1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS ISO 14934-2:2013Fire tests Calibration and use of heat flux metersPart 2: Primary calibration methodsBS ISO 14934-2:2013 BRITISH STANDARDNational forewordThis British Standard
2、 is the UK implementation of ISO 14934-2:2013.The UK participation in its preparation was entrusted to Technical Committee FSH/21, Reaction to fire tests.A list of organizations represented on this committee can be obtained on request to its secretary.This publication does not purport to include all
3、 the necessary provi-sions of a contract. Users are responsible for its correct application. The British Standards Institution 2013. Published by BSI Standards Limited 2013 ISBN 978 0 580 71902 8 ICS 13.220.40; 13.220.50 Compliance with a British Standard cannot confer immunity from legal obligation
4、s.This British Standard was published under the authority of the Standards Policy and Strategy Committee on 30 April 2013.Amendments issued since publicationDate Text affectedBS ISO 14934-2:2013 ISO 2013Fire tests Calibration and use of heat flux meters Part 2: Primary calibration methodsEssais au f
5、eu talonnage et utilisation des appareils de mesure du flux thermique Partie 2: Mthodes dtalonnage primaireINTERNATIONAL STANDARDISO14934-2Second edition2013-03-15Reference numberISO 14934-2:2013(E)BS ISO 14934-2:2013ISO 14934-2:2013(E)ii ISO 2013 All rights reservedCOPYRIGHT PROTECTED DOCUMENT ISO
6、2013All 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. Permission can be reque
7、sted 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 14934-2:2013ISO 14934-2:2013(E) ISO 2013
8、All rights reserved iiiContents PageForeword vIntroduction vi1 Scope . 12 Normative references 13 Terms and definitions . 14 Principles . 14.1 General principles 14.2 Principle of the vacuum black-body cavity (VBBC) method (method 1) 14.3 Principle of the spherical black-body cavity method (method 2
9、). 24.4 Principle of the variable temperature black-body (VTBB) method (method 3) 25 Suitability of a gauge for calibration . 25.1 Types of heat flux meters . 25.2 Design of heat flux meters . 35.3 Measuring range 35.4 Status of heat flux meter prior to calibration . 36 Vacuum black-body cavity (VBB
10、C) method (method 1) . 36.1 Apparatus 36.2 Operating procedure 66.3 Uncertainty . 67 Spherical black-body cavity method (method 2) 77.1 Apparatus 77.2 Operating procedure . 117.3 Uncertainty 118 Variable-temperature black-body (VTBB) method (method 3) .148.1 Apparatus . 148.2 Operating procedure . 1
11、68.3 Uncertainty 189 Number of calibration levels .1910 Expression of results .2011 Calibration report 21Annex A (normative) Operating procedure for vacuum black-body cavity method (VBBC) (method 1) .22Annex B (normative) Calculating the irradiance from the vacuum black-body cavity (VBBC) to the hea
12、t flux meter 24Annex C (informative) Examples of computer screens for calculating the irradiance from the vacuum black-body cavity (VBBC) .27Annex D (normative) Operating procedure for spherical black-body cavity method (method 2) .29Annex E (normative) Calculating the irradiance from the spherical
13、black-body cavity to the heat flux meter 31Annex F (normative) Drawings for the fixed and movable cooler to the spherical black-body cavity .34Annex G (informative) Guidance notes for operators using the spherical black-body cavity method .38Annex H (normative) Electrical substitution radiometer (ES
14、R) operating procedure .39Annex I (normative) Procedure for heat flux meter calibration using the 25-mm VTBB method BS ISO 14934-2:2013ISO 14934-2:2013(E)iv ISO 2013 All rights reserved(method 3) .41Annex J (normative) Data reduction procedure for the VTBB method (method 3) .43Annex K (informative)
15、Precision of calibration .45Bibliography .46BS ISO 14934-2:2013ISO 14934-2:2013(E)ForewordISO (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
16、 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 organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborate
17、s 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 ISO/IEC Directives, Part 2.The main task of technical committees is to prepare International Standards.
18、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 the member bodies casting a vote.Attention is drawn to the possibility that some of the elements of this do
19、cument may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights.ISO 14934-2 was prepared by Technical Committee ISO/TC 92, Fire safety, Subcommittee SC 1, Fire initiation and growth.This second edition cancels and replaces the first edition
20、 (ISO 14934-2:2006), which has been technically revised.ISO 14934 consists of the following parts, under the general title Fire tests Calibration and use of heat flux meters: Part 1: General principles Part 2: Primary calibration methods Part 3: Secondary calibration method Part 4: Guidance on the u
21、se of heat flux meters in fire tests ISO 2013 All rights reserved vBS ISO 14934-2:2013ISO 14934-2:2013(E)IntroductionIn many fire test methods, the radiation level is specified and, therefore, it is of great importance that the radiant heat flux is well defined and measured with sufficient accuracy.
22、 Radiant heat transfer is also the dominant mode of heat transfer in most real fires.In practice, radiant heat flux is usually measured with so-called total heat flux meters of the Schmidt-Boelter (thermopile) or Gardon (foil) type. Such meters register the combined heat flux by radiation and convec
23、tion to a cooled surface. The contribution to the heat transfer by convection depends mainly on the temperature difference between the surrounding gases and the sensing surface and on the velocity of the surrounding gases. It will, however, also depend on size and shape of the heat flux meter, its o
24、rientation and on its temperature level, which is near the cooling water temperature. In many practical situations in fire testing, the contribution due to convection to the sensing surface of the instrument can amount to 25 % of the radiant heat flux. Thus it is always necessary to determine and co
25、ntrol this part.To determine the fraction of total heat flux due to radiation, a calibration scheme is developed where primary calibration is performed on two different types of heat flux meters: (1) a total hemispherical radiometer sensitive to radiation only, and (2) a total heat flux meter, (most
26、 frequently used) sensitive to both radiant heat transfer and to convective heat transfer. A comparison of measurements between the two types of meters in secondary (or transfer) calibration methods allows a characterization of the influence of convection in the method. Where possible, in all calibr
27、ations and measurements of radiative heat flux, the uncertainty calculations should include the uncertainty associated with removing the convective component. For secondary calibration methods, a combined use of hemispherical radiometers and total heat flux meters makes it possible to estimate the c
28、onvection contribution. The same arrangement can be used in calibration of fire test methods as well.Primary calibration is performed in a black-body cavity under conditions where the convective part of the heat transfer can be neglected or controlled. One such apparatus is an evacuated black-body f
29、acility with the unique characteristic of negligible convection and conduction effects described in this document as the vacuum black-body cavity (VBBC) method (method 1). Other (non-evacuated) black-body facilities can also be suitable as primary heat sources for calibration, providing they are ful
30、ly characterized, particularly in terms of any convection effects on the sensing surface of the heat flux meter being calibrated. One such facility, described in this document as the spherical black-body cavity method (method 2), is a furnace with an orifice pointing downwards to minimize the convec
31、tion. Another is the variable temperature black-body method (method 3) in which the effect of the convective component is minimized by the adoption of a substitution procedure in which the heat flux meter to be calibrated is compared with a primary standard radiometer. Under such conditions the conv
32、ective effect for each measurement can be asumed to be of a similar magnitude.NOTE Schmidt-Boelter meters and Gardon meters are examples of suitable products available commercially. This information is given for the convenience of users of this part of ISO 14934 and does not constitute an endorsemen
33、t by ISO of this product.vi ISO 2013 All rights reservedBS ISO 14934-2:2013Fire tests Calibration and use of heat flux meters Part 2: Primary calibration methods1 ScopeThis part of ISO 14934 describes three methods for calibration of total hemispherical radiometers and total heat flux meters that ar
34、e exposed to a well-defined radiation from a radiant heat source. The equipment is designed to minimize influences due to convective heat transfer during calibration. It is important to note that when the instruments are used in practice they measure a combination of radiant and convective heat tran
35、sfers. The latter will depend on the design of the heat flux meter, the orientation, local temperature and flow conditions, and on the temperature of the cooling water.2 Normative referencesThe following documents, in whole or in part, are normatively referenced in this document and are indispensabl
36、e for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.ISO 13943, Fire safety VocabularyISO 14934-1, Fire tests Calibration and use of heat flux meters Part 1: General princ
37、iplesIEC 60584-2, Thermocouples Part 2: TolerancesISO/IEC Guide 98-3, Uncertainty of measurement Part 3: Guide to the expression of uncertainty in measurement (GUM:1995)ISO/IEC Guide 99, International vocabulary of metrology Basic and general concepts and associated terms (VIM)3 Terms and definition
38、sFor the purposes of this document, the terms and definitions given in ISO 13943, ISO 14934-1, ISO/IEC Guide 98-3 and ISO/IEC Guide 99 apply.4 Principles4.1 General principlesCalibration of heat flux meters (total hemispherical radiometers and total heat flux meters) is performed with a black-body r
39、adiant heat source.4.2 Principle of the vacuum black-body cavity (VBBC) method (method 1)This method is used to calibrate heat flux meters between 2 kW/m2and 70 kW/m2. It is designed to accept total heat flux meters or total hemispherical radiometers with a housing diameter of up to 50 mm. These may
40、 have pipes for water or/and air that are located axially. Calibration of heat flux meters consists of reading the output voltage of total heat flux meters or total hemispherical radiometers when irradiated by a traceable black-body radiant source operating under vacuum. By lowering the absolute pre
41、ssure in the black-body cavity to between 0,5 Pa and 2 Pa, the convective heat transfer is significantly INTERNATIONAL STANDARD ISO 14934-2:2013(E) ISO 2013 All rights reserved 1BS ISO 14934-2:2013ISO 14934-2:2013(E)reduced. Heat flux meters to be calibrated are fixed on a support and form a part of
42、 the closed system. The operating procedure is given in Annex A. The relation between the furnace and the irradiance to the heat flux meter is given in Annex B. Examples of computer screens are given in Annex C.4.3 Principle of the spherical black-body cavity method (method 2)This method is used to
43、calibrate heat flux meters between 2 kW/m2and 70 kW/m2. A black-body radiant heat source designed as a spherical furnace with an aperture at the bottom is used. The temperature level of the furnace is controlled with high precision and is very uniform inside the furnace assuring a high precision of
44、the radiant heat level.Heat flux meters to be calibrated are inserted through the aperture at the bottom of the furnace with the sensing surface of the heat flux meter oriented horizontally. The influence of convection is thus reduced to a minimum. The heat flux meter sees nothing but the controlled
45、 environment of the black-body emitter. The radiation level of this black-body emitter depends primarily on the measured temperature making it traceable to international thermal calibration standards.The accuracy of the method depends on the design of the test apparatus. The operating procedure is g
46、iven in Annex D. The relation between the furnace temperature and the irradiance to the heat flux meter is described in Annex E. The limits of errors assume that the apparatus is constructed according to the figures in Annex F. Guidance notes for operators are given in Annex G.4.4 Principle of the v
47、ariable temperature black-body (VTBB) method (method 3)The technique uses the principle of electrical substitution radiometry to calibrate heat flux sensors up to 50 kW/m2. The sensors are calibrated with reference to a room-temperature electrical substitution radiometer whose calibration is traceab
48、le to a primary standard high accuracy cryogenic radiometer (HACR). This is a standard for optical radiation power and is supported through a chain of independent calibrations.The calibration uses the 25 mm cavity diameter variable temperature black-body (VTBB) facility as broadband radiant source.
49、The VTBB consists of a dual-cavity, electrically heated graphite tube. The black-body temperature is controlled and is stable within 0,1 K of the set value.The heat flux sensor to be calibrated and the reference standard radiometer are located at a fixed distance away from the black-body aperture, depending on the heat flux level. The variation in the incident heat flux level at the sensor location is obtained by varying the VTBB temperature. The operating procedure for electrical substitution radiometer is given in Annex H. The c
