1、BSI Standards PublicationBS ISO 18301:2014Animal and vegetable fatsand oils Determinationof conventional mass pervolume (litre weight in air) Oscillating U-tube methodBS ISO 18301:2014 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of ISO 18301:2014.The UK participat
2、ion in its preparation was entrusted to TechnicalCommittee AW/307, Oilseeds, animal and vegetable fats and oils andtheir by-products.A list of organizations represented on this committee can beobtained on request to its secretary.This publication does not purport to include all the necessaryprovisio
3、ns of a contract. Users are responsible for its correctapplication. The British Standards Institution 2014. Published by BSI StandardsLimited 2014ISBN 978 0 580 80493 9ICS 67.200.10Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published und
4、er the authority of theStandards Policy and Strategy Committee on 30 September 2014.Amendments issued since publicationDate Text affectedBS ISO 18301:2014 ISO 2014Animal and vegetable fats and oils Determination of conventional mass per volume (litre weight in air) Oscillating U-tube methodCorps gra
5、s dorigines animale et vgtale Dtermination de la masse volumique conventionnelle (poids du litre dans lair) Mthode du tube en U oscillantINTERNATIONAL STANDARDISO18301First edition2014-09-01Reference numberISO 18301:2014(E)BS ISO 18301:2014ISO 18301:2014(E)ii ISO 2014 All rights reservedCOPYRIGHT PR
6、OTECTED DOCUMENT ISO 2014All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission. Pe
7、rmission can be requested from either ISO at the address below or ISOs member body in the country of the requester.ISO copyright officeCase postale 56 CH-1211 Geneva 20Tel. + 41 22 749 01 11Fax + 41 22 749 09 47E-mail copyrightiso.orgWeb www.iso.orgPublished in SwitzerlandBS ISO 18301:2014ISO 18301:
8、2014(E) ISO 2014 All rights reserved iiiContents PageForeword ivIntroduction v1 Scope . 12 Normative references 13 Terms and definitions . 14 Principle 15 Apparatus . 26 Reagents 27 Sampling 28 Preparation of the test sample and test portion . 29 Procedure. 39.1 Apparatus preparation . 39.2 Apparatu
9、s calibration . 49.3 Measurement 410 Calculation 411 Precision . 511.1 Interlaboratory test. 511.2 Repeatability limit, r 511.3 Reproducibility limit, R .512 Test report . 5Annex A (informative) Interlaboratory test 6Bibliography 8BS ISO 18301:2014ISO 18301:2014(E)ForewordISO (the International Orga
10、nization 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 establis
11、hed 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 electrotechnical standardization
12、.The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the different types of ISO documents should be noted. This document was drafted in accordance with th
13、e editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).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. Details of any paten
14、t rights identified during the development of the document will be in the Introduction and/or on the ISO list of patent declarations received (see www.iso.org/patents).Any trade name used in this document is information given for the convenience of users and does not constitute an endorsement.For an
15、 explanation on the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISOs adherence to the WTO principles in the Technical Barriers to Trade (TBT) see the following URL: Foreword - Supplementary informationThe committee responsible for this
16、 document is ISO/TC 34, Food products, Subcommittee SC 11, Animal and vegetable fats and oils.iv ISO 2014 All rights reservedBS ISO 18301:2014ISO 18301:2014(E)IntroductionThe conventional mass per volume (“litre weight in air”, sometimes called “apparent density” or “conventional density”) is an imp
17、ortant parameter for the shipping of oils and fats. It is used to convert the dipped volume of oil in a tank into the mass of oil in the tank and is thus usually measured at loading and discharge of a ship. The manual method (see ISO 6883) uses a pyknometer; a method which requires a skilled technic
18、ian to perform it correctly. The automatic method is simpler to carry out and temperature control might also be easier. ISO 2014 All rights reserved vBS ISO 18301:2014BS ISO 18301:2014Animal and vegetable fats and oils Determination of conventional mass per volume (litre weight in air) Oscillating U
19、-tube method1 ScopeThis International Standard specifies a method for the determination of the conventional mass per volume of vegetable and animal oils and fats within the range of 0,800 kg/l to 1,000 kg/l which are in a single-phase liquid state at the test temperature.This method is not intended
20、for use in calibrating online density meters.2 Normative referencesThe following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of
21、the referenced document (including any amendments) applies.ISO 661, Animal and vegetable fats and oils Preparation of test sample3 Terms and definitionsFor the purposes of this document, the following terms and definitions apply.3.1conventional mass per volumelitre weight in airmass of the substance
22、, divided by its volume, measured in airNote 1 to entry: Mass is expressed in kilograms per litre while volume is expressed in litres.3.2reference temperaturetemperature at which the sample “litre weight” shall be reported3.3calibrationset of operations that establishes the relationship between the
23、reference “litre weight in air” of standards and the corresponding “litre weight in air” reading of the instrument4 PrincipleA small portion (typically 1 ml) of the test sample is introduced into a temperature-controlled sample cell. The oscillation frequency is noted and the “litre weight” of the t
24、est sample is calculated using cell constants previously determined by measuring the oscillation frequencies when the cell is filled with calibration media of known litre weight.INTERNATIONAL STANDARD ISO 18301:2014(E) ISO 2014 All rights reserved 1BS ISO 18301:2014ISO 18301:2014(E)5 Apparatus5.1 Di
25、gital density meter, capable, once calibrated, of determining “litre weight” with a resolution of 0,000 1 kg/l or better.A heated injection device is recommended if samples that are solid at room temperature need to be analyzed.5.2 Circulating constant-temperature bath, if required (see 9.1.1), capa
26、ble of maintaining the temperature of the circulating liquid to within 0,05 C of the required temperature.5.3 Calibrated temperature sensor, capable of measuring the temperature of the cell to an accuracy of at least 0,1 C.6 ReagentsWARNING The use of this International Standard might involve hazard
27、ous materials, operations, and equipment. This International Standard does not purport to address all of the safety problems associated with its use. It is the responsibility of the user of this International Standard to establish appropriate health and safety practices and determine the applicabili
28、ty of regulatory limitations prior to use.Unless otherwise stated, use only reagents of recognized analytical grade.6.1 Flushing solvent, any solvent may be used provided it is capable of producing a dry cell and thus acetone is preferred, followed by drying with dry air.6.2 Calibration media, one o
29、r two calibration media are needed to calibrate the cell.They shall be chosen so that their “litre weights” are close to the litre weight of the sample under test. The litre weight of the calibration media shall be traceable to recognized national standards or based on internationally accepted value
30、s.When water is used, the requirements of 6.3 shall be met.6.3 Water, conforming to ISO 3696 grade 2 or better.Prior to use, pass the water through a 0,45 m filter and remove dissolved air by first boiling and then cooling. Once de-aerated, handle the water carefully so as to minimize the amount of
31、air re-dissolved. The “litre weight in air” of water at temperatures from 15 C to 65 C is shown in Table 1.7 SamplingIt is essential that the portion of the sample to be tested is representative of the bulk sample and sample mixing can sometimes be necessary to ensure homogenization prior to subsamp
32、ling.8 Preparation of the test sample and test portionPrepare the sample in accordance with the method given in ISO 661.Samples shall be heated to at least 10 C above their melting points before being introduced into the instrument. Oils and fats which are sufficiently mobile should be mixed by gent
33、le agitation, avoiding the incorporation of air.2 ISO 2014 All rights reservedBS ISO 18301:2014ISO 18301:2014(E)Table 1 Conventional mass per volume (“litre weight in air”) of water at temperatures from 15 C to 65 CTemperatureC“Litre weight in air”wg/mlTemperatureC“Litre weight in air”wg/mlTemperatu
34、reC“Litre weight in air”wg/ml15 0,998 05 35 0,992 98 55 0,984 6516 0,997 89 36 0,992 64 56 0,984 1617 0,997 72 37 0,992 28 57 0,983 6718 0,997 54 38 0,991 92 58 0,983 1719 0,997 35 39 0,991 55 59 0,982 6720 0,997 15 40 0,991 17 60 0,982 1721 0,996 94 41 0,990 79 61 0,981 6522 0,996 72 42 0,990 39 62
35、 0,981 1323 0,996 49 43 0,989 99 63 0,980 6024 0,996 24 44 0,989 58 64 0,980 0625 0,995 99 45 0,989 17 65 0,979 5226 0,995 73 46 0,988 74 - -27 0,995 46 47 0,988 32 - -28 0,995 18 48 0,987 88 - -29 0,994 90 49 0,987 44 - -30 0,994 60 50 0,986 99 - -31 0,994 29 51 0,986 54 - -32 0,993 98 52 0,986 07
36、- -33 0,993 65 53 0,985 61 - -34 0,993 32 54 0,985 13 - -9 Procedure9.1 Apparatus preparation9.1.1 Test temperatureThe sample “litre weight” shall, whenever possible, be determined at the reference temperature.If the density meter is fitted with an integral thermostat, set the cell temperature accor
37、ding to the manufacturers instructions. Otherwise, connect it to the constant-temperature bath. Allow the temperature to stabilize. The manufacturers specified working temperature and pressure ranges for the density meter cell shall not be exceeded. When temperature controlled baths are used, ensure
38、 that the circulating liquid remains clean.9.1.2 Cell cleaningClean and dry the cell using the flushing solvent (6.1) and, if necessary, water (6.3), followed by a water-miscible solvent (6.1) and blow dry with dry air. ISO 2014 All rights reserved 3BS ISO 18301:2014ISO 18301:2014(E)9.2 Apparatus ca
39、libration9.2.1 Density meters shall be calibrated when first installed, or when maintenance has been carried out or the system has been disturbed in any other way. The density meter calibration shall be verified within a period of not more than seven days prior to use.9.2.2 Perform the calibration i
40、n accordance with the manufacturers instructions. Introduce the first calibration medium (6.2) into the cell and allow the cell and its contents to reach temperature equilibrium. Record the oscillation period or the “litre weight in air” reading and the temperature of the cell. Clean the cell in acc
41、ordance with the procedure given in 9.1.2.9.2.3 Introduce the second calibration medium (6.2) into the cell and allow the cell and its contents to reach temperature equilibrium. Record the oscillation period or the “litre weight in air” reading and the temperature of the cell.9.2.4 The cell constant
42、s are calculated automatically by the apparatus.9.2.5 After calibration, clean and dry the cell in accordance with the procedure given in 9.1.29.3 Measurement9.3.1 Check that the density meter reading when the cell is filled with ambient air is within 1 of the last significant digit compared to the
43、reference value achieved during calibration (9.2). If it is not, re-clean and dry the cell and repeat the check. If the reading still differs, recalibrate the density meter.9.3.2 Introduce the test portion of the sample into the cell using a suitable syringe or auto sampler, filling the cell accordi
44、ng to the manufacturers instructions.When testing samples that are solid at room temperature, warm the syringe or auto sampler to a temperature that is 20 C above the melting point of the sample.9.3.3 When using an auto sampler, either run samples in duplicate or introduce check samples in order for
45、 errors due to bubble formation to be detected and the system performance monitored. When making a manual injection, switch on the cell illumination before injecting. Check the cell for bubbles and fill in accordance with the manufacturers instructions. If bubbles are detected, empty and refill the
46、cell and recheck for bubbles. With respect to the viewing and illumination of the cell, refer to the manufacturers recommendations.9.3.4 When the density meter displays a reading which is steady to within 0,1 g/l for “litre weight in air” or to five significant figures for the oscillation period, no
47、te and record the indicated figure and the cell temperature to the nearest 0,1 C.A consistent drift in the oscillation period or “litre weight in air” reading normally indicates that the cell has not reached equilibrium temperature. Random variations in readings normally indicate that air or gas bub
48、bles are present in the cell. In this case, the cell should be recharged with a fresh sample.9.3.5 Clean and dry the cell in accordance with the procedure given in 9.1.2.10 Calculation10.1 If the density meter displays an oscillation period, calculate the “litre weight” of the sample in accordance w
49、ith the manufacturers instructions.4 ISO 2014 All rights reservedBS ISO 18301:2014ISO 18301:2014(E)10.2 If the “litre weight in air” is required at a reference temperature other than that at which it was determined, convert the “litre weight in air” to the litre weight at the reference temperature using the correction factor of 0,000 68 per C. Not more than 3 C difference should be converted by this calculation.Express the “litre weight in air” to the nearest 0,000 1 kg/l at the reference temperature.
