Small Test Chamber Research Articles

Indoor Emissions from Conversion Varnishes

ABSTRACT Conversion varnishes are two-component, acid-catalyzed varnishes that are commonly used to finish cabinets. They are valued for their water and stain resistance, as well as their appearance. They have been found, however, to contribute to indoor emissions of organic compounds. For this project, three commercially available conversion varnish systems were selected. A U.S. Environmental Protection Agency (EPA) Method 24 analysis was performed to determine total volatile content, and a sodium sulfite titration method was used to determine uncombined (free) formaldehyde content of the varnish components. The resin component was also analyzed by gas chromatography/mass spectroscopy (GC/MS) (EPA Method 311 with an MS detector) to identify individual organic compounds. Dynamic small chamber tests were then performed to identify and quantify emissions following application to coupons of typical kitchen cabinet wood substrates, during both curing and aging. Because conversion varnishes cure by chemical reaction, the compounds emitted during curing and aging are not necessarily the same as those in the formulation. Results of small chamber tests showed that the amount of formaldehyde emitted from these coatings was 2.3–8.1 times the amount of free formaldehyde applied in the coatings. A long-term test showed a formaldehyde emission rate of 0.17 mg/m2/hr after 115 days.

Impact of Early Stage Incomplete Mixing on Estimating VOC Emissions in Small Test Chambers

Abstract Most of the existing emission models developed from small-scale chamber tests assume complete mixing in the chamber throughout the test period. This paper examined this assumption using a Computational Fluid Dynamics (CFD) model. The model simulated the three-dimensional air velocity profiles and Volatile Organic Compound (VOC) concentration distributions from wood stain in a well-designed mixing chamber of 1.0X0.8X0.5 m3. The model used measured data to determine the time-dependent VOC surface concentrations of wood stain. The CFD results show that the VOC concentrations in the test chamber were not uniform in the early stage (about 18 minutes). The first-order decay model using the complete mixing assumption will underestimate the Total VOC (TVOC) emission rates by 65% and 59% in the first 3 minutes and next 15 minutes, respectively. Since wood stain emitted about one third of the VOCs in the first 18 minutes, the impact of incomplete mixing in the early period is significant for calculating the material emissions. Furthermore, the mass transfer coefficient of TVOC calculated by CFD is also compared with that calculated by analogue theory and that calculated by experimental correlation.

Temperature Distribution Induced by Fires in a Small Chamber with Forced Ventilation

Experimental studies on the temperature distribution in forced- ventilation fires at preflashover stage were conducted in a small test chamber with ethanol pool fires. A total number of twenty-eight tests divided into four cases of ventilation conditions were performed. The effect of ventilation rate, ven tilation positions and the size of the pool fire on the heat release rate, temperature rise, height of hot layer and heat flux on the wall surface were studied. The rate of heat release was determined by the methods of mass loss rate and oxygen con sumption. With the calculated heat release rate, the experimental results on the smoke temperature rise were compared with the results predicted by using the energy balance equation as recommended by Deal and Beyler and the correlation relations derived by Foote, Pagni and Alvares. It is found that the equation pro posed by Foote, Pagni and Alvares gave a reasonable prediction on the tempera ture for this set of experiments.

The impact of surface air movement on material emissions

The effects of surface air movement on material emissions were investigated experimentally. A field study was carried out to understand the characteristics of surface air movement in real rooms, and a velocity-controlled test chamber was designed and built, based on the field study results, to provide a uniform mean airflow and boundary layer condition over the test area. An extensive experimental study on the effects of air movement on material emissions was carried out, under different mean flow velocities and turbulence fluctuations, by using the small velocity-controlled test chamber. It was found that material emission rates are a function of the surface air flow conditions: as surface air velocity increases, contaminants from materials deplete faster, the turbulent fluctuation has a lesser effect on material emissions.

The Influence of Temperature on the Emission of Volatile Organic Compounds from PVC flooring, Carpet, and Paint

Abstract The influence of temperature on the emission rate of volatile organic compounds (VOC) from four indoor materials was investigated in a small dynamic test chamber. The materials investigated were two carpets, a PVC flooring and a paint; the temperature range investigated was 23–50°C. The general trend was an increased initial emission rate and an increased decay rate with increasing temperature. The total emitted mass from paint is independent of temperature which means that bake-out is expected to be successful. The total emitted mass of the carpets and the PVC flooring increased with temperature, which suggests an influence of chemical reactions. In these cases, bake-out periods of a few days may be unsuccessful and the exposure of the population may be underestimated when using data from experiments performed at the (lower) standard temperature.

Determination of radon emanation and back diffusion characteristics of building materials in small chamber tests

A methodology has been established to estimate the radon emanation rates and back diffusion rates of different building materials in small chamber tests. The two parameters, emanation rate and back diffusion rate, can be obtained from the growth curve of the chamber radon activity. Small impervious containers with a volume of 14900c.c. were used in the measurement and solid-state radon detectors were used to monitor the chamber radon levels continuously. In the study, the building materials were left inside the chamber for more than 400 hours in order to reach equilibrium radon concentrations. The emanation rates and the back diffusion rates of the samples were found to be fairly constant under the experimental conditions. The emanation rate was determined by the initial slope of the growth curve and the back diffusion rate was determined by the equilibrium value of the activity curve. Leakage of the chamber was estimated by checking the radon free decay rate inside the chamber before each experiment and a correction was included in the calculation. Two kinds of granite and one bare concrete were selected as test samples. The first granite sample had a mean emanation rate of 13.44 Bq · m −2 · hr −1 and a back diffusion rate of 6.89 × 10 −4 hr −1. The second granite sample had an emanation rate of 0.58 Bq · m −2 · hr −1 with a back diffusion rate of 5.40 × 10 −3 · hr −1. The bare concrete had an emanation rate of 8.69 Bq · m −2 · hr −1 and a back diffusion rate of 6.18 × 10 −3 hr −1. The methodology has been found to provide an accurate method of estimating radon emanation and back diffusion characteristics of commonly used building materials.

Stationary loading, fretting and sliding of silver coated copper contacts — influence of corrosion films and corrosive atmosphere

The degradation mechanisms of silver coated copper contacts were studied under stationary loading, reciprocated sliding and fretting conditions. The model contact consisted of two crossed cylinders (Ø = 10 mm) mounted in a small test chamber. Prior to performance testing corrosion films were grown in a large chamber of Battelle class III atmosphere. The tests were performed in four atmospheres, specified with respect to temperature, relative humidity and pollutant gases. The normal force was 20 or 60 N and the contacts were powered with a direct current of 10 A. The study shows that the presence of a thin pre-grown corrosion film on top of the silver coating strongly influences the contact resistance, the friction and the degradation mechanisms of the contact. Generally, the corrosion films reduced the tendencies to adhesion between the contact surfaces, which subsequently reduced the deformation. Moreover, the corrosion films had very different effects in different contact situations. While the impairing effect on the contact resistance was almost neutralized during fretting it was substantial in some sliding cases. In contrast to the pre-grown corrosion film, the test atmosphere was not found to influence the contact performance.

Experimental study on the scaling law of the outgassing rate with a pumping parameter

The outgassing rate of a small test chamber made of type 304 stainless steel has been measured as a function of pumping speed in the range from 0.3 to 200 ℓ/s. The chamber was first exposed to air and then pumped with different pumping speeds for three days at 20 °C without baking. Typical outgassing rates of the chamber are determined from the measurement of steady pressures at the pumping time of 72 h. It is found, as a result, that measured outgassing rates q obey a set of power laws of q1=C1(S/A)m1 and q2=C2(S/A)m2, where S/A is the ratio of pumping speed S to the surface area A of the chamber, C1 and C2 are constants, the exponents m1 and m2 are 0.8282 for S/A⩾10−3 ℓ/s cm2 and 0.4655 for S/A⩽10−3 ℓ/s cm−2. It is shown that the observed power law can be derived from theoretical consideration and is useful to estimate the ultimate pressure of an unbaked vacuum system.

Behavioral manipulation of retrieval in a spatial memory task for Drosophila melanogaster.

A paradigm for operant conditioning of freely walking single Drosophila flies has been described previously. A fly can be conditioned to avoid one side of a small test chamber if the chamber is heated whenever the fly enters this side. In a subsequent memory test without heat the fly continues to avoid the previously heat-associated side. In this experimental design one cannot exclude that flies mark the heated side by an odor that they subsequently avoid during the test. As a final proof for associative learning in the present experiment, flies are trained in one chamber and tested for learning in another, similar one. Handling in the transfer experiment interferes with memory display, even if the fly is returned to the old chamber instead of a new one. Memory can be reactivated, however, by subjecting the fly to an additional brief training (priming), which is too short to establish significant learning in naive flies. For efficient priming, heat has to be applied to the same side as during training in the old chamber. Only then the fly subsequently shows a side preference and avoids the side of the new chamber, which in the old one had been associated with heat. The two chambers are similar but not identical The transfer experiment therefore raises the question as to what the flies use as spatial reference during training and test. In the light, they can be shown to orientate according to visual landmarks associated with the chamber. In complete darkness, where training and memory scores do not differ from those in the light, they are assumed to use a combination of tactile and idiothetic information for orienting.

A new paradigm for operant conditioning of Drosophila melanogaster.

A freely walking single fly (Drosophila melanogaster) can be conditioned to avoid one side of a small test chamber if the chamber is heated whenever the fly enters this side. In a subsequent memory test without heat it keeps avoiding the heat-associated side. The memory mutants dunce and rutabaga successfully avoid the heated side but show no avoidance in the memory test. Wildtype flies can be trained to successively avoid alternating sides in a reversal conditioning experiment. Every single fly shows strong avoidance and a positive memory score. The new conditioning apparatus has several advantages: (1) Statistically significant learning scores can be obtained for individual flies. (2) Learning scores are obtained fully automatically without interference of the experimenter. (3) The procedure is fast, robust and requires little handling. Therefore the apparatus is suitable for largescale mutant screening. (4) Animals are not attached to a hook and thus can easily be used for breeding.

High 222Rn levels, enhanced surface deposition, increased diffusion coefficient, humidity, and air change effects.

Measurements have been made of surface deposition rates for 218Po radon decay products in a small (0.283m3) aluminum test chamber for 222Rn levels from 1 to 1,600 kBq m-3. an increase in macroscopic surface deposition rate has been found to be induced by the high 222Rn concentrations. A distinct 222Rn level threshold has been found below which plateout is constant at the normal rate for ambient residential conditions. Above the threshold, an increase in plateout is observed and the transition quickly reaches a constant, higher plateout. With all environmental conditions remaining constant and varying humidity, the threshold 222Rn level decreases with increasing relative humidity. The rate of rise to the new plateau is found to increase with increasing humidity. For the constant air change rate of ACH = 0.2 h-1, the fraction of airborne 218Po lost by the enhanced plateout was consistently 0.4 +or- 0.25 for seven values of humidity from 8 to 54% RH. For a fixed RH = 40 +or- 2%, it was found that the threshold increases from 5 to 58 kBq m-3 for a change in ACH from 0 1.06 h-1. In converting the deposition data to values of diffusion coefficient D, using Crump and Seinfeld's theory, a very high D of 0.18 cm2s-1 is assumed for ambient air conditions. Results indicate an ambient D = 0.027 cm2s-1. The results may impact on research utilizing high levels in test chambers and diffusion coefficients and attached and unattached fractions, and also for cancer studies using animals with 222Rn levels as much as 10(4) times greater than ambient residential levels.

Development and Evaluation of a Source/Sink Model of Indoor Air Concentrations from Isothiazolone-Treated Wood Used Indoors

Airborne exposure models were developed to account for volatilizing sources and adsorbing surface sinks of isothiazolone biocide volatilized from treated wood into glass chambers and real-world indoor environments. The initial effort described the time-course fate of biocide that becomes airborne and deposits onto the glass surfaces of small ventilated test chambers containing the wood. After the biocide-treated wood was put into a clean-ventilated chamber, the airborne level of biocide built slowly as the biocide initially volatilized and deposited onto the chamber walls. Subsequent re-emission from the glass walls to the air added to the airborne concentration until equilibrium was established between adsorption onto and desorption from the sink, when the airborne concentration leveled off. Adsorption and apparent degradation of the active ingredient on the chamber walls resulted in equilibrium airborne concentrations about a third of those predicted without these mechanisms. Glass and stainless steel t...

Amelioration of Laboratory Conditions for Pigeons (Columba Livia)

AbstractLearning tests in animal psychology are highly standardized with regard to both the formulation of scientific questions and the methods employed to obtain reliable answers. The Skinnerian technique of conditioning rats or pigeons in small test chambers has established itself as the main laboratory method in this field. Despite the undeniable advantages of highly controlled and manipulated test conditions, a number of problems with respect to the welfare of the test animals arise from the standard application of this method. These problems are specified here along with the presentation of new techniques that have been developed at the University of Vienna. The methodological improvements are related to the housing, testing and weighing of the pigeons and ameliorate the conditions these animals previously confronted within the laboratory.

Lack of evidence for context-dependent cocaine-induced sensitization in humans: Preliminary studies

Cocaine-induced behavioral sensitization is the well-documented phenomenon where repeated doses of cocaine elicit increasingly greater effects on motoric activity in rats. Some observations suggest that behavioral sensitization may provide a model for understanding the mechanisms of drug-craving elicited by environmental triggers or cues. The process of fully validating such an animal model for its ability to detect effective anticraving medicines is a difficult and long-term undertaking. As a first step in that direction, we decided to determine if cocaine can produce conditioned behavioral sensitization in humans using a paradigm fairly similar to that used for rodents. Because humans do not react to cocaine with the pronounced motor activation observed in rodents, we measured a variety of end points, including blood pressure (BP), heart rate (HR), respiratory rate, pupil diameter, hormones (prolactin and cortisol), and subjective responses using the questionnaire for drug-related feelings (QDRF) and the EEG. To mimic the home and test cages used in rodent studies, two rooms were used: a small test chamber and a regular room with a window and furnishings. On day 1 each subject received a drug infusion (either saline or 40 mg cocaine IV) in both locations. On day 2, all subjects received an infusion (saline or 25 mg cocaine IV) in the test chamber. All drug infusions were conducted double blind. The paired group received cocaine on both days in the test chamber. The unpaired group received cocaine in regular room on day 1, and cocaine in the test chamber on day 2. A control-1 group received saline at both locations on day 1, and cocaine on day 2 in the test chamber. A control-2 group [4] received cocaine in the test chamber on day 1 and saline in the test chamber on day 2. Conditioned-sensitization was not observed. However, conditioned tolerance was observed for cocaine-induced changes in plasma prolactin levels and diastolic blood pressure. Because rodent studies use cocaine-naive subjects and this study used cocaine-experienced subjects, these data suggest that prior experience with cocaine may alter it ability to poduce sensitization. Viewed collectively, the present investigation suggests caution in the design of both human and animal studies.

Wideband reverberation reduction in long-time acoustic signals produced by transducers in small test chambers

For times long compared to the acoustic wave transit time in a test tank, the signal from point acoustic sources may be dominated by internal reflections and the modal response of the experimental tank in which experiments are performed. If the free-field source behavior of the acoustic source is desired, it can be extracted by taking advantage of special properties of the source/tank system. The transducer can be operated in a manner which permits characterization of the tank response; then the processed results can be used to reduce the effects of the tank response in the signals of interest. Spectral methods for this signal processing will be described and illustrated. The result is that signal characteristics in spectral regions of interest can be more clearly resolved and enhanced. [Work sponsored by U.S. Navy.]

Adsorption Of Selected Volatile Organic Compounds On A Carpet, A Wall Coating, And A Gypsum Board In A Test Chamber

The adsorption of vapours of different volatility and polarity on three materials widely used indoors (carpet, gypsum board, wall coating) has been investigated in small test chambers, in order to study methodological aspects and to estimate the importance of the phenomenon for human exposure assessments. The output of the models used, with rate constants describing two different sinks, is discussed. The experiments show that: a) adsorption seems to occur to at least two different sinks with different rate constants in the same material; b) generally adsorption increases with the boiling point of the compounds, but it depends also on other physicochemical properties, such as the chemical functionality, as well as on the sorbent material: e.g. the two alkanes n-decane and n-dodecane show a higher k3/k4 ratio on carpet than on gypsum board, whereas the opposite is observed for the two alcohols 2-butoxyethanol and 2-ethylhexanol

A simple fast pulse gas valve using a dynamic pressure differential as the primary closing mechanism

In this article we describe a simple fast pulse gas valve developed for use in a plasma discharge experiment. The valve delivers 1017–1019 molecules per pulse varied by changing the voltage on the electromagnetic driver power supply. Valve pulse widths are observed to be less than 300 μs full width at half maximum with a rise time of less than 100 μs resulting in a maximum gas flow rate of ∼1022 molecules per second. An optical transmission technique was used to determine the mechanical opening and closing characteristics of the valve piston. A fast ionization gauge (FIG) was used for diagnosis of the temporal character of the gas pulse while the total gas throughput was determined by measuring the change in pressure per pulse in a small test chamber with a convectron tube gauge. Calibration of the FIG was accomplished by comparing the net change in pressure in a large chamber as measured by the FIG to the net change in pressure in a small test chamber as measured by the convectron tube gauge.

Optical imaging chamber for x-ray astronomy

The light emitted by electron avalanches in a parallel plate chamber can be used to image the tracks of photoelectrons liberated by the interaction of an incident X-ray with the gas filling the chamber. The differing morphologies of photoelectron tracks and high-energy charged particle tracks can be used for background rejection. The initial direction (before scattering) of the liberated photoelectron also contains information about the polarization of the incident radiation. We have built a small test chamber with which we have imaged photoelectron tracks using an intensified CCD camera. Our results show that optical imaging could be used in a hard X-ray imaging polarimeter useful for astronomy.

Small Chamber Tests and Headspace Analysis of Volatile Organic Compounds Emitted from Household Products

Small Chamber Tests and Headspace Analysis of Volatile Organic Compounds Emitted from Household Products

The Interaction of Vapour Phase Organic Compounds with Indoor Sinks

The interaction of indoor air pollutants with interior surfaces (i.e., sinks) is a well known, but poorly understood, phenomenon. Studies have shown that re-emissions of adsorbed organic vapours can contribute to elevated concentrations of organics in indoor environments. Research is being conducted in small environmental test chambers to develop data for predicting sink behaviour. This paper reports on the development of sink models based on fundamental mass transfer theory. The results of experiments conducted to determine the magnitude and rate of adsorption and desorption of vapour phase organic compounds for several materials are presented. Five materials were evaluated: carpet, painted wallboard, ceiling tile, window glass, and upholstery. Two organic compounds were tested with each material: tetrachloroethylene (a common cleaning solvent) and ethylbenzene (a common constituent of petroleum-based solvents widely used in consumer products). The results of the experimental work are presented showing the relevant sink effect parameters for each material tested and comparing the sorptive behaviour of the two organic compounds evaluated. An indoor air quality (IAQ) model was modified to incorporate adsorption and desorption sink rates. The model was used to predict the temporal history of the concentration of total vapour phase organics in a test house after application of a wood finishing product. The predicted results are presented and compared to measured values. Suggestions for further research on indoor sinks are presented.