1、STD-CEN EN 12213-ENGL 1778 = 3qOq589 OL7LO 77 RATIFIED EUROPEAN TEXT EN122 13: 1998 European Standards only exist formally as national transpositions (i.e. a BS EN for the UK) of a commonly agreed “ratified“ text. This document is a ratified text which will shortly be published as a BS EN. It is bei
2、ng made available in advance of its formal publication to give interested parties early access to the technical information which the BS EN will contain. When the BS EN is formally published it will be supplied to you autoinatically, without any additional charge. Purchasers of this ratified text sh
3、ould be aware of the following limitations when using the document. O The BS EN may contain additional information in the national foreword or national annex, O Full rights conferred by compliance with the standard may only be granted by reference to the formal national transposition of the text as
4、a BS EN. This ratified text was approved by CENKENELEC in its three official languages on the date given below. Under CENKENELEC rules, BSI is obliged to publish its national transposition within six months of this date. This ratified text was approved on 1998-09-04 1 NO COPYING WITHOUT BSI PERMISSI
5、ON EXCEPT AS PERMITTED BY COPRIGK LAW EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 12213 November 1998 ICs 27.200 Descriptors: pressure vessels, cryogeny, definitions, tests, estimation, characteristics, thermal insulation, testing conditions English version Cryogenic vessels - Methods for p
6、erformance evaluation of thermal insulation Rcipients cryogniques - Mthodes d8valuation de la performance de lisolation thermique Ktyo-Behlter - Verfahren zur Bewertung des Wnnedmmvengens This European Standard was approved by CEN on 4 September 1998. GEN members are bound to comply with the CENICEN
7、ELEC Internal Regulations which stipulale 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 Central Secretariat or to any
8、CEN member. This European Standard exists in three official versions (English. French, Geman). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the official versions. CEN
9、members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland. France. Germany, Greece, Iceland. Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal. Spain. Sweden, Switzeriand and United Kingdom. EUROPEAN COMMiTEE FOR STANDARDIZATION COMIT EUROPEEN DE NORMALI
10、SATION EUROPISCHES KOMITEE FR NORMUNG Central Secretariat: rue de Sassewt, 36 E1050 Brussela 0 1998 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 122131998 E STD-CEN EN 12213-ENGL 1998 34U4589 0188712 b4T Page 2 EN 12213:1998 Con
11、tents Foreword 3 Introduction 4 1 Scope 4 2 Definitions . 6 3 General conditions for all methods . 7 4 Measuring the heat leak by the loss of product method . 8 4.1 General 8 4.2 Test procedure . 9 4.3 Determination of the heat leak in units of energy per unit time . 9 4.4 5 6 6.1 6.2 6.3 7 Test rep
12、ort . 13 8 Bibliography . 13 Annex A (normative) Conversion of measured volumetric gaseous flow to mass flow 14 Annex B (normative) Correction of measured mass flow rate with regard to deviation from reference conditions . 15 Annex C (normative) Equivalent loss determination, for product other than
13、the test product 20 Determination of the heat leak as a percentage of product lost per 24 h 10 Determination of the holding time (open system) in days from heat leak data 10 Holding times for closed systems . 10 Determination of the equilibrium holding time from heat leak data 10 Determination of th
14、e optimum equilibrium holding time from heat leak data . 11 Static experimental holding time . 12 - STD-CEN EN 12213-ENGL 2778 E 3Li04587 0188713 58b Page 3 EN 12213:1998 Foreword This European Standard has been prepared by Technical Committee CENTTC 268 Cryogenic vessels“, the secretariat of which
15、is held by AFNOR. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by May 1999, and conflicting national standards shall be withdrawn at the latest by May 1999. This European Standard has been prepare
16、d under a mandate given to CEN by the European Commission and the European Free Trade Association. This European Standard is considered to be a supporting standard to those application and product standards which in themselves support an essential safety requirement of a New Approach Directive and w
17、hich make reference to this European Standard. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Irela
18、nd, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom. STD-CEN EN L2213-ENGL 1998 II 3404589 0188714 Li12 II Page 4 EN 12213:1998 Introduction Traditionally in Europe, there have been different ways of defining the insulation perormance. A requiremen
19、t exists therefore to harmonise such methods of evaluating insulation performance for different cryogenic vessels. To held the understanding of this standard, see the logic diagram in figure I. 1 scope This standard defines a pratica1 method for determining the heat leak performance of cryogenic ves
20、sels. The methods include measurement on both open and closed systems. This standard neither specify the requirement levels for insulation performance nor when the methodology defined is applied. These requirements may be defined in design or operational standardshegulations. STD.CEN EN L2213-EFJGL
21、1778 340Ll589 OLA8715 359 z w Il- I r 2 Definitions For the purpose of this standard, the following definitions apply : 2.1 open system During test, a system is considered open when it is kept at a constant pressure (e.g. atmospheric pressure) and when the gas produced by the evaporation of the test
22、 fluid is continuously released to atmosphere. 2.2 closed system During test, a system is considered closed when the mass of the contents is kept constant with no input or output of product. 2.3 heat leak performance The quantity of heat transferred per unit time from the ambient air to the contents
23、 of the inner vessel. NOTE : In an open system the heat leak causes a loss of product. In a closed system it causes a rise in pressure. 2.4 holding time, open system The time expected to elapse from initial filling level until the vessel is empty (no more liquid) calculated from heat leak data. 2.5
24、holding time, closed system The time elapsed from establishing the initial filling condition until the pressure has risen, due to heat leak, to the set pressure of the pressure limiting device. NOTE : A pressure limiting device is either a safety valve or a rupture disc or a back pressure regulator
25、or any other device installed to limit the system pressure under normal operating conditions. 2.5.1 equilibrium holding time The holding time calculated from a specified heat leak assuming that liquid and vapour are constantly in equilibrium. STD-CEN EM 12213-ENGL 1998 m 34Oq587 0188737 121 = Page 7
26、 EN 12213:1998 2.5.2 optimum equilibrium holding time The equilibrium holding time calculated from heat leak data for a vessel when filled with the quantity of product giving the longest holding time. 2.5.3 static experimental holding time a) When the critical pressure is greater than set pressure o
27、f limiting device, the holding time of a closed system measured on a stationary vessel filled with a quantity of product which is calculated to fill the tank to its gross volume without hydrostatic deformation, with saturated liquid at the set pressure of the pressure limiting device. b) When the cr
28、itical pressure is less than set pressure of limiting device, the holding time of a closed system measured on a stationary vessel initially filled with the least mass of the specified product determined as follows : - the maximum allowable mass of filling ; or - the quantity of product which fills t
29、he vessel to its gross volume, without hydrostatic deformation, with liquid saturated to 99 % of its gross volume at the critical pressure. 3 General conditions for all methods The measurements described in this standard shall be carried out under the following conditions : 3.1 should normally be us
30、ed except in cases where the vessel to be tested is designed for a specific cryogenic fluid. The cryogenic fluid used for testing shall be chosen by the manufacturer. Liquid nitrogen 3.2 The liquid and gaseous phases shall be in equilibrium at the beginning of a test. When a test is carried out at a
31、 higher pressure than one bar gauge, it is important that the liquid equilibrium pressure is not lower than this test pressure. 3.3 The test environment shall be stable and constant during the test. It shall be as close as possible to the following reference conditions : - ambient temperature : 15 O
32、C ; - atmospheric pressure : 1 O1 3 mbar. For products except carbon dioxide and nitrous oxide : - vessel reference pressure : 1 O1 3 mbar. For carbon dioxide and nitrous oxide : - vessel reference pressure : 15 bar (gauge). 3.4 The vessel and its content shall have reached a stable temperature befo
33、re the beginning of the measuring period. Equilibrium conditions are obtained after a period of stabilisation, the duration of which depends on the size of the vessel and the type and configuration of the insulation. 3.5 shall be clearly defined and specified in the report. All accessories of the ve
34、ssel which can have an influence on the result of the measurement 3.6 All instrumentation used shall be periodically verified by calibration. 3.7 performance resulting from small modifications (this evaluation can be obtained by simple extrapolation). It is not necessary to use the method defined in
35、 this standard to evaluate the insulation 4 Measuring the heat leak by the loss of product method 4.1 General There are two methods of measuring the heat leak : - by direct measurement of loss of mass ; - by indirect measurement of loss of mass by measuring the gaseous volumetric discharge rate. The
36、 filling level shall be (50 * 10) % of the maximum filling level at the start of measurement, unless otherwise stated. The ambient temperature and the operating pressure at the top of the vessel shall be recorded throughout the test so as to be used for correction purposes. The temperature sensor(s)
37、 shall be placed in the immediate proximity of the test object, but sited such that they are unaffected directly by cold gas discharged from the vents. The minimum measurement duration shall be 24 h after stable conditions have been reached. During the test precautions shall be taken to avoid agitat
38、ion of the liquid. STD.CEN EN 12213-ENGL 1778 3404587 0188717 TT4 Page 9 EN 12213:1998 When measuring the rate of discharge of gas escaping from the vessel by a flow meter, it is essential that the entire gas flow passes through the meter. The gas flow rate shall be determined as a mass flow rate ei
39、ther by : - using a mass flow meter ; or - using a volumetric flow meter. An appropriate method is shown in annex A. 4.2 lest procedure The test procedure shall be as follows : step 1 step 2 : stabilisation ; : vessel precooling ; step 3 : adjustment of the filling to the intended starting level (e.
40、g. 50 YO * 10 Yo) ; step 4 : connection of instrumentation (e.9. gas flow meter) ; step 5 : second stabilisation period ; step 6 : determination of mass of contents of vessel at start of measuring period ; step 7 : a sufficient number of readings shall be taken to establish an acceptable thermal equ
41、ilibrium before the start of the measuring period ; step 8 : measuring period shall be at least 24 hours ; step 9 : determination of the loss of product in mass units (when gaseous flow is measured) in accordance with annex A ; step 1 O : reduction to reference conditions in accordance with annex B.
42、 4.3 Determination of the heat leak in units of energy per unit time The rate of product loss (kg/s) during the measurement period, corrected to the reference conditions in accordance with annexes A and B, shall be converted to an equivalent heat leak, Q, by multiplying it by the latent heat of evap
43、oration (J/kg) of the product at the reference conditions. To calculate the heat leak with a product other than the test product, compensation using linear extrapolation in accordance with annex C may be applied but only if the difference between the boiling temperature of these products at the refe
44、rence conditions does not exceed 20 OC. STD-CEN EN L2213-ENGL 1798 = 3LiOi587 0188720 7Lb Page 10 EN 12213:1998 4.4 Determination of the heat leak as a percentage of product lost per 24 h Based on the result obtained in accordance with 4.3, the heat leak as a percentage of product lost per 24 h is c
45、alculated as follows : a) correct the measured heat leak to reference condition for the test product by linear extrapolation as specified in 4.3 ; b) calculate the equivalent loss of the test product per day in accordance with the formula : where : F is the maximum allowable filling mass of the test
46、 product (kg) ; L is the equivalent loss of product in Yo of F per day ; Q is the heat leak (W) ; h is the latent heat of vaporisation (J/kg) at the vessel reference pressure (see 3.3) 86400 is the number of seconds per day. All product related data shall be taken at correct reference conditions for
47、 the specified product. Annex C may be used to determine the equivalent loss of product in % of full tank content per day, for product other than the test product. 5 Determination of the holding time (open system) in days from heat leak data for the specified product, which is equivalent to 100 The
48、holding time in days is equal to - L 1 O0 times the reciprocal of the loss of product per 24 h in percent (as determined in 4.4). 6 Holding times for closed systems 6.1 Determination of the equilibrium holding time from heat leak data The following general rules shall be applied : - the system is in
49、 thermal equilibrium, .e. the liquid and gas phases are saturated and at a temperature corresponding to the saturation pressure at all times. The calculation process shall incorporate correctly the temperature and pressure dependence of the thermodynamic properties. The data source used for calculations shall be identified and actual value be shown in the calculation. Thermodynamic data from reference l of clause 8 may be used. The influence of phase change in the system has to be accounted for in a proper manner ; - the thermal mass of the v
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