Wet Cup Research Articles

Hygrothermal Characterization of Porous Building Materials-New Research Method on Water Vapor Transmission

The research on water vapor transmission (WVT) has an important function on analyzing moisture transport through building materials. According to ASTM Standards, there are two traditional methods (Dry cup and Wet cup) to test WVT of porous materials for practical application, without considering the influence of relative humidity and air flow. In this paper, multilayer method is used to test WVT of porous materials, without the influence of air flow on the whole testing process. Multilayer test method is the new way and there is little experience on how to conduct the whole process, how to obtain the accurate data and make the whole process reasonable is the big issue. Through several cases are worked on and analyzed, then renew desiccant every two hour which is depending on the type of porous materials, is the best way to make the whole testing system reaching to steady state for special building materials. At last, this paper shows that the new way is more reasonable and has higher accuracy than traditional method to get WVT.

Grey Relational Analysis on the Factors of the Moisture Permeability of Cotton Fabrics

Moisture permeability is an important property of cotton fabrics. Fully understanding of cotton fabric moisture absorption and moisture permeability plays an important role in the further study of the cotton fabric property and development of new cotton fabric. According to 6 kinds of cotton fabrics, the moisture permeability was measured by wet cup moisture absorption method under normal temperature. Such structural parameters have been analyzed as the yarn density, warp and weft density, weight per square meters, thickness, twist, which influenced the moisture permeability of fabrics. By the grey relational analysis, the grey relational sequence of structural parameters have been concluded which affect the moisture permeability of fabrics: thickness>weight per square meters>weft density>weft twist>warp density>wefts yarn density>warp twist>warp yarn density. The results provide theoretical basis for research and designing of textile products and modification of fabrics.

The feasibility of acquiring a thermal analysis cooling curve by wet sample cup made of green sand

The purpose of this study is to determine whether it is feasible to acquire the cooling curve with obvious characteristic points by the wet sample cups made of green sand. If it were feasible, this would replace the traditional dry sample cup and thus reduce the expenditure. Taking full consideration of the thermocouple position, and the volume and thickness of the sample cups, a set of molds is designed to make the wet sample cups with different dimensions. Also, a measuring system is constructed to automatically acquire and record the cooling curve during solidification. Using these wet sample cups with several different thicknesses and volumes, many experiments on the eutectic Al-Si alloys and LY12 aluminum alloys have been performed and the recorded cooling curves have been analyzed, respectively.

Moisture barrier properties of xylan composite films

Moisture barrier properties of films based on xylan reinforced with several cellulosic resources including nanocrystalline cellulose, acacia bleached kraft pulp fibers and softwood kraft fibers have been evaluated. Measurements of water vapor transmission rate (WVTR) were performed by a modification of the wet cup method described by ASTM E 96-95, indicating that membranes with 10% nanocrystalline cellulose, prepared using a sulfuric acid, exhibited the lowest permeability value of 174gmil/hm2 among the composite films studied. Both the acacia and the softwood kraft pulp fibers when used for xylan film formation exhibited higher water vapor transmission rates at addition levels of 50% and no improvement at lower levels of 5% and 10%, in comparison to control xylan films. Reinforcement of xylan with hydrochloric acid made nanocrystalline cellulose yielded films that showed a reduction in water transmission but the reduction was not as significant as with the reinforcement of xylan with sulfuric nanocrystalline cellulose. The results showed that xylan films reinforced with 10% sulfuric nanocrystalline cellulose exhibited reductions in water transmission rates of 362%, 62% and 61% over films prepared with 10% softwood kraft fibers, 10% acacia fiber and 10% hydrochloric acid prepared nanocrystalline cellulose, respectively. The morphology of the resulting nanocomposite films was examined by SEM and AFM which showed that control films containing xylan and sorbitol had a more open structure as compared to xylan–sorbitol films containing sulfuric nanocrystalline cellulose. The results from FT-IR suggested strong interactions occurred between the nanocrystalline cellulose and the matrix.

Water Vapor Transmission Rate of Biomass Based Film Materials

Biomass based film materials have gained attention due to their carbon neutrality. Film materials which were designed for packaging of fresh produce require good water vapor transport control to extend the shelf life of the products. In this study the water vapor transmission rate was investigated and measured by a modified technique of wet cup method, according to ASTM E 96. Biomass based film materials presented higher value of water vapor transmission rate compared to the conventional polyethylene films. Loading of scallop-shell powder increased the ability of the film to absorb or immobilize water due to enhancement of the formation of pores when the film was stretched. In addition, the water vapor transmission rate increased with increasing temperature or relative humidity difference.

Thermal and moisture flux in soft fibreboards

The thermal conductivity of several wet and dry processed industrial soft fibreboards was determined at temperatures between 10°C and 30°C. Additionally, the thermal conductivity was tested relative to the moisture content ranging from an oven-dry sample to a moisture content of 85% relative humidity. Furthermore, the water vapour diffusion was investigated to determine the resistance factor and the diffusion coefficient under ‘dry cup’ and ‘wet cup’ conditions and the sorptions were tested by means of the sorption isotherms. The thermal conductivity increases with increasing temperature at about 0.45% per Kelvin and with increasing moisture at about 0.17×10−2 W/mK per percent volumetric moisture content. Furthermore, the thermal conductivity depends on the manufacture (dry or wet process) and is influenced by density. The water vapour resistance factor increases and the diffusion coefficient decreases with increasing density. Both factors decrease with increasing moisture content and they are dependant on board thickness, composition and manufacturing. The sorption isotherm is similar to solid wood below about 80% relative humidity but strongly increases for soft fibreboards with binding fibres and additives of ammonium phosphate or sodium borate and boric acid when above 80% relative humidity.

Vapor Permeability Measurements: Impact of Cup Sealing, Edge Correction, Flow Direction, and Mean Relative Humidity

Abstract Water vapor permeability is a basic hygrothermal characteristic of a porous material. At first sight, the cup test used for measuring the property looks simple. Conditions to be fulfilled, however, are that the vapor flow crosses the sample only, is one-dimensional, and that flow direction has no impact on the result. Flow through the sample only demands a perfectly vapor-tight edge-high seal between sample and cup. That condition was tested using different sealing solutions. The results learned that more precautions than expected were needed. If the flow is not one-dimensional, for example, because such perfect seal is only realizable for a sample larger than the cup mouth, an edge correction must be applied to the value measured. As far as direction is concerned, measurements on a couple of hygroscopic materials gave different vapor permeability results for inward and outward flows. Long-lasting sorption after a fast initial hygroscopic moisture uptake appeared to be the reason for that. Dry, wet, and very wet cup testing shows that vapor permeability of hygroscopic materials increases with relative humidity. Some attribute that effect to surface flow from higher to lower relative humidity in the adsorbed water layers once beyond 50 % relative humidity. If that hypothesis was correct, apparent vapor permeability of hygroscopic layers, in situations where partial water vapor pressure and relative humidity gradients oppose, should be much lower than that measured with a wet cup. During the cold season opposing gradients are present in assemblies with a hygroscopic layer at the outside, covered by a vapor retarding finish. Yet, hot box testing on that kind of assemblies did not reveal vapor permeabilities lower than the wet cup value, although interstitial condensation between the hygroscopic and vapor retarding layer was a fact.

Length of Multiple-Funnel Traps Affects Catches of Some Bark and Wood Boring Beetles in a Slash Pine Stand in Northern Florida

The multiple-funnel trap has gained broad acceptance for catching bark and ambrosia beetles since the trap was developed more than 25 years ago (Coleoptera: Scolytidae) (Lindgren 1983). The trap consists of black plastic funnels aligned vertically over each other, allowing for intercepted beetles to fall through the funnels into a wet or dry collection cup located on the bottom funnel. Currently, there are 2 national programs in the USA that use baited multiple-funnel traps for detecting exotic species: the Cooperative Agricultural Pest Survey (CAPS) and the Early Detection and Rapid Response program (EDRR) (USDA APHIS 2007; Rabaglia et al. 2008). Multiple-funnel traps are available in several sizes or lengths, expressed by the number of funnels (4-, 8-, 12or 16-unit) (Contech Inc., Delta, BC; Synergy Semiochemicals Corp., Burnaby, BC). The general expectation is that longer multiple-funnel traps catch more beetles. In support of that position, Hoover et al. (2000) found that catches of the striped ambrosia beetle, Trypodendron lineatum (Olivier) (Coleoptera: Scolytidae), in traps baited with the pheromone lineatin, increased as the length of traps were increased from 4 to 16 units. Haack & Lawrence (1997) found that catches of Tomicus piniperda (L.) were higher in 12and 16unit traps than in 8-unit ones. The objective of our study was to verify that long multiple-funnel traps (16-unit) catch more bark and wood boring beetles than short traps (8unit) in a slash pine (Pinus elliottii Engelm.) stand in northern Florida. We focused our study on common southern species attracted to the binary combination of ethanol and (–)-α-pinene used in the national programs (Miller 2006; Miller & Rabaglia 2009). We conducted 1 trapping experiment in a mature slash pine stand on the Osceola National Forest near Olustee, FL for 9 weeks in 2001 (29 Aug-8 Nov). PheroTech Inc. (now Contech) supplied separate lures for releasing ethanol and (–)-α-pinene at rates of approximately 0.6 and 2 g/d, respectively, as well as 8unit and 16-unit multiple-funnel traps. Traps were set in 6 blocks of 2 traps per block with all traps set 10-15 m apart. There were 2 treatments: (1) 8-unit; and (2) 16-unit multiple-funnel traps. One trap of each treatment type was randomly assigned to a position within each block. All traps were baited with ethanol and (–)-α-pinene. Each trap was suspended between trees by rope such that the bottom of each was 0.2-0.5 m above ground level. No trap was within 2 m of any tree. Collection cups contained approximately 150 mL of pink propylene glycol solution (Peak RV and Marine Antifreeze, Old World Industries Inc., Northbrook, IL). Using SYSTAT ver. 11.00.01 (SYSTAT Inc., Point Richmond, CA), we conducted two-sided t tests on data transformed by ln(y + 1) to remove heteroscedasticity (Pepper et al. 1997). Catches of Arhopalus rusticus nubilus (LeConte) (Cerambycidae) in 16-unit traps were 143% greater than those in 8-unit traps (Table 1).

Examination of Stability of Boundary Conditions in Water Vapor Transmission Tests

The diffusion of water vapor through construction materials is driven by the gradient of partial water vapor pressure. Traditionally, water vapor transmission tests (WVT), the `dry cup', and the `wet cup' tests have been conducted with 0 to 50% RH, and from 50% to 100% RH, respectively. Often, desiccants, saturated salt solutions or distilled water are used to generate the required RH. The stability of vapor pressure in WVT tests is of paramount significance because these values are used in calculating permeance. Dry cup tests performed with high permeance materials (>25 Perms) indicated a transient behavior for the two types of adsorbing desiccants; calcium sulfate and silica gel. Monitoring RH inside the dry cup was performed to examine the effect of low and high WVT on the performance of moisture sinks. The results indicate that for highly permeable construction materials, the use of vapor pressures corresponding to 0% RH in calculation of permeance is not appropriate.

Water transmission barrier properties of biodegradable films based on cellulosic whiskers and xylan

The reinforcement of natural biopolymers with cellulosic whiskers has been shown to be beneficial for physical strength properties including xylan films. This study examines the water transmission properties of xylan films reinforced with cellulosic whiskers prepared from kraft pulp hydrolyzed with sulfuric acid. Measurements of water transmission rate (WVTR) were accomplished by a modification of wet cup method described by ASTM E 96-95. The results showed that films prepared by xylan reinforced by 10% sulfonated whiskers exhibited a 74% reduction in specific water transmission properties with respect to xylan film and a 362% improvement with respect to xylan films reinforced with 10% softwood kraft fibers.

Thermal conductivity and water vapour transmission properties of wood-based materials

For several wood-based materials (plywood, OSB, melamine faced board (MFB), particle board and fibre board), the thermal conductivity was determined as a function of the temperature (ranging between 10 and 30 °C) and also the moisture content (from an oven-dry sample up to a moisture content at 80% RH). Furthermore, the water vapour resistance factor of these materials as well as of the coating (at MFB) and the diffusion coefficient were determined under dry cup (performance at low humidity dominated by vapour diffusion) and wet cup (performance at high humidity with liquid water and vapour transport) conditions. Thermal conductivity increases with rising temperature, moisture content and density. Moreover, a clear decrease of thermal conductivity was found with decreasing particle size at the same density level, from solid wood over plywood and particle board to fibre board. The water vapour resistance factor of the wood-based materials increases with rising density and decreases with increasing moisture content. An influence of the particle and fibre board thickness was also revealed. In contrast to the remaining materials, an increase of the water vapour resistance factor with increasing moisture content was measured for the coating. The diffusion coefficient decreases with rising density and moisture content.

Comparison of Arboreal Beetle Catches in Wet and Dry Collection Cups with Lindgren Multiple Funnel Traps

We compared the effectiveness of a dry collection cup (with an insecticide killing strip) to a wet collection cup (containing antifreeze) for use with Lindgren multiple-funnel traps in catching several common species of bark and wood-boring beetles, and their associates in southern pine forests. All traps were baited with either the binary combination of ethanol and (-)-alpha-pinene or the quaternary combination of (+/-)-ipsenol, (+/-)-ipsdienol, ethanol, and (-)-alpha-pinene. We found that cup treatment had little, if any, effect on catches of Ips avulsus (Eichhoff) and I. grandicollis (Eichhoff) (Coleoptera: Scolytidae), Alaus myops (F.) (Elateridae), Chalcophora Solier species (Buprestidae), Temnochila virescens (F.) (Trogositidae), and Lasconotus Erichson species (Colydiidae). In contrast, catches of the following species were significantly less (by 40-97%) in traps with dry cups than in traps with wet cups: Hylobius pales Herbst and Pachylobius picivorus LeConte (Curculionidae); Buprestis lineata F. (Buprestidae); Acanthocinus obsoletus (Olivier), Arhopalus rusticus nubilus (LeConte), Monochamus titillator (F.) and Xylotrechus sagittatus sagittatus (Cerambycidae); Hylastes porculus Erichson and Xyleborinus saxeseni (Ratzeburg) (Scolytidae); and Thanasimus dubius (F.) (Cleridae). The same was true in at least one experiment for the following species: Dendroctonus terebrans (Olivier), Hylastes salebrosus Eichhoff, Hylastes tenuis Eichhoff, and Xylosandrus crassiusculus (Motschulsky) (Scolytidae). We conclude that cup treatment can have a significant impact on catches of some arboreal beetles in baited multiple-funnel traps. Anyone using multiple-funnel traps to capture arboreal beetles should evaluate the potential impacts arising from their choice of collection cup treatment to their trapping objectives and expectations. The issue of cup treatment may be particular important at low population levels when maximum trap efficiency is required such as in the detection of exotic insects at ports-of-entry and within quarantine and containment zones.

Measurement of Moisture Conductivity of Clothing

In this paper a method to measure the moisture (water vapor) conductivity of clothing is proposed. The method is based on the wet cup method, which is often used for building materials. The proposed method overcomes the difficulty of applying the wet cup method to thin and air-permeable material like cloth by determining the surface moisture transfer resistances at both sides of cloth gravimetrically. Measured results on cotton cloth are shown.

Measurement of water vapor transmission rate in highly permeable films

AbstractMeasurements of water vapor transmission rate (WVTR) are often based on the wet cup method described by ASTM E 96‐95. In attempting to compare the performance of thin polymer films with moderate to high water vapor permeability, it was observed experimentally that the ASTM method did not give reliable results for highly permeable films. In particular, the WVTR depended on film thickness and the ratio of film area to water surface area. It was determined that the high water vapor flux through the more permeable films caused a reduction in the driving force for water vapor transmission, that is, the relative humidity at the inner surface of the film. Consequently, the WVTR was underestimated. Comparisons based on a small area ratio and a constant small‐flux condition were considered as alternative approaches for evaluating performance using the wet cup method. The constant flux approach produced the best correlation with WVTR that was measured with a commercial instrument. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1624–1633, 2001

Effect of wind on drying from wet porous building materials surfaces—A simple model in steady state

The effect of wind on drying of wet porous building materials was studied. A model that assumes that evaporation from a material can be expressed by a surface resistance B was used. B gives the maximum drying capacity of a surface. B can be measured assuming that evaporation from the material is proportional to the evaporation from a free water surface, the material porosity and a material constant, K. Experiments were performed to verify the model and to provide material data on B using a wind tunnel. Steady state flow was measured through thin building material specimens mounted in “wet cup” specimen holders. Water was absorbed from the lower side and evaporated from the upper side of the specimens during exposure to wind. Six building materials with large variations in porosity and sorptivity were tested. K was quite constant for each material for wind velocities of 0.15–10 m/s, verifying the model. Wind affected flow more the higher the material sorptivity. Calculation of B at 50% relative humidity and wind velocities 0.15–10 m/s for the six materials is shown in the paper. B=Jh.K.e/(Hsurface-Henvironment) with Jh=evaporation rate from free water, e=material porosity and H=humidity. For concrete with w/c=0,75 at 10 m/s wind velocity, B=0.003 m/day.

An Alternative Procedure for the Analysis of Data from the Cup Method Measurements for Determination of Water Vapor Transmission Properties

Abstract The cup methods are used extensively to determine the water vapor transport characteristics of building materials. The dry cup method and the wet cup method prescribe two standardized procedures for this purpose. The dry cup method gives the results as an average value of the property at a mean relative humidity of 25% and the wet cup at 75%. This information is inadequate for detailed hygrothermal analysis of building components. The complete dependence of water vapor permeability on relative humidity is required by most of the current computer models used for hygrothermal analysis. This paper presents an extension of the cup methods in which a series of dry cup and another series of wet cup measurements are suggested at varying relative-humidity levels outside the cup. Also, a detailed procedure for the data analyses to define the dependence of vapor permeability on relative humidity is presented. The methodology is applied successfully to three materials: perlite insulation board, calcium silicate insulation board, and plywood sheathing.

Interlaboratory Comparison of the ASTM Standard Test Methods for Water Vapor Transmission of Materials (E 96-95)

AbstractAn interlaboratory comparison was initiated by the ASTM C16 Committee on Thermal Insulation to determine the precision of the test method prescribed by ASTM Standard Test Methods for Water Vapor Transmission of Materials (E 96-95). Expanded polystyrene board was chosen as the test material. Nine laboratories completed the measurements according to the dry cup and the wet cup procedures prescribed by the standard. Statistical analyses of the data resulted in the following precision statement for the water vapor permeability:Dry cup method:Permeability of material = 3.1E-12 kg m−1 s−1 Pa−1Repeatability standard deviation (within a laboratory) = 1.6E-1.3 kg m−1 s−1 Pa−1Reproducibility standard deviation (between laboratories) = 4.7E-13 kg m−1 s−1 Pa−1Wet cup method:Permeability of material = 3.4E-12 kg m−1 s−1 Pa−1Repeatability standard deviation (within a laboratory) = 1.7E-13 kg m−1 s−1 Pa−1Reproducibility standard deviation (between laboratories) = 4.1E-13 kg m−1 s−1 Pa−1A specific procedure was uniformly used to analyze the data and to calculate the permeability of the test material from the raw data provided by the participating laboratories. Corrections were made for the resistances offered by the still air layer inside the cup and by the specimen surfaces and for the edge masking details.

Young Children's Causal Inferences

We report 2 experiments that show a striking development between the ages of 3 and 4 years in children's ability to make causal inferences about sequences of events. The task in the first experiment was to work out what had caused the change to an object that started out as odd (noncanonical) in 1 way and ended up as odd in 2 ways--starting, for example, as a broken cup and ending as a wet and broken cup. When asked to choose the instrument that had caused the change, 3-year-olds often selected the instrument that could have caused the initial state (a hammer, in our example) and not the instrument that would produce the change. 4-year-olds hardly ever made this mistake. In the second experiment, the 3-year-olds were able to make the correct choice when the change was from a canonical to a noncanonical state (cup-wet cup) but had much more difficulty when the change was from noncanonical to canonical (wet cup-dry cup). The difference was much smaller in the older group. The first of these tasks can be solved simply on the basis of knowledge that a particular instrument can cause a particular effect without reference to the initial state. The second task requires attention to the differences between initial and final state. We conclude that the ability to make genuine causal inferences develops between the ages of 3 and 4 years.