1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS EN 16242:2012Conservation of culturalheritage Procedures andinstruments for measuringhumidity in the air andmoisture exchanges betweenair and cultural propertyBS EN 16242:2012
2、 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of EN 16242:2012. The UK participation in its preparation was entrusted to TechnicalCommittee B/560, Conservation of tangible cultural heritage. A list of organizations represented on this committee can be obtained on r
3、equest to its secretary.This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. The British Standards Institution 2012. Published by BSI Standards Limited 2012.ISBN 978 0 580 74014 5 ICS 97.195 Compliance with a Brit
4、ish Standard cannot confer immunity from legal obligations.This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 December 2012.Amendments issued since publicationDate T e x t a f f e c t e dBS EN 16242:2012EUROPEAN STANDARD NORME EUROPENNE EUROP
5、ISCHE NORM EN 16242 November 2012 ICS 97.195 English Version Conservation of cultural heritage - Procedures and instruments for measuring humidity in the air and moisture exchanges between air and cultural property Conservation des biens culturels - Modes opratoires et instruments de mesure de lhumi
6、dit de lair et des changes dhumidit entre lair et les biens culturels Erhaltung des kulturellen Erbes - Verfahren und Gerte zur Messung der Luftfeuchte und des Austausches von Feuchtigkeit zwischen Luft und Kulturgut This European Standard was approved by CEN on 8 September 2012. CEN members are bou
7、nd to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the C
8、EN-CENELEC Management Centre or to any CEN member. This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre
9、has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
10、Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: Avenue Marnix 17, B-1000 Brussels 2012
11、 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 16242:2012: EBS EN 16242:2012EN 16242:2012 (E) 2 Contents Page Foreword 3Introduction .41 Scope 52 Normative references 53 Terms and definitions .54 Quantities characterising humidit
12、y in air 85 Considerations and recommendations related to measuring methods 95.1 Considerations .95.2 Recommendations 106 Main features of the hygrometers . 116.1 Chilled-mirror dew-point hygrometer . 116.2 Electronic psychrometer 126.3 Electronic hygrometer with a capacitive sensor . 136.4 Electron
13、ic hygrometer with a resistive sensor 136.5 Hair hygrometer/hygrograph . 147 Instrument calibration 14Annex A (informative) Formulae for calculating relative humidity and related variables 16A.1 Instruments: Psychrometer, barometer Parameters: air temperature t (C), wet bulb air temperature tw(C), p
14、 (hPa) . 16A.2 Instruments: RH hygrometer, thermometer, barometer - Parameters: t, RH, p . 17A.3 Instruments: Dew-point hygrometer, thermometer, barometer - Parameters: t,: td, p 18Annex B (informative) Examples for indoor climate measurements 19B.1 Recognising the penetration and spread of external
15、 air across a room 19B.2 Recognising if wall dampness is associated to condensation or evaporation . 20B.3 External dampness entering a room shown with a mixing ratio plot 20Annex C (informative) Instrumental errors 22C.1 Psychrometer: errors in the various hygrometric variables generated by an erro
16、r of 0,1 C in a temperature reading 22C.2 Psychrometer: error in determining the relative humidity due to pressure change . 23C.3 Error due to a thermal inertia of a case, a probe or a shield 23C.4 Typical non-linearity and hysteresis of the hair hygrometer . 24C.4.1 Hair non-linearity and hysteresi
17、s 24C.4.2 Linear and non-linear scales . 25Bibliography . 28BS EN 16242:2012EN 16242:2012 (E) 3 Foreword This document (EN 16242:2012) has been prepared by Technical Committee CEN/TC 346 “Conservation of cultural heritage”, the secretariat of which is held by UNI. This European Standard shall be giv
18、en the status of a national standard, either by publication of an identical text or by endorsement, at the latest by May 2013, and conflicting national standards shall be withdrawn at the latest by May 2013. Attention is drawn to the possibility that some of the elements of this document may be the
19、subject of patent rights. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent rights. According to the CEN/CENELEC Internal Regulations, the national standards organisations of the following countries are bound to implement this European Standard: Austria, Belgium
20、, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerla
21、nd, Turkey and the United Kingdom. BS EN 16242:2012EN 16242:2012 (E) 4 Introduction Humidity plays a key role in the conservation of cultural heritage because most materials and/or deterioration mechanisms are directly or indirectly affected by humidity levels or changes. This European Standard is a
22、 guide intended to assist in providing an acceptable environment for cultural heritage objects. Humidity in air, expressed in a number of ways, is an important aspect of that environment. Therefore, the control of levels and variability of humidity reduces the risk of deterioration and is an importa
23、nt preventive measure, minimising the need for future conservation interventions. This European Standard is a guide to specifying adequate procedures for measuring humidity in air and the minimum characteristics of instruments for such measurements so that they are carried out to an appropriate leve
24、l of accuracy. Although standards exist for measuring humidity in air in other fields like meteorology or ergonomics of thermal environments, this standard focuses on the specific requirements of cultural objects. This document is one of the series of European Standards intended for use in the study
25、 of environments for cultural property. BS EN 16242:2012EN 16242:2012 (E) 5 1 Scope This European Standard gives guidance and specifies procedures and instruments for the measurement of relative humidity (RH) in air, in outdoor or indoor environments. It indicates how RH can be directly measured or
26、how it can be calculated from air temperature, wet-bulb temperature and dew-point temperature. This standard contains recommendations for accurate measurements of ambient conditions and moisture exchanges between air and cultural heritage objects. It is addressed to anyone in charge of environmental
27、 diagnosis, conservation or maintenance of buildings, collections or single objects. 2 Normative references The 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 u
28、ndated references, the latest edition of the referenced document (including any amendments) applies. EN 15757:2010, Conservation of Cultural Property - Specifications for temperature and relative humidity to limit climate-induced mechanical damage in organic hygroscopic materials EN 15758:2010, Cons
29、ervation of Cultural Property - Procedures and instruments for measuring temperatures of the air and of the surfaces of objects EN 60751, Industrial platinum resistance thermometers and platinum temperature sensors (IEC 60751) EN ISO/IEC 17025, General requirements for the competence of testing and
30、calibration laboratories (ISO/IEC 17025) ISO/IEC Guide 98-3 Uncertainty of measurement - Part 3: Guide to the expression of uncertainty in measurement (GUM) 3 Terms and definitions For the purposes of this document, the terms and definitions given in EN 15758:2010 and the following apply. 3.1 absolu
31、te humidity (AH) volume density of water vapour, i.e. the mass of vapour contained in the unit volume of moist air AH =mvV, expressed in g/m3Note 1 to entry: This volume density is also noted v (v for volume) 3.2 atmospheric (or barometric) pressure (p) pressure is the force per unit area exerted by
32、 the air column above the measuring point, expressed in hPa (hectopascal) Note 1 to entry: 1 hPa = 1 mbar (millibar) 3.3 barometer instrument for measuring atmospheric pressure BS EN 16242:2012EN 16242:2012 (E) 6 3.4 dew-point hygrometer instrument for measuring the temperature at which a cooled par
33、cel of air becomes saturated with water vapour 3.5 dew-point temperature (DP) temperature to which air is cooled at constant pressure and constant water vapour content in order for saturation to occur Note 1 to entry: This is expressed in degrees Celsius (C). EN 15758: 2010 3.6 dry air atmospheric a
34、ir without water vapour 3.7 dry-bulb temperature (T, t) actual air temperature. In a psychrometer, the temperature reached by the thermometer having the dry bulb Note 1 to entry: Capital T is used when the measurement is expressed in Kelvin (K); lowercase t when expressed in degrees Celsius (C). 3.8
35、 equilibrium moisture content (EMC) moisture content at which a material neither loses nor gains moisture from the surrounding atmosphere at given relative humidity and temperature levels. Expressed in g/kg as the ratio of the mass of water mwcontained in the material and the dry mass mdmof the same
36、 material, i.e.: EMC = dmwmm3.9 frost-point temperature temperature to which moist air must be cooled, at constant pressure and humidity mixing ratio, in order that it shall be saturated with respect to ice, expressed in degrees Celsius (C) 3.10 hygrograph instrument for measuring relative humidity
37、(see hygrometer) and recording over time Note 1 to entry: Generally, a mechanically or electrically driven drum supporting a strip chart with RH graduation where an ink pen traces a time plot of the ambient humidity. 3.11 hygrometer instrument measuring relative humidity Note 1 to entry: It generall
38、y comprises a sensor, which is set in equilibrium with the air, and a system that transforms the signal from the sensor into humidity readings. 3.12 mixing ratio or humidity mixing ratio (MR) ratio of the mass of water vapour mvto the mass of dry air ma, i.e. avmmMR = , expressed in g/kg3.13 moist a
39、ir mixture of dry air and water vapour BS EN 16242:2012EN 16242:2012 (E) 7 3.14 psychrometer instrument for measuring the dry- and wet-bulb temperatures to calculate relative humidity and other related variables Note 1 to entry: It consists of two identical thermometers, one of which is sheathed in
40、wet wicking, and a fan to ensure their ventilation at a constant velocity in order to reach equilibrium with air. Thermometer readings are expressed in degrees Celsius (C). Some electronic instruments provide readings of relative humidity (%), dew point (C) and other related variables. 3.15 relative
41、 humidity (RH) ratio of the actual vapour pressure of the air to the saturation vapour pressure SOURCE: EN 15757:2010 3.16 measuring range interval of values that are intended to be measured, or that are potentially measurable, or that have been measured, specified by their upper and lower limits 3.
42、17 repeatability ability of the measuring instrument to reproduce the same output when successively measuring the same value of the air or the surface under investigation, taken under the same conditions Note 1 to entry: This is expressed as percent of the range. SOURCE: EN 15758:2010 3.18 resolutio
43、n smallest difference between indications of a displaying device that can be meaningfully distinguished 3.19 response time time interval between the instant when the parameter under investigation is subjected to a specified abrupt change and the instant when the response reaches and remains within s
44、pecified limits around its final steady value Note 1 to entry: The response time is typically expressed as the time needed to reach 63,2 % of the final value and in this case is called time constant, or 90 % or 95 % of it. The 90 % response time is 2,3 times longer than the time constant and the 95
45、% response time is three times longer. The response time is independent of the span of the output change. SOURCE: EN 15758:2010 3.20 saturation vapour pressure (esat(t) maximum pressure of the water vapour in equilibrium with plane surface of pure water, expressed in hPa (hectopascal) 3.21 sensor de
46、vice that senses either an absolute value or a change in a physical quantity and converts them into a useful signal for an information-gathering system BS EN 16242:2012EN 16242:2012 (E) 8 3.22 thermometer instrument to measure temperature which comprises a sensor which is placed in thermal equilibri
47、um with the air (if it measures the air temperature) or the surface, sometimes a probe that contains and protects the sensor, and a system that transforms the input from the sensor into an output expressed in degrees Celsius (C) SOURCE: EN 15758:2010 3.23 time constant time interval between the inst
48、ant when the air, or the surface temperature, is subjected to a specified abrupt change and the instant when the response reaches (1 1/e) x 100 = 63,2 % and remains within specified limits around its final steady value Note 1 to entry: See also response time. SOURCE: EN 15758:2010 3.24 time stabilit
49、y rate at which characteristics change in the course of time Note 1 to entry: It is often expressed in terms of a percent change of the response per year (% / year). 3.25 surface temperature (ts) temperature of a given surface of an object Note 1 to entry: This can be measured with contact thermometers, quasi-contact total radiation thermometers or remote infrared thermometers. The surface temperature is generally different from the air temperature, and varies between differ
