly to each other For each pair of reduced samples, calcula
31、te the dif- ference between the percentages of fertilizer retained on each sieve in turn and the percentage passing through the sieve of smallest aperture size used. Cal- culate the mean d and the standard deviation Sd of these differences for each test sieve in turn and for the undersize fraction,
32、and calculate the value of the statistic t by means of the formula tz- d Refer to the statistical tables in IS0 3301 for the sig- nificance of the values of t obtained with (n- 1) de- grees of freedom. 8 Interpretation of results The interpretation of the individual results depends on the precision
33、that is both acceptable and practically feasible. It is to be expected that the most significant bias will be shown by the results for the percentages IS0 5308:1992(E) of fertilizer retained on the sieve of largest aperture size and passing through the sieve of smallest aper- ture size used for the
34、test, and the least significant bias by the results for the intermediate sieves. A mechanical sampling device shall be rejected if any of the values of t for the percentages of fertilizer re- tained on the sieve of largest aperture size and the percentages of fertilizer passing through the sieve of
35、smallest aperture size are significant at the 95 % confidence level. The device shall be accepted as being without bias if all the values of t are not significant at the 95 % con- fidence level. In other cases, e.g. where one of the values of t is significant at the 95 % confidence level, indicating
36、 the possibility of bias, the tests should be repeated on a larger number of samples. NOTE 2 As tests of this sort, requiring larger numbers of samples, are tedious and costly to carry out, it is rec- ommended that a statistician be consulted before further tests are carried out. Additional informat
37、ion on the performance of the tested device c$n be obtained by comparing the varl- ances si and sR obtained in 7.1 using the F-test as defined in IS0 3534. In the special case (7.21, si and si may be calculated in the normal way from the individual results. If a significantly larger variance is obta
38、ined for the tested mechanical device than for the reference method, this implies that the device is not reliable. 3 IS0 5308 92 = 4853903 0523377 OT3 IS0 5308:1992(E) UDC 631.8:620.115.2 Descriptors: fertilizers, sampling, sampling equipment, tests, performance tests, grain size analysis Price based on 3 pages
