SIST EN 27841:2000

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Kondensatableiter - Bestimmung des Dampfverlustes - Prüfverfahren (ISO 7841:1988)Purgeurs automatiques de vapeur d'eau - Détermination de la perte de vapeur - Méthodes d'essai (ISO 7841:1988)Automatic steam traps - Determination of steam loss - Test methods (ISO 7841:1988)23.060.01Ventili na splošnoValves in generalICS:Ta slovenski standard je istoveten z:EN 27841:1991SIST EN 27841:2000en01-september-2000SIST EN 27841:2000SLOVENSKI
STANDARD



SIST EN 27841:2000



SIST EN 27841:2000



SIST EN 27841:2000



INTERNATIONAL STANDARD 7841 INTERNATIONAL ORGANIZATION FOR STANDARDIZATION ORGANISATION INTERNATIONALE DE NORMALISATION MEXAYHAPOJJHAR OPTAHM3A~Mfl fl0 CTAH~APTM3A~MM Automatic steam traps - Determination of steam loss - Test methods Purgeurs automatigues de vapeur d’eau - Dbermina tion de Ia perte de vapeur - M&hodes d’essai ISO First edition 1988-12-01 Reference number ISO 7841: 1988 (E) SIST EN 27841:2000



ISO7841 :1988 (EI Foreword ISO (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 ISO technical committees. Esch 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, govern- mental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. Draft International Standards adopted by the technical committees are circulated to the member bodies for approval before their acceptance as International Standards by the ISO Council. They are approved in accordance with ISO procedures requiring at least 75 % approval by the member bodies voting. International Standard ISO 7841 was prepared by Technical Committee ISO/TC 153, Valves. Users should note that all International Standards undergo revision from time to time and that any reference made herein to any other International Standard implies its Jatest edition, unless otherwise stated. l 0 International Organkation for Standardkation, 1988 Printed in Switzerland SIST EN 27841:2000



INTERNATIONAL STANDARD ISO 7841 : 1988 (EI Automatic steam traps - Determination of steam loss - Test methods 1 Scope and field of application This International Standard specifies two test methods to determine the steam loss of automatic steam traps to ISO 6552. The Object of these tests is to determine the amount of live steam, if any, that is lost through the steam trap. They are, therefore, tests to evaluate the ability of the traps to shut against steam during successive operations. There is no measurement of the total heat energy lost by the trap. Such total heat loss would include radiation and convec- tion components which tan be established separately. 3 Test arrangements The Pest arrangements for steam loss determination are shown in figures 1 and 2. The minimum water capacity of the calorimeter tank (sec figure 1) shall be 0,02 m3. lt is most im- portant that the condensate drainage device be fully capable of maintaining a dry line to the heat exchanger. The test device shall be located sufficiently below the heat exchanger to pre- vent condensate backing up into the heat exchanger, should the test device only operate infrequently. All piping and equipment (including the heat exchanger) shall be insulated to a value of R > 0,75 x 10-3 rn2. OC 9 h J 2 References ISO 651, Solid-stem calorimeter thermometers. ISO 652, Enclosed-scale calorimeter thermometers. ISO 653, Long solid-stem thermometers for precision use. ISO 4185, Measurement of liquid flow in closed conduits - Weighing me thod. ISO 6552, Automatic steam traps - Definition of technical terms. to reduce thermal losses to a minimum. The instruments used for the measurements shall comply with International Standards, if such Standards exist, e.g. - ISO 651, ISO 652, ISO 653 for temperature measurements; - ISO 4185 for flow measurements. The condensate removal device shall not be modified in any way from its commercial form. 1 SIST EN 27841:2000



Valve 5 Cooling watet- in Valve 1 Steam in D 8 S . . . I u l ap n . . Valve 2 T Condensate drain device Heat exchanger Valve 4 1 Vacuum breaker 1) Cooling water out To drain Valve 6 Vented cover or plastic ball: L To drain Valve 7 To drain i e 1 ---rn- I e 2- mf Calorimeter tank *$z!d-J Exchanger water tank m 3 m4 Figure 1 - Test arrangement for steam. loss tests with test method A 1) Operating at steam temperature. SIST EN 27841:2000



The test may be carried out at a pressure corresponding to the maximum working pressure of the trap, the test pressure not exceeding 32 bar’) with saturated steam (238 OC). Load testing shall be carried out at 1 % of the maximum capacity of the trap at the corresponding test pressure with a minimum of 5 kg/h. 4.1 Procedure 4.1 .l No-load condition Start with all valves closed and tanks empty. 4.1.1.1 Open valves 1, 2 and 3 to permit the drain and test devices to operate at test pressure ps. 4.1.1.2 During warm-up, weigh and record the mass of the empty calorimeter tank m,, and record the steam pressure ps and steam temperature 8,. 4.1.1.3 Fill the calorimeter tank with sufficient water (about half-full) to result in a test run of practical duration. The initial water temperature 8, should be at least 8 OC below ambient temperature 0,. Record the water temperature 8, and mass of water plus tank ml. 4.1 .1.4 When thermal equilibrium is reached, simultaneously and rapidly close valve 3, open valve 4, and Start the timing in- terval. The use of a three-way valve is recommended to facilitate rapid closing and opening. 4.1.1.5 Stir the water in the tank as necessary to ensure a uniform water temperature. 4.1.1.6 When the temperature of the water in the tank is as many degrees above ambient as the initial temperature was below, rapidly close valve 4 and open valve 3 simultaneously, record the elapsed time, the final water temperature e2 and the mass of water plus tank m2. 4.1.1.7 Before the measurement, trial runs should be carried out to ensure that the test conditions have stabilized and that the pressure, temperature, initial amount of water in the calorimeter tank and load conditions are those required. When testing condensate removal devices, an error calculation is made from three consecutive tests to determine the accuracy of the test result. The error calculation is based on the instrumentation used and described in this International Standard; or the average result from three consecutive tests shall agree within 10 % or 500 g/h, whichever is the greater. If this cannot be obtained, check the System for integrity and increase the calorimeter tank capacity. 4.1.2 Load condition Start with all valves closed and both tanks empty. 4.1.2.1 Open valves 1, 2 and 3 to permit the drain and test devices to operate at test pressure ps. 1) 1 bar = 105Pa 4.1.2.2 During warm-up, weigh and record the mass of the empty calorimeter tank m,, and record the steam pressure ps and steam temperature 8,. 4.1.2.3 Open valves 5 and 6 to allow a flow of cooling water through the heat exchanger, to create the desired condensate load on the test device. After the System has come to equilibrium, this load tan be determined by closing valve 6 and opening valve 7, to permit a known amount of water to be col- lected in a given time. Record the temperature of water entering and leaving the heat exchanger, & and eL, the initial and final mass of exchanger water plus tank, m3 and m4, and the time At, in seconds, of run on the Data Sheet in 4.3. The approximate condensate load, in kilograms per hour, on the trap may then be calculated using the formula (8 Load = L -eE) (m4 -m$ x 3600 At . hfgs where hfgs is the specif ic enthalpy of the inlet conditions, in joules per kilogram. evaporation at steam 4.1.2.4 If the load on the trap as determined in 4.1.2.3 is as desired, proceed to 4.1.2.5. If it is not as desired, adjust valve 5 accordingly and repeat the procedure in 4.1.2.3 until the desired load is obtained. 4.1.2.5 Fill the calorimeter tank with sufficient water (about half-full) to result in a test run of practical duration. The initial water temperature 8, should be at least 8 OC below ambient temperature 8,. Record the water temperature 8, and mass of water plus tank ml. 4.1.2.6 When thermal equilibrium is reached, simultaneously and rapidly close valve 3, and open valve 4, and Start the timing interval. The use of a three-way valve is recommended to facilitate rapid closing and opening. 4.1.2.7 Stir the water in the calorimeter ensu re a uniform water temperature. tank as necessary to 4.1.2.8 When the temperature of the water in the calorimeter tank is as many degrees above ambient as the initial temperature was below, rapidly close valve 4 and open valve 3 simultaneously, record the elapsed time, the final water temperature 02 and the mass of water plus tank m2. 4.1.2.9 Before the measurement, trial runs should be carried out to ensure that the test conditions have stabilized and that the pressure, temperature, initial amount of water in the calorimeter tank and load conditions are those required. When testing condensate removal devices, an error calculation is made from three consecutive tests to determine the accuracy of the test result. The error calculation is based on the instrumentation used and described in this International Standard; or the average result from three consecutive tests shall agree within 10 % or 500 g/h, whichever is the greater. 3 SIST EN 27841:2000



ISO 7841 : 1988 (El mf is the final mass of cal orimeter, in kilograms; water condensate in the If this cannot be obtained, check the System for integrity and increase the calorimeter tank capacity. ml is the kilog ra ms; mass of calorimeter plus water, at the Start, in 4.2 Expression of results 4.2.1 Correction of measured variables m2 is the kilog ra ms; calorimeter plus water, at the finish, in The values of observed variables shall be corrected in accord- ante with instrument calibrations and, if necessary, converted to the proper units required for calculations. mt is the mass of calorimeter tank, in kilograms; hfl is the calorimeter, initial specific enthalpy n joules per kilogram; of i 4.2.2 Use of formula Symbols hf2 is the final specific enthalpy of the condensate water i n the calorimeter, in joules per kilogram; The Symbols used in this International Standard are the ones normally associated with engineering practice in this field. In a few cases, the same Symbol has different meanings in different Parts of this International Standard according to its application. In Order to avoid confusion, each formula has been provided with its own list of definitions of Symbols and units. hf, is ditions, the liquid at steam inlet con- the specific enthalpy of in joules per kilogram; hfgs is the specific enthalpy of the evaporation at let conditions, in joules per kilogram; steam in- 4.2.3 Computation formula cP is the specific heat of the cal per kil ogram kelvin; orimeter ma teria 1, in qrns = -h, (mf-m$+c,m, (0241) 3600 1 X- hfgs At 81 is the initial water in degrees Celsius; temperature in the calori tank, O2 is the water degrees Celsius; temperature in the calorimeter tank, in 4 ms is the steam loss, in kilograms per hour; mi is the kilograms; initial mass of in the calorimeter, in At is the time interval, in seconds. 4 SIST EN 27841:2000



ISO 7841 : 1988 (EI 4.3 Data sheet Test Method A General information 1 Test No. . 2 Testdate : . 3 Location : . 4 Manufacturer’s name : . 5 Serial No. : . 6 Typeofdevice: . 7 Size: . 8 Calorimetermaterial : . 9 Massofemptycalorimeter,m,= . Averaged and corrected test data 10 11 12 13 14 15 16 17 18 19 Mass of calorimeter plus water, Start, ml = . kg Mass of calorimeter plus water, finish, m2 = . kg Mass added to calorimeter, Am = . kg ltem 11 - ltem 10 Timeinterval,At= . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . s Ambient temperature, 8, = . OC Steam temperature at trap inlet, 8, = . OC Initial water temperature in calorimeter tank, 8, = . OC Final temperature of water and condensate in calorimeter tank, 82 = . OC Barometricpressure,p, = . bar Steam pressure at trap inlet, ps = . bar Thermodynamic properties 20 Referenceusedforspecificheatdata:. 21 Reference used for steam/water data : . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Specific heat of calorimeter material, cp = .
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