1、Reference number ISO/TR 15855:2001(E) ISO 2001 TECHNICAL REPORT ISO/TR 15855 First edition 2001-08-01 Copper, lead and zinc sulfide concentrates Step-by-step procedure for the testing of static scales Concentrs sulfurs de cuivre, de plomb et de zinc Procdure pas pas pour les essais des bascules stat
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5、ddress given below. ISO 2001 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or I
6、SOs member body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.ch Web www.iso.ch Printed in Switzerland ii ISO 2001 All rights reservedISO/TR 15855:2001(E) ISO 2001 All rights reserved iii Forew
7、ord ISO (the International Organization 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 techni
8、cal committee has been established has 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 e
9、lectrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to
10、the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. In exceptional circumstances, when a technical committee has collected data of a different kind from that which is normally published as an International Sta
11、ndard (“state of the art”, for example), it may decide by a simple majority vote of its participating members to publish a Technical Report. A Technical Report is entirely informative in nature and does not have to be reviewed until the data it provides are considered to be no longer valid or useful
12、. Attention is drawn to the possibility that some of the elements of this Technical Report may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO/TR 15855, was prepared by Technical Committee ISO/TC 183, Copper, lead and zinc ores an
13、d concentrates.TECHNICAL REPORT ISO/TR 15855:2001(E) ISO 2001 All rights reserved 1 Copper, lead and zinc sulfide concentrates Step-by-step procedure for the testing of static scales 1 Scope This Technical Report outlines simple procedures to check the performance and calibration status of static sc
14、ales. The test sequence is intended for routine applications, generating results which can be used to calculate explicit scale performance parameters (precision, bias and linearity) in accordance with the relevant equations shown in ISO 12745, Copper, lead and zinc ores and concentrates Precision an
15、d bias of mass measurement techniques. It is stressed that the basic procedures described below do not replace comprehensive technical manuals published by National Weights and Measures authorities to comply with legal and other specific requirements. 2 General Information ISO 12745 provides a gener
16、al summary of testing principles and procedures for weighbridges (in 5.3), hopper scales (in 5.4), gantry scales (in 5.5) and platform scales (in 5.6), augmented by a list of test mass categories in clause 6. Weighbridges, hopper and platform scales represent the most common systems encountered in t
17、he context of concentrate mass determinations for commercial consignments. Although the principles of testing are similar, details vary depending on the availability and number of certified weights and the level of automation (in the case of hopper scales having built-in reference weights). 3 Freque
18、ncy of testing The frequency of in-house and routine scale performance tests (in addition to mandatory certification intervals stipulated by regulatory authorities) observed in practice ranges from none to as high as three times per consignment in the case of some fully automated weighing hopper ins
19、tallations. The disparity reflects the absence of explicit guidelines as well as different risk perceptions and available resources. Routine scale performance checks carried out once per commercial consignment, before the loading or discharge commences, are regarded as an optimum requirement by many
20、 operators. However, it is practically impossible to carry out such checks once per commercial consignment, because the tests cause delays in loading or discharge and are very expensive. In addition, improved stability of scales in recent times should allow reduced frequency of testing. It is theref
21、ore recommended that the frequency of testing be decided by agreement between the parties concerned, based on the risk and the reliability of the scales. 4 Precision test procedures 4.1 General Although precision tests do not require certified test weights, it is stressed that they provide no inform
22、ation concerning potential bias or linearity problems.ISO/TR 15855:2001(E) 2 ISO 2001 All rights reserved 4.2 Determining the precision of weighbridges by replicate tests a) Check, and if necessary, adjust the zero setting of the scale. b) Place a truck or rail wagon (selected at random) on the weig
23、hbridge and record the gross weight W 1 . c) Remove the truck or wagon from the weighbridge and check/adjust the zero setting again. d) Place the same truck or rail wagon from step b) on the weighbridge and record the gross weight W 2 . A minimum of four duplicate determinations (four data pairs W 1
24、 , W 2 ) are recommended in order to calculate the scale precision, in accordance with ISO 12745. 4.3 Determining the precision of hopper scales by replicate tests a) Check and, if necessary, adjust the zero setting of the scale. b) Use a test mass of about five to ten times the scales readability o
25、r sensitivity (e.g. 25 kg for a scale sensitivity of 5 kg) to produce paired weight measurements with and without this test mass respectively, and record the corresponding gross weights W 1 and W 2 . A minimum of six data pairs (W 1 , W 2 ) from a single weighing cycle are recommended in order to ca
26、lculate the scale precision, in accordance with ISO 12745. 5 Calibration (bias and linearity test) procedures 5.1 General Bias and linearity tests require at least one certified reference weight of suitable mass (1 t or 2 t). In the case of hopper scales, the weight or weights are usually suspended
27、from the weigh frame. The use of a large number of smaller reference weights (for example a set of 100 individually certified test weights of 20 kg each, in accordance with the requirements of National Weights and Measures authorities) is a suitable alternative, especially where the entire test sequ
28、ence has to be performed manually. 5.2 Calibration procedure using a single certified test weight This procedure applies to situations where only one certified test weight (or set of small weights having an equivalent total mass) covering a small part of the scales designated range is available. Ind
29、ividual calibration points at increasing initial loads are generated by adding the certified test weight W cert at a given load state W 0 and comparing the expected scale reading W 1 W cert W 0 to the observed value W 2 . The scale deviation at a given point is thus given by W 2 W 1 . A minimum of t
30、hree determinations is recommended, and one test each at initial loads of: zero; approximately half the scale capacity; approximately full scale capacity less the certified weight. a) Check and, if necessary, adjust the zero setting of the scale. b) Place the certified test weight on the scale and r
31、ecord the first calibration point (data pair) W 1 , W 2 . c) Remove the certified test weight, add a quantity of material of approximately equal to half the scale capacity, and record the exact weight. d) Add the certified test weight to the scale and record the second calibration point, W 1 , W 2 .
32、ISO/TR 15855:2001(E) ISO 2001 All rights reserved 3 e) Remove the certified test weight, add a further quantity of material to produce a total approximately equal to half the scale capacity, and record the exact weight. f) Add the certified test weight to the scale and record the third calibration p
33、oint W 1 , W 2 . 5.3 Calibration procedure using a set of certified test weights This procedure applies to situations where a set of certified test weights covering the scales entire designated range is available. Individual calibration points over the full range are generated by the incremental add
34、ition or subtraction of individual test weights, comparing the expected (certified) weight W 1 at each stage with the corresponding scale readout W 2 . The scale deviation at a given point is calculated as W 2 W 1 as in 5.2. a) Check and, if necessary, adjust the zero setting of the scale. b) Place
35、the first certified test weight on the scale and record the first calibration point (data pair) W 1 , W 2 . c) Add the second certified test weight to the scale and record the second calibration point W 1 , W 2 . d) Repeat step c) for the third and subsequent test weight in the series. e) Remove the individual test weights, one at a time, and record the resulting data pairs, W 1 , W 2 as well as the final readout at zero load.ISO/TR 15855:2001(E) ICS 73.060.99 Price based on 3 pages ISO 2001 All rights reserved
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