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Eingeladener Vortrag
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Emission testing of products is currently a rapidly increasing field of measurement activity. Labelling procedures for construction products are based on such emission test chamber measurements and hence measurement performance should be verified. A suited procedure for this purpose is the testing of one unique homogenous material in different laboratories within a Round Robin Test (RRT). Therefore, it is useful to have a reference material which can be used within inter-laboratory studies or as part of the quality management system to ensure comparable results. Several approaches on the development of reproducibly emitting materials have been published. These have in common only to emit a single VOC – toluene. Two further research studies carried out by BAM aimed to develop reference material for emissions testing containing one or more VOC in a single material. The first approach was a doped lacquer with Volatile and Semi-Volatile Organic Compounds (VOC/SVOC) and the second was Thermoplastic Polyurethane (TPU) or a Squalane/Paraffin mixture. Results received with the lacquer based material were presented in more detail.
Design of Reference Materials for Proficiency Tests for Measurements in Emission Test Chambers
(2017)
Emission testing of products is currently a rapidly increasing field of measurement activity. Labelling procedures for construction products are based on such emission test chamber measurements and hence measurement performance should be verified. A suited procedure for this purpose is the testing of one unique homogenous material in different laboratories within a Round Robin Test (RRT). Therefore, it is useful to have a reference material which can be used within inter-laboratory studies or as part of the quality management system to ensure comparable results.
Any commercially available product on the market can be used as reference material, provided it is thoroughly characterised. However, these materials often emit only a few and material specific VOCs and appropriate homogeneity is not given. Therefore, alternative materials should be found.
Several approaches on the development of reproducibly emitting materials have been published. These have in common only to emit a single VOC – toluene. Two further research studies carried out by BAM aimed to develop reference material for emissions testing containing one or more VOC in a single material. The first approach was a doped lacquer with Volatile and Semi-Volatile Organic Compounds (VOC/SVOC) and the second was Thermoplastic Polyurethane (TPU) or a Squalane/Paraffin mixture. Currently, the second approach is not at a level that it could be tested within a RRT.
Important requirements for the production of a reference material were repeatability (homogeneity), reproducibility, long-term stability in terms of compound release and transport stability. The emission rates should be high enough to obtain well measurable chamber air concentrations at standardised test conditions.
The lacquer samples were prepared by weighing portions of a water-based lacquer to which defined amounts of the pure analytes were added. Defined amounts of the lacquer mixture were filled into Petri dishes and cured under standard conditions (23 °C and 50% relative humidity). Reproducible emissions were obtained when the storage time of the cured material was not longer than four weeks. The concentrations were analyzed 7 days after loading of the material into the chamber.
Two RRT were conducted by use of the lacquer system. Here, the laboratories had to identify and also to quantify the compounds. The relative standard deviations obtained were typical for such a kind of test. More than 50 participants reported results.
Since some volatile organic compounds (VOC) are dangerous to human health whilst others cause harm to the environment by influencing the oxidative capacity of the atmosphere, the overall aim of the KEY-VOCs project is to improve the measurement infrastructure for Key Volatile Organic Compounds in indoor and outdoor air. This is done by providing traceable and comparable reference gas standards and by validating new measurement systems in support to the air monitoring networks.
Museums worldwide are equipped with different display cases. Exhibit display cases should protect cultural objects from dust as well as from mechanical and physical damage. To ensure a stable climate inside the display cases, a low air exchange rate is maintained. Typically air exchange rates are often smaller than 0.1 d 1, which can result in rising concentrations of potential harmful immissions inside of the display cases due to emissions from materials. Especially high concentrations of organic acids, which can emit from e.g. sealing materials, can produce damage of cultural objects. In 2012 BAM introduced a procedure witch is called: BEMMA-Scheme (Bewertung von Emissionen aus Materialien für Museumsausstattungen) which stands for: “Assessment of Emissions from Materials for Museum Equipment”. Micro chambers are used for VOC emission tests of display case construction materials, e.g. textiles, plastics, sealing material, coatings and others. Each sampling procedure is carried out in duplicate. Emissions like formic acid, acetic acid, formaldehyde and oximes are excluded and the sum of emissions of VVOCs, VOCs and SVOCs is limited. For a positive assessment all listed criteria must be fulfilled; otherwise the display construction material fails the BEMMA scheme. The BEMMA scheme is not a guarantee for an emission free display case, but a necessary requirement for the choice of suitable materials for emission and immission reduced display cases. The basic evaluation for the values used for first assessments were a ZIM-project with nearly 100 tested materials. In-between more than 100 new materials were tested and enlarged the knowledge about material emissions from display case materials. Mainly silicone sealing materials were tested due to the fact that this group of material have the highest emissions. With regard to the testing procedure only construction materials were evaluated, not the display cases their self. Nevertheless in combination with the certificate also designed by BAM additionally the further steps of construction can be taken into account. So other factors such as age and storage time of materials, tightness respectively air change rate, air condition or ventilation of display cases can be included in the evaluation.
Mit dem BEMMA-Verfahren lassen sich flüchtige organische Verbindungen aus modernen Werkstoffen, die in mittel- oder unmittelbarem Kontakt mit historischen Materialien des Kunst- und Kulturgutes stehen, untersuchen und bewerten. Das Verfahren wurde im Rahmen eines AIF-Vorhabens und der Untersuchung von über 100 unterschiedlichen Materialien entwickelt. Weiterhin wurden mit den gewonnenen Ergebnissen und einigen zuvor bereits identifizierten Problemstoffen wie Essigsäure, Formaldehyd oder Oxime aus den Vorhabenerkenntnissen Bewertungskriterien erarbeitet. Die Vitrinenbaumaterialien, nicht die Vitrine, werden im Hinblick auf ihre Emissionen bewertet, wobei z. B. Holzwerkstoffe nicht bewertet werden, zumal diese meist mit Formaldehyd ein Emissionsproblem hätten. Der Einsatz von Materialien für Vitrinen, die gemäß BEMMA-Schema getestet wurden und die die Emissionswerte erfüllen, soll die Herstellung möglichst emissionsarmer Vitrinen ermöglichen. Kernstück des BEMMA-Schemas ist die Bewertung aller Messergebnisse gemäß dem im Folgenden dargestellten Untersuchungsablauf:
1. Beladen der µ-Kammer; 2. Probenahme der flüchtigen, kurzkettigen, organischen Säuren (ca. 0,5 bis 1 Stunde nach der Beladung für ca. 20 Stunden, 30 Liter Probenahmevolumen); 3. Probenahme der VOCs mit Tenax® (ca. 10 Minuten, 0,25 Liter Probenahmevolumen); 4. Probenahme Oxime und Piperidin-Derivate† mit Tenax® (ca. 40 Minuten, 1,0 Liter Probenahmevolumen); 5. Probenahme der Aldehyde und Ketone (für ca. 20 Stunden, 30 Liter Probenahmevolumen) Dabei werden 4 Sammlersysteme beladen und anschließend analysiert.
Die mit dem BEMMA Schema entwickelten Summenwerte für flüchtige organische Stoffe sind im Wesentlichen vor dem Hintergrund der Emissionsminimierung aufgestellt worden. Es gibt für viele VOC keine eindeutige Wechselwirkung mit den Objekten in der Vitrine, zumal diese auch aus vielen verschiedenen Werkstoffen bestehen können und ein VOC nicht mit all diesen reagieren wird. Grundsätzlich „verdächtig“ sind natürlich alle reaktiven Stoffe, wie z. B. Isocyanate. Diese werden aber aus gut gelagerten oder ausreichend belüfteten Baumaterialien für Vitrinen nicht abgegeben. Anorganische Schadgase können zwar in der Umgebungsluft verstärkt auftreten - sind aber aus Baumaterialien nicht zu erwarten. Daher kann das BEMMA-Schema auch nur für einen Teil der luftgetragenen Schadstoffe eine sinnvolle Aussage treffen.
Eines der Probleme bei der Bewertung vieler Kleb-/Dichtstoffe ist die Emission cyclischer Siloxane. Deren Schädigungspotential einzu¬schätzen wäre eine wichtige Aufgabe, um an dieser Stelle mehr Klarheit bei der Bewertung zu bekommen.
Emission testing of products is currently a rapidly increasing field of measurement activity. Labelling procedures for construction products are based on such emission test chamber measurements and hence measurement performance should be verified. A suited procedure for this purpose is the testing of one unique homogenous material in different laboratories within a Round Robin Test (RRT). Therefore, it is useful to have a reference material which can be used within inter-laboratory studies or as part of the quality management system to ensure comparable results. Several approaches on the development of reproducibly emitting materials have been published. These have in common only to emit a single VOC – toluene. Two further research studies carried out by BAM aimed to develop reference material for emissions testing containing one or more VOC in a single material. The first approach was a doped lacquer with Volatile and Semi-Volatile Organic Compounds (VOC/SVOC) and the second was Thermoplastic Polyurethane (TPU) or a Squalane/Paraffin mixture. Results received with the lacquer based material were presented in more detail.
Since some volatile organic compounds (VOC) are
dangerous to human health whilst others cause harm to the environment by influencing the oxidative capacity of the atmosphere, the overall aim of the KEY-VOCs project is to improve the measurement infrastructure for Key Volatile Organic Compounds in indoor and outdoor air. This is done by providing traceable and comparable reference gas standards and by validating new measurement systems in support to the air monitoring networks.
Volatile Organic Compounds (VOC) are ubiquitous in the indoor air, since they emit from materials used indoors. Investigations of these materials are mostly carried out in test chambers under controlled climatic conditions. Quality control of these test chamber measurements is important but there is a lack of commercially available homogenous reference materials as required for round robin tests or quality assurance of laboratories. The approach of the present study is the impregnation of a supporting material with VOC, which are reproducibly released in measurable chamber air concentrations under standardised test conditions. A polymer made of Thermoplastic Polyurethane (TPU) was chosen as carrier material. It was impregnated with the VOC trimethyl pentanediol isobutyrat (texanol).
Volatile Organic Compounds (VOC) are ubiquitous in the indoor air since they are emitted from materials used indoors. Investigations of these materials are mostly carried out in emission test chambers under controlled climatic conditions. Reference materials are an important tool for quality assurance/Quality control of emission test chamber measurements but so far they are not commercially available. In this study, a new approach was tested to develop an appropriate reference material with homogenous and reproducible emission of the VOC with well measurable air concentrations in emission test Chambers larger than 20 L at air change rates of 0.5 - 1 /h.
Thermoplastic Polyurethane (TPU) was selected as Matrix material which was impregnated with 2,2,4- trimethyl-1,3-pentanediol monoisobutyrate (texanol) as test VOC using compressed carbon dioxide. An optimization of the impregnation parameters such as temperature, pressure, time, VOC injection volume and TPU sample size was performed until the targeted area specific Emission rate (SERa) value was reached. Further aspects like process control, storage effects and correlation of the sample size to the emission rate were investigated. It was found that the SERa immediately after sample preparation were not reproducible between the batches but became unified 10 days after loading into the test chamber indicating the necessity of aging before use. SERa between 13,000 and 18,000 mg m-2 h-1 were obtained, and the impregnated materials could be well stored in aluminum-coated polyethylene foil for at least seven weeks without significant losses. Furthermore, the impregnation of styrene and the SVOC 2,6-diisopropylnaphthalene was tested.
Recent research into emissions of (semi-)volatile organic compounds [(S)VOC] from solid materials has focused on the development of suitable reference materials for quality assurance/quality control of emission test chamber measurements, which fulfill requirements such as homogenous and reproducible (S)VOC release. The approach of this study was to find a method for preparation of a material with predictable (S)VOC emission rates. AVOC (styrene) and an SVOC (2,6-diisopropylnaphthalene, DIPN), loaded into either vacuum grease or a 1:1 mixture of paraffin/squalane, have been tested. For the prediction of the emission rates, a model using the finite element method (FEM) was created to simulate the (S)VOC emission profiles. Theoretical and experimental results obtained in a Micro-Chamber/Thermal Extractor (μ-CTE™) and in 24 L emission test chamber measurements were in good agreement. Further properties were investigated concerning the material applicability, such as shelf life and inter-laboratory comparability. The maximum relative standard deviation in the inter-laboratory study was found to be 20%.