ISO INTERNATIONAL STANDARD 8990 First edition 1994-09-01 Thermal insulation -- Determination of steady-state therma! transmission properties Calibrated and guarded hot box Isolation thermique - Determination des proprietés de transmission thermique en régime stationnaire - Méthodes a la boite chaude gardée et calibrée ISO Reference number ISO 8990:1994(E) Copyright Intemational Organization for Standardization No reproduction or networking permited without license from IHS Not for Resal ISO 8990:1994(E) Contents Page Section 1 General 7 1.1 Scope 1.2 Normative reference 1 1.3 Definitions 2 1.4 Symbols, units and relationships 2 1.5 Principle 2 1.6 Limitations and sources of errors 4 Section 2 Apparatus 8 2.1 Introduction 8 2.2 Design requirements 8 2.3 Metering box 6 2.4 Guard box 9 2.5 Specimen frame 10 2.6 Cold side chamber 10 2.7 Temperature measurements 10 2.8 instrumentation 11 2.9 Performance evaluation and calibration 11 Section 3 Test procedure 13 3.1 Introduction 13 3.2 Conditioning of specimen 13 3.3 Specimen selection and mounting 13 3.4 Test conditions 14 3.5 Measurement periods 14 3.6 Calculations 14 3.7 Test report 14 ISO1994 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 International Organization for Standardization Case Postale 56: CH-1211 Geneve 20 : Switzerland Printed in Switzerland ii No reproduction or networking permitted without license from IHS Not for Resale @ISO ISO 8990:1994(E) Annexes A Heat transfer at surfaces and environmental temperatures 16 B Bibliography 19 ili No reproduction or networking permited without license from IHS Not for Resale