EN 14114:2002
(Main)Hygrothermal performance of building equipment and industrial installations - Calculation of water vapour diffusion - Cold pipe insulation systems
Hygrothermal performance of building equipment and industrial installations - Calculation of water vapour diffusion - Cold pipe insulation systems
This standard specifies a method to calculate the density of water vapour flow rate for cold pipes, and the total amount of water absorption over time. This calculation method applies only when the water vapour partial pressure difference is perpendicular to the axis of the pipes and the water vapour partial pressure is constant at all points equidistant from the axis of the pipe.
Wärme- und feuchtetechnisches Verhalten von haus- und betriebstechnischen Anlagen - Berechnung der Wasserdampfdiffusion - Dämmung von Kälteleitungen
Diese Norm beschreibt Verfahren zur Berechnung der Wasserdampf-Diffusionsstromdichte für kälteleitungen und der Gesamtmenge an Wasserabsorption über die Zeit. Dieses Berechnungsverfahren gilt nur, wenn die Wasserdampfteildruckdifferenz senkrecht zur Rohrachse auftritt und der Wasserdampfteildruck an allen Punkten, die von der Rohrachse einen gleichen Abstand haben, konstant ist.
Performance hygrothermique des équipements de bâtiments et installations industrielles - Calcul de la diffusion de vapeur d'eau - Systèmes d'isolation de tuyauteries froides
La présente norme donne une méthode permettant de calculer la densité du flux de vapeur deau dans le cas des tuyauteries froides ainsi que la quantité totale d'eau absorbée en fonction du temps. Cette méthode de calcul ne s'applique que lorsque la différence de pression partielle de vapeur d'eau est perpendiculaire à l'axe du tuyau et que la pression partielle de vapeur d'eau est constante en tout point équidistant de l'axe du tuyau.
Higrotermalno obnašanje opreme stavb in industrijskih inštalacij - Izračun difuzije vodne pare - Sistemi za izoliranje hladnih cevi
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2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Wärme- und feuchtetechnisches Verhalten von haus- und betriebstechnischen Anlagen - Berechnung der Wasserdampfdiffusion - Dämmung von KälteleitungenPerformance hygrothermique des équipements de bâtiments et installations industrielles - Calcul de la diffusion de vapeur d'eau - Systemes d'isolation de tuyauteries froidesHygrothermal performance of building equipment and industrial installations - Calculation of water vapour diffusion - Cold pipe insulation systems91.120.10Toplotna izolacija stavbThermal insulationICS:Ta slovenski standard je istoveten z:EN 14114:2002SIST EN 14114:2002en01-november-2002SIST EN 14114:2002SLOVENSKI
STANDARD
EUROPEAN STANDARDNORME EUROPÉENNEEUROPÄISCHE NORMEN 14114March 2002ICS 91.120.10English versionHygrothermal performance of building equipment and industrialinstallations - Calculation of water vapour diffusion - Cold pipeinsulation systemsPerformance hygrothermique des équipements debâtiments et installations industrielles - Calcul de ladiffusion de vapeur d'eau - Systèmes d'isolation detuyauteries froidesWärme- und feuchtetechnisches Verhalten von haus- undbetriebstechnischen Anlagen - Berechnung derWasserdampfdiffusion - Dämmung von KälteleitungenThis European Standard was approved by CEN on 28 June 2001.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the 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 translationunder the responsibility of a CEN member into its own language and notified to the Management Centre has the same status as the officialversions.CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece,Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMITÉ EUROPÉEN DE NORMALISATIONEUROPÄISCHES KOMITEE FÜR NORMUNGManagement Centre: rue de Stassart, 36
B-1050 Brussels© 2002 CENAll rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 14114:2002 ESIST EN 14114:2002
Examples14Annex B (informative)
Experimental determination of the evaporation rate from the surfaceof a wet wick fabric16Bibliography18SIST EN 14114:2002
Thisflow of water vapour leads to an interstitial condensation in the insulation layer and/or dewformation on the surface of the pipe itself.
Interstitial condensation may cause the insulationmaterial to deteriorate and dew formation on the surface of a metal pipe may cause corrosionover time.
If the temperature is below 0 C ice will be formed and the methods of thisstandard will not apply.In periods where the dew point of the ambient air is higher than the temperature of the outersurface of the insulation surface condensation will occur.
This is dealt with in EN ISO 12241.Different measures are available to control water vapour transfer and reduce the amount ofcondensation.
The following are normally applied:a) Installation of a vapour retarder;b) Use of insulation materials with a high water vapour resistance factor (low permeability);c) Use of a vapour retarder and a capillary active fabric to continuously remove condensedwater from the pipe surface to the environment.Which protection measure is chosen depends on the ambient climate, the temperature of themedium in the pipe and the water vapour diffusion resistance of the insulation layer.
Thesuccess of any system is strongly dependent on workmanship and maintenance.
In any caseanti-corrosion measures should be applied to a metal pipe in severe conditions.The expected economic lifetime of an insulation system, assuming a maximum acceptableaccumulated moisture content, can be calculated using the methods in this standard.1 ScopeThis standard specifies a method to calculate the density of water vapour flow rate in cold pipeinsulation systems, and the total amount of water diffused into the insulation over time.
Thiscalculation method presupposes that water vapour can only migrate into the insulation system bydiffusion, with no contribution from airflow.
It also assumes the use of homogeneous, isotropicinsulation materials so that the water vapour partial pressure is constant at all points equidistantfrom the axis of the pipe.The standard is applicable when the temperature of the medium in the pipe is above 0 C. Itapplies to pipes inside buildings as well as in the open air.SIST EN 14114:2002
=1, and an area of
Dj which has the samediffusion resistance as the layer j with
= jNOTE
See Equation (18).SIST EN 14114:2002
= 461,5J/(kgK)Tthermodynamic temperatureKZPwater vapour resistance of insulation system per linear metreof pipemsPa/kgZjwater vapour resistance of jth layer of an insulation system perlinear metre of pipemsPa/kgZf1water vapour resistance of one thin foil, cladding or skin perlinear metre of pipe.msPa/kgdthickness of an insulation layermfeevaporation factorkg/(m2sPa)gwater vapour flow rate within the insulation per linear metreof pipekg/(ms)gcrate of condensation per linear metre of pipekg/(m·s)geevaporation rate per linear metre of pipekg/(ms)hcconvection heat transfer coefficientW/(m2·K)ppartial water vapour pressurePapapartial water vapour pressure of airPapsatsaturated water vapour pressurePasdwater vapour diffusion equivalent air layer thicknessmsdfwater vapour diffusion equivalent air layer thickness of foilsmtperiod of calculation (month or year)month, yearxdistancemwater vapour permeabilitykg/(msPa)0water vapour permeability of airkg/(msPa)water vapour resistance factor-d,jcorrected water vapour diffusion equivalent air layer thicknessof layer jmjd,~total corrected water vapour diffusion equivalent air layerthickness from surface of cold pipe to the outside of layer jm0temperature of the medium in the pipeCNOTE
For practical reasons, hours or days are often used instead of seconds as time units.SIST EN 14114:2002
is the water vapour permeability of the material.The total moisture uptake during a period, G, is given by:tgGtd0(2)In calculations the diffusion resistance factor, , is commonly used instead of the permeability0(3)where 0 is the water vapour permeability of still air, which can be calculated from:81,1v00273083,0TPTRP(4)For approximate calculations, 0 can be assumed to be constant in the temperature range underconsideration; the following value can therefore be used:0 = 2,0
10-10(5)4.2 Homogeneous insulationIn the case of a cold pipe with a single homogeneous layer of insulation, the density of watervapour flow per metre of an insulated cold pipe is given by replacing the differentialexpression by the vapour pressure difference in Equation (1):P0sata)(Zppg(6)wherepa is the vapour pressure of the ambient air, in Pa;psat(0) is the saturation vapour pressure at the outside surface of the pipe, in Pa;ZP
is the water vapour resistance per linear metre of the pipe insulation, inmsPa/kg, defined by Equation (7):SIST EN 14114:2002
See Example A.2.If the outer layer, n, is a vapour retarder jacket, foil or skin, with negligible thickness, but withlarge water vapour diffusion-equivalent air layer thickness sdf, the water vapour resistance ofthe retarder will be:nnnDssDZdf0df02 211(11)The water vapour resistance of the whole system is then:njjnjjDsDDZdf1110P2ln21(12)SIST EN 14114:2002
is the density of air = 1,205 kg/m3 at 20 C;cp
is the specific heat capacity at constant pressure of air = 1005 J/(kgK) at20 C.NOTE
A method of measurement is given in Annex B. Further information regarding Equation (15)is to be found in reference [5] in the Bibliography.For horizontal and vertical pipes in still air hc =10 W/(m2K), giving fe = 6×10-8 kg/(m2·s·Pa).The total water uptake over a time, t, is then given by:ttAppfZppG0eaasateP0satad))(()((16)5 Boundary conditionsSIST EN 14114:2002
The vapour pressure at the surface shall be taken as the saturated vapour pressure atthat temperature, i.e. a relative humidity of 1,0.b) Ambient airOutside buildings, use either the annual mean temperature and vapour pressure or the monthlymean temperature and vapour pressure of the warmest month.Inside buildings, use the temperature and vapour pressure representative of the use of thebuilding in the warmest month of the year.
Methods for deriving internal conditions are givenin EN ISO 13788.NOTE
Use of the monthly mean vapour pressure gives results which are on the safe side.6 Calculation procedure6.1 GeneralThe equations given in Clause 4 allow the calculation of the total amount of water condensingwithin the cold pipe insulation and determination of whether condensation occurs within theinsulation material or only on the pipe surface.For the evaluation of the amount of water vapour transporte
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