Water Vapor Transmission Rate (WVTR) ASTM F Permeation of Flexible Barrier Materials Using a Modulated Infrared Sensor. Water Vapor Transmission . Designation: F – 05 Standard Test Method for Water Vapor Transmission Rate Through Plastic Film and Sheeting Using a Modulated. ASTM F outlines an instrumented procedure for determining the rate of water ASTM F is a standard test method for measuring the water vapor.
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ASTM F — ASTM D water c A number in parentheses indicates the year of asfm reapproval. A superscript epsilon e indicates an editorial change since the last revision or reapproval. The method is applicable to sheets and? It provides for the determination of 1 water vapor transmission rate WVTR2 the permeance of the?
NOTE 1—Values for water vapor permeance and water vapor permeability must be used with caution.
The inverse relationship of WVTR to thickness and the direct relationship of WVTR to the partial pressure differential of water vapor may not always apply. The permeability is meaningful only for homogeneous materials, in which case it is a property characteristic of bulk material. The test conditions see 3.
Since the permeance of a specimen is generally a function of relative humidity and temperature, the test conditions must be stated. The test conditions of relative humidity and temperature where the humidity is the difference in relative humidity across the specimens, must be stated. Summary of Test Method 4.
Water Vapor Transmission Rate (WVTR) ASTM F1249
The asmt chamber and the wet chamber make up a 1. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
Current edition approved Oct. Originally approved in Last previous edition approved in as F — Water vapor diffusing through the? This sensor measures the fraction of infrared energy absorbed by the water vapor and produces an electrical signal, the amplitude of which is proportional to water vapor concentration.
The amplitude of the electrical signal produced by the test? Xstm information is then used to calculate the rate at which moisture is transmitted through the material being tested. A typical acceptable diffusion cell area is 50 cm2. The volume enclosed by each cell half, when clamped, is not critical; it should be small enough to allow for rapid gas zstm, but not so small that an unsupported? A depth of approximately 6 mm 0.
The test area is considered to be the area established by the inside contact diameter of the compressed O—ring when the diffusion cell is clamped shut against the test specimen. This is a critical sealing f1294 against which the test specimen is pressed; it shall be smooth and without radial scratches. This is necessary only in the earlier model WVTR instruments that have a separate conditioning rack and testing chamber. These shall incorporate O—rings suitable for sealing the diffusion cell to the test chamber pneumatic?
NOTE 2—Use of Multiple Diffusion Cells—Experience has shown that arrangements using multiple diffusion cells are a practical way to increase the number of measurements that can be obtained in a given time. A separate conditioning rack Fig. Dry air is continually purging the dry chamber of those cells that are connected to the conditioning rack while the humid chamber side is held at a speci?
It is desirable to thermostatically control the temperature of the conditioning rack as described in 6. Your comments will receive careful consideration at a meeting of the responsible technical committee,1 which you may attend. Again, this is necessary only in the earlier model WVTR instruments that have a separate conditioning rack and testing chamber.
The test chamber shall incorporate means for clamping the diffusion cell in accurate registration with pneumatic system openings to the dry-air source and the infrared detector. The chamber shall also provide a thermometer well for the measurement of temperature.
ASTM F – pdf – ASTM F Standard Test Method for Water Vapor Transmission_百度文库
A thermistor sensor and an appropriate control circuit will serve to regulate the temperature unless measurements are being made close to ambient temperature.
In that case it may be necessary to provide cooling coils to remove some of the heat. In earlier model WVTR equipment, a separate desiccant drying system is needed for the conditioning rack and test chamber. Reagents and Materials 7. Necessary only in earlier model WVTR equipment that utilizes distilled water or saturated salt solutions to generate the desired relative humidity. Newer WVTR equipment does not require saturated salt solutions.
Needed only with certain WVTR instruments. Sampling may be done in accordance with Practice D Select samples considered representative of the material to be tested. If the material is of nonsymmetrical construction, the orientation should be noted. System Calibration With Astn Film 9.
If unfamiliar with the material being tested, the operator should investigate the effect of conditioning time to be certain that sufficient time has been allowed for the material to equilibrate under the test conditions see Note 3. NOTE 3—When testing materials for which the operator has no previous history, additional time must be allowed to assure that true equilibrium has been ast.
When in doubt, retest after an additional conditioning interval of several hours. Temperature is a critical parameter affecting the measurement of WVTR.
During testing, monitor the temperature, periodically, to the nearest 0. Report the average temperature and the range of temperatures observed during the test. If the material is nonsymmetrical two sides differentinclude a statement as to which side was facing the high humidity, These entries should be rounded off to three signi? Precision and Bias The number of laboratories and ast in this study does not meet the minimum requirements for determining precision prescribed in Practice E Of the total eight laboratories that participated in this round robin, one did not report results for the PET sample.
Water Vapor Transmission Rate (WVTR) ASTM F
astk Due to equipment limitations, only? Precision, characterized by repeatability Sr and r, and reproducibility SR and R, has been determined for the following materials to be: The value of C is derived from tests of a known reference?
Newer computer-controlled systems will automatically calculate the WVTR. Permeability calculations are meaningful only in cases where materials have been determined to be homogeneous. The accuracy of this method is therefore dependent upon the validity of the values assigned to these reference? This information should be available from the manufacturer of the reference? Above that level, a different approach may be required in order to keep the sensor output within design limits.
This may be accomplished in two ways: These may be applied to both sides of a barrier to reduce the sample area. Metal masks utilizing a neoprene O-ring are yet another alternative.
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