Water vapour permeability test through leather with
Contents
1. As they are cut place them in test room in which the permeability test will be performed It is recommended that sample temperature is close to ambient temperature of test room Test procedure consists of two activities Sequence of their performance does not influence the result of test procedure The first step is determination of distilled water decrement which permeates through a sample as result of pressure created inside the Sampler 2000 The second part of test procedure is determination of water vapour decrement with no sample put into the Sampler It is a so called zero test 5 000 4 975 4 950 4 925 4 800 3 875 4 850 4 825 4 800 0 500 1000 1500 2000 2500 3000 3500 4000 TIME s i Permeability is expressedin MM S Am Ps AtS Where Am mass decrement At measuring time S sample surface 3 3 1 Procedure course part one 1 Start a moisture analyzer according to procedures described in user manual of the instrument 2 Take out the standard cross holding the weighing pan and install cross from Sampler 2000 kit Cross mass is adjusted in such a way that it equals mass of standard cross 3 Start computer and software PomiarWin if this means of data record is required 4 place a leather sample inside the sampler cover the top side of a sample should face upwards towards the holes in sampler cover Comments In case of samples with low thickness use optional pressu2. In order to evaluate ambient conditions and their influence on leather samples an operator has to be familiar with leather structure and changes that may occur as result of temperature and humidity change It is quite important aspect as it has been assumed that samples are not acclimatized before test procedure 5 Reference methods 5 1 Water vapour permeability matching with method PN 74 P 22138 This measuring process is to determine the amount of water vapour that permeates through sample surface from air conditioned room to dry silica gel in set amount of time A 60 mm in diameter sample is cut from a selected piece of leather and acclimatized in temperature ranging from 20 30 C and relative humidity of 65 5 for the period of minimum 24 hours Measuring vessel is filled with dried silica gel Than rubber and leather sample are put onto the vessel Finally the vessel is closed with a leakproof turn button Leather sample that is used for Ea ee top surface of shoes should face its use side to silica gel The vessel is placed in an exsiccator with water and in room with temperature 20 2 C After 24 hours the vessel with sample should be taken out from the exsiccator weighed and again placed in the exsiccator for another 48 hours After this time the vessel with sample should be weighed again Water vapour permeability that is matched by this method is expressed in milligrams of permeated vapour at 1000 mm of leather
3. Start computer and software PomiarWin if data record is necessary 3 Install a sampler according to below presented schema l sampler body 2 pressure ring 3 upper pan of a sampler 5 sampler cover A Schema of sampler mounting kit for zero test _Q 4 Locate the mounted sampler inside drying chamber of a moisture analyzer and as it stabilizes press ZERO TARE button 5 Program drying parameters for temperature 40 C test time 60 minutes time defined switch off displayed result g a moisture analyzer sends current weighing data through RS 232 according to set time interval Communication time interval is set in menu P5 03 Line_t print time interval 6 Start drying process at moment of placing a sample using a pipette dose approximately 3 g Mol of distilled water to sampler interior If a moisture analyzer does not cooperate with any peripheral devices note down mass of dosed water 7 Start drying process During drying process the display of a moisture analyzer will indicate data like current quantity of distilled water test time temperature in drying chamber 8 On analysis completion the display of moisture analyzer will indicate final water mass that is in the sampler M02 Assuming that test conditions are compatible with the recommendations from point 3 1 and that temperature of distilled water is stabilized with ambient temperature of test r
4. AMDE CONCIUONS aspasia E R E E E E seus aansedvanenctuascenndies 12 Dx FREE OEE MCE MENO Serra Sth tata E E E R 12 5 1 Water vapour permeability matching with method PN 74 P 22138 oo eee 12 5 2 Water vapour permeability matching with method PN 71 P 22150 aaae 13 5 3 Water vapour permeability matching with method PN EN ISO 14268 000000 14 5 4 Comparison tests for various kinds of leather cccccssssesececeeeeeeeeeseeeeeeeeeeeeaas 14 1 Introduction A set for testing water vapour permeability consists of two components The first one is a sampler 2000 the other one is a moisture analyzer The sampler is dedicated directly to moisture analyzers and its application for other tests is not possible A moisture analyzer is a standard instrument and it can only be utilized as A precision balance with specific readout precision An instrument for determination of moisture content dry mass content in vvarious samples As the Sampler 2000 is installed in the moisture analyzer it 1s possible to perform control process in which permeability of water vapour through various kinds of leather is tested The procedure is clearly described in the latter part of the publication A design including a moisture analyzer and sampler is a new developed technology for testing water vapour permeability the method presented below does not require leather seasoning Thus it causes significant shortening testing procedure if compare
5. C Humidity change during test procedure should not exceed 5 It is assumed that drying chamber temperature in which the sampler is located is stable during test procedure 3 2 Devices and substances used for method processing A workstation for water permeability test should be equipped with below specified devices and substances A moisture analyzer with readability 1mg Sampler 2000 Thermohigrobarometer record of ambient conditions A pipette transport of distilled water Distilled water Control thermometer PT 101 control of distilled water temperature and control of temperature inside drying chamber of a moisture analyzer optional equipment A computer with PomiarWin software optional equipment 3 3 Determination process testing procedure Testing of water permeability should be performed in stable ambient conditions It is assumed that ambient conditions are stable if temperature and humidity are within specified thresholds and mentioned in point 3 1 above A moisture analyzer should be plugged to mains at least 30 minutes before test initiation Distilled water that is used for the test should have temperature close to ambient temperature of test room Water should be stored in test room for at least 24 hours before test procedure initiation for its thermal stabilization Sample collection and storage Cut a disc section of 54 mm 2mm from a selected piece of leather
6. Water vapour permeability test through leather with application of moisture analyzer series MAC 50 Manufactured by RADWAG The aim of this publication is to present an alternative method for testing water vapour permeability with application of moisture analyzers It is a new approach to this problem which has been developed by Chair of Technology and tanning Shoes at Technical University in Radom and participated by RADWAG Testing Laboratory New developed method shortens testing time which is significant for potential users RADWAG WAGI ELEKTRONICZNE TESTING LABORATORY TECHNICAL SUPPORT 26 600 RADOM 28 Bracka Street tel 48 0 48 38 48 800 ext 536 tel fax 48 0 48 385 00 10 http www radwag pl CONTENT Ms MINEO GU CUO Mies grssstasatiseeseacetenetaegscantcta atoms uhenes EE 3 2 Sampler 2000 GESIEN meria tiicdinie tieiaaiadial a oie Seaalielnitielsaiadiel stent tails 3 3 Description of a method for water vapour permeability with application of moisture analy zo Sonce taseialeadadahtensealeteiae eins lesduaateann EE N 4 FETO On a er men nen em On rs E ere 5 3 2 Devices and substances used for method processing seesssssssssserrssssssssserressss 5 3 3 Determination process testing procedure ssseseeessssssssecerrsssssssscereresssssseeerrsssss 5 A SOU S Or OTOES a O S 12 Alc Morst rc anal yZ sins andaicuuncwanevateatputad E OEA 12 a 2 A I E EE S E TEE E E alee A A E E E 12 A 3
7. d to method no PN P 22138 As comparison tests there have a series of tests performed for water vapour permeability through different kinds of leather The tests were conducted in RADWAG Testing Laboratory and Chair of Technology and tanning Shoes at Technical University in Radom 2 Sampler 2000 design A sampler is an aluminum device that consists of a body cover sealing ring and another cover If all components are connected than the sampler is a leakproof construction in which distilled water is evapourated Measuring method and sampler design are legally protected by patents sampler W 116646 measuring method P 381787 l Body of a sampler holds distilled water during testing procedure 2 Expansion ring causes sample seizure when it is fitted to the sampler with large allowance 3 Upper sampler pan it is used only during so called zero test 4 Sealing ring it is used as a pressing element for samples with low thickness 5 Sampler cover closure of sampler construction 3 Description of a method for water vapour permeability with application of moisture analyzers Water vapour permeability is precise measurement of mass decrement of water which evapourates from sampler interior through tested leather sample Water vapour permeates through leather as result of its pressure increase which is caused by increasing temperature inside the sampler A testing device for permeability method is a moisture anal
8. efore test procedure in mg Moz vessel mass with sample after test procedure in mg t procedure time in hours h P surface of a sample 20 cm 14 Permeability result PN EN ISO Sampel name Sampler 2000 14268 2005 PN P 22138 IPS Tanning Lab ee Cowhide footwear black Cowhide footwear Eor 17 760 Cowhide footwear Cowhide footwear pressed 10 929 oad Split cowhide lining O 547810 O 547810 OOOO RB ko Comparison of results e PS Lodz a Probe 2000 3 4 Sample number Comparison tests performed by IPS have indicated compatibility of results if it is assumed that test results obtained by method Sampler 2000 are expressed in mg em h _15
9. gt cE al Ie sl ae ole de Is ode en al ele Sn ed lee ke ah Eel ay wd kee dr ok och eh ah ak cis aka tak We ale ak lt a Vir ths ae 1 4 7 10 13 16 19 22 25 28 31 34 37 40 43 46 49 52 55 58 Time min Bottom surface of a sample oe 4 Sources of errors If a result of water permeability performed according to above described method is inaccurate or burdened with dispersion than it may result from several 4 1 Moisture analyzer The main factor referring to moisture analyzer is actual temperature in drying chamber of the instrument It should be maintained on constant level during an analysis As the test temperature is set for 40 C it is not possible to overheat a sample as result of too high temperature Any indication changes resulting from drifts of air in drying chamber are minimal and can be neglected 4 2 Sampler In case of a sampler it is possible that a sample is incorrectly positioned sample seizure failed If such problem occurs than decrement of distilled water will be much higher than in case of correct sample seizure In case of leather samples with low thickness apply pressure ring which is part of sampler kit 4 3 Ambient conditions Influence of ambient conditions should be considered from the point of moisture analyzer and tested sample it can be assumed that if ambient conditions are stable than evapouration of distilled water is equal in case of zero test and leather sample test
10. in 24 hours The result is calculated from below formula m m 1000 2 y where X water vapour permeability mg 1000mm 24h m mass of weighing vessel with sample after 24 hours mz mass of weighing vessel with sample after 72 hours 5 5 2 Water vapour permeability matching with method PN 71 P 22150 This method is to determine mass of water vapour which permeates from area with higher vapour pressure to area with lower vapour pressure in specified amount of time Each tested sample should be placed on opened neck of a clean and dry vessel designed for this method which is half filled with silica gel Each sample should be weighed with a vessel and then located it in a specially designed six star holder Then place the vessels and the holder in air conditioned room Place a vent over the holder start holder with vessels and acclimatize them for 24 hours As time elapses dismount vessels from holder and weigh them Water vapour permeability that permeates through 1 cm of sample surface in 1 hour is calculated in milligrams from a formula x gt Ime lom Ihy Z where X water vapour permeability mg 1000mm 24h g increase of vessel mass with sample mg t total time of test procedure h 1 r tested sample surface cm 13 5 3 Water vapour permeability matching with method PN EN ISO 14268 According to this method a sample is seized and affected by strong wind blo
11. oom than result of zero test can be accepted as constant Decrement of water during test depends on Quantity of heat which is directed to the sample temperature in drying chamber of a moisture analyzer Initial temperature of distilled water too low temperature will require consumption of some energy for balancing thermal balance 10 3 3 3 Calculation of water vapour permeability Calculation of water vapour permeability should be performed according to below specified formula MI M2 _ 100 Mol Mo2 where P water vapour permeability expressed in M1 initial mass of distilled water during leather sample testing M2 final mass of distilled water during leather sample testing Mol initial mass of distilled water in zero test Mo2 final mass of distilled water in zero test Relation Mol Mg2 can be assumed as constant In such case there is no need to repeat zero tests as they are considered constant Application of a computer provides a possibility to draw a graph from drying process and do observation from performed analysis Below there is an instance of a graph which presents decrement of distilled water while testing furniture cowhide 2 3 mm thick Sample nr 2 3 5 001 4 991 D 4 981 Top surface of a sample 4 971 4 961 4 951
12. re ring This way the sample is properly seized A sample should have adequate dimensions If it is too small it will not maintain leakproofness If it is too big than it will prevent proper contact between body and cover of the sampler 5 Place below components inside drying chamber of a moisture analyzer Sampler cover with leather sample Pressure ring Sampler body As the display indication stabilizes press ZERO TARE button all elements put on weighing pan of the instrument are tarred 6 Program drying parameters for temperature 40 C test time 60 minutes time defined switch off displayed result g a moisture analyzer sends current weighing data through RS 232 according to set time interval Communication time interval is set in menu P5 03 Line_t print time ae Comments As drying chamber cover is closed drying process starts automatically It finishes automatically after 60 minutes of set time During test procedure a moisture analyzer will send data on distilled water mass If no graph from test interval Start drying process During drying process the display of a moisture analyzer will indicate data like current quantity of distilled water test time temperature in drying chamber etc At the moment of placing a sample using a pipette dose distilled wate r approximately 5 g M1 of distilled water to sampler inte
13. rior If a moisture analyzer does not cooperate with any peripheral devices note down mass of dosed water Take the sampler out of drying chamber and close tight the sampler cover to its body The sample should be seized Pay attention not to pour distilled water from the sampler 10 As closed place the sampler inside drying chamber of a moisture analyzer process is created than relevant data are initial and final mass of distilled water 11 On analysis completion the display of moisture analyzer will indicate final mass M2 that is in the sampler on pd I body of a sampler 4 2 pressure ring 3 3 leather sample 4 sealing ring 2 optional its application depends on sample thickness i 5 sampler cover A schema of sampler for test with leather sample Caution Time interval for data sent by a moisture analyzer are set in parameter P5 Print data transmission RS 232 P5 03 LinE_t print time interval gt 1 2 3 5 10 20 30 60 120 1 80 3 3 2 Procedure course part two zero test Zero test is determination of evapouration speed of distilled water from a sampler that is located in drying chamber of a moisture analyzer with temperature set for 40 C and test time 60 minutes The test does not require seizure of a leather sample in sampler interior The test procedure is described below 1 Start a moisture analyzer according to procedures described in user manual of the instrument 2
14. w in standard atmosphere i e 20 C 65 or 23 C 50 Air that is inside a container is continuously mixed by a dry agent which is put into motion by rotating container Before and after test procedure the container is weighed and mass of absorbed humidity is calculated from the difference in mass of dry agent Water vapour permeability is calculated by milligrams square centimeters and hours by below presented formula Pwv d P mg 1cm7 1h where M increment of container mass M Mo in milligrams d average length of container s neck diameter in millimeters t time between first and second weighing in minutes 5 4 Comparison tests for various kinds of leather Each new testing method requires a qualification process which orders comparison of test procedures performed for the same types of samples In case of Sampler 2000 method a comparison is relatively difficult as traditional method specifies results in mg cm h and Sampler 2000 method gives percentage result Nevertheless such comparison tests have been performed by Institute of Leather Industry in Lodz Tanning Laboratory The test has been performed according to norm no PN EN ISO 14268 2005 Additionally water vapour permeability has been calculated for method Sampler 2000 The applied formula came from norm no PN P 22138 p mg t P cm h p where P water vapour permeability in mg cm h M vessel mass with sample b
15. yzer It is designed from a precision balance with readability of 1 mg and a drying chamber with set of halogen lamps temperature sensor and converting circuits with a digital display Precision balance is to precisely determine mass in testing cycle Electronic circuit through feedback from temperature sensor and halogen lamps maintains set temperature Electronic components of a moisture analyzer process collected data and indicate results on moisture analyzer display Data recording takes place automatically with no operator action with set time interval Data can be processed on Personal computer with installed and active software PomiarWin Printer Manually by making notes The most convenient and recommended solution is a computer with installed software Collected data are used for designing a graph from drying process The graph indicates speed of water vapour permeation though testes leather sample and speed of water evapouration in zero method The measure of water vapour permeability is quantity of water vapour expressed in that permeates through a substance leather compared with decrement of water mass that evapourated from a sampler in zero test 3 1 Test conditions As for test conditions the operator should monitor ambient temperature and humidity Ambient temperature should be set between 21 C to 26 C and humidity between 40 to 60 Temperature changes during test procedure should not exceed 2
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