Formaldehyde emission methods

Particleboard-Determination of Formaldehyde Emission under Specified Conditions Method Called Formaldehyde Emission Method," European Standard Situation Report EN-N76E-1983, European Committee for Standardization, Brussels, 1983... 

Plotting 1/Cg against n/a, gives a straight line, from which both concerned board properties are gathered. Graphs show that independent of the size of the apparatus, this statement is backed up quite well. Various examples that influence both those parameters illustrate the use of this formaldehyde emission method. 

To illustrate that the relation with the perforator values (standard formaldehyde emission method, EN 120) is very poor, these values are given in the Table as well. 

Particle boards - Determination of formaldehyde emission under specified conditions Method called Formaldehyde Emission Method European Committee for Standardization, CEN 1984 ... 

Product tests. Clearly, the best product test is full-scale testing of finished panels under actual use conditions. This has been done (27,38) but is expensive, because several full-sized panels of each product must be pre-conditioned at constant temperature and humidity for at least a week. The next best approach is to test product samples in air chambers under standardized conditions. A summary of such methods is contained in Table I. A very large effort has been made over the last three decades world-wide to develop quick, reliable and meaningful product tests. Wittmann (16), Zartl (20), Plath (17), Verbestel (1, Neusser (21,22), Roffael (25), HUD, the U.S. Forest Products Industry (39,40), many standaraization organizations (41-43) and others have published many viable methods, but the testing involves a combination of complex factors and there is simply no single test that fulfills everybody s specific needs. Table I list some of the currently accepted test methods for formaldehyde emission from particleboard, plywood and medium density fiberboard. 

Manufactured Home Construction and Safety Standard, Air Chamber Test Method for Certification and Qualification of Formaldehyde Emission Levels," U.S. Code of Federal Regulations, Vol. 24, Part 3280.406, (U.S. Department of Housing and Urban Development), and F eral Register, Vol. 48, pg 37136-37195, 1983. 

Large Scale Test Method for Determining Formaldehyde Emission from Wood Products Air Chamber Method, FTM-2" National Particleboard Assocaiton, Hardwood Plywood Association, U.S. Department of Housing and Urban Development, Federal Register, 1982, 48, 37169. 

Small scale test method for determining formaldehyde emissions from wood products, two-hour desiccator test, FTM 1, Reston, VA. 

G. Gramp, W. Groah. "Evaluation of the relationship between formaldehyde emission from particleboard mobile home decking and hardwood plywood wall paneling as determined by product test methods and formaldehyde levels in experimental mobile homes." U.S. Dept. of Housing and Urban Development, 1982. 

Roffael (15) measured formaldehyde emissions from a phenolic particleboard using the WKI-Method which involves suspending small samples over 50 cm of distilled water in tightly closed polyethylene bottles and measuring formaldehyde levels in the water after varying times. Temperatures were maintained at 42 C. This work indicated that formaldehyde release from the phenolic particleboards ceased after a relatively short reaction period (approximately 96 hours). This finding is consistent with the resin stability considerations discussed previously under theoretical considerations. 

Large-Scale Test Method For Determining Formaldehyde Emissions From Wood Products — Large Chamber Method, FTM 2-1983 National Particleboard Association Gaithersburg, MD, 1983. 

An automated and microprocessor-controlled flow injection analysis system was developed for formaldehyde emission measurements. This system was based on the modified pararosaniline method and a sampling rate of about 40 samples/hour was obtained. 

The slopes of the calibration plots, 60.87 fluorescence unit per Pg/ml for enzymatic fluorometric method I and 120 fluorescence unit per pg/ml for enzymatic fluorometric method II, show that method II is approximately twice as sensitive as method I. This is due to formation of the intensely fluorogenic resorufin in method II. The higher sensitivity and lower detection limit of the enzymatic fluorometric method II will have potential applications in air sampling of formaldehyde emissions since sampling time can be reduced. 

The measurement of formaldehyde release from wood products Involves the collection of formaldehyde vapor in the test chamber using a suitable absorbing solution and then analyzing the formaldehyde collected. For many years, formaldehyde emission measurements were carried out using the desiccator test sampling method due to... 

These test chambers can be incorporated to the enzymatic methods for formaldehyde determination. Formaldehyde emissions of a product, or mix of products, to the ambient air can be collected in distilled water or 1% sodium bisulfite as the absorbing solution. After collection, formaldehyde samples are analyzed as described above. In the mobile home simulator test method (2J, double or triple impingers, which are placed in series, should be used in order to collect all of the formaldehyde vapor. The test conditions should simulate the actual environment. Several factors such as temperature and relative humidity of the system including the specimens and background of formaldehyde in the test chamber, affect the precision and accuracy of the results. It has been shown that a 7 C change in temperature doubles the emission level (L). The temperature of the test chamber should be... 

The enzymatic methods described in this paper are not only more specific but also more sensitive than the chromotropic acid method. These methods can be used for the measurement of formaldehyde emission from wood products as well as formaldehyde exposure in the workplace and in indoor environments. 

Analytical Method for the Determination of the Formaldehyde Emission from Chipboard related to the Concentration in Living Environments Methanol Chemie Nederland vof, Delfzijl (1982) Myers, G.E. Nagaoka, M. Forest Prod.J. 1981, 31(7), 39-44. Hoetjer, J.J. Holz als Roh- und Werkstoff 1981, 39(9), 391-393. 

Hoetjer, J.J. Experiences with measurements and analytic method for the determination of the formaldehyde emission from chipboard related to the concentration in living environments . Methanol Chemie Nederland vof Delfzijl 1982... 

Determining Formaldehyde Emission from Wood Products" FTM-2 - 1983 (16). In this method, particleboard and hardwood plywood paneling are tested under the following conditions ... 

Singh Walcott, J. St. Pierre, C. Ferrel, T. Garrison, S. Groah, w. "Evaluation of the Relationship Between Formaldehyde Emissions from Particleboard Mobile Home Decking and Hardwood Plywood Wall Paneling Determined by Product Test Methods and Formaldehyde Levels in Experimental Mobile Homes" Clayton Environmental Consultants, Inc., Report, Prepared on Contract No. AC-5222, H.U.D., March, 1982. 

Formaldehyde emission from particleboard has been studied at our laboratory for over 15 years. We search for an answer to the following question Given the fact that amino-resin bonded wood products have the ability to release formaldehyde into indoor air when they are in use, what simple and rapid analysis method can be used at the time of manufacture to predict formaldehyde release under use conditions as quantitatively as possible Obviously, the chosen method needs to be applicable for all types of boards that are available on the market. 

At this point of the study it is not possible to improve our knowledge of the emission trends with this method. However, given that the formaldehyde emission from a particleboard must decrease with time, we decided to measure this effect. Two sets of experiments were carried out parallel to each other for one year at 23 L and 65% RH, 80% RH, or 30% RH. The boards were tested at regular intervals by both the perforator method and the gas flow... 

One month after pressing, the boards were cut and triplicate samples for each duplicate board tested according to the dessicator method, using Purpald solution and a colorimeter, for formaldehyde emission over a period of 24 hours and 30 minutes Purpald development. After this initial assessment the samples were placed in a laboratory fan-exhaust oven at a temperature of 50 C to accelerate the test for a period of two months. The samples were tested at regular intervals of three weeks over the two months period. The formaldehyde emission results obtained are shown in Table I. 

After a discussion of mechanisms for the liberation and subsequent emission of formaldehyde from particleboard, methods to assess the extent of these processes are described. Data are presented for the formaldehyde emission from particleboard with various surface treatments. These data were obtained by a laboratory method and by large climate chamber measurements and show that some of the surface treatments studied constitute very efficient diffusion barriers and considerably reduce the formaldehyde emission rate. 

Dyno has contributed to the development of a method, named the Bell method, for the quantitative determination of the formaldehyde emission from a panel surface ( 5). A glass flask or bell having a plane flange is placed on the surface to be measured. A tight sealing between the flange of the bell and the panel surface is very important. The air can be kept in circulation by means of a membrane pump, pumping about 2 liters per minute in a closed loop, which also contains a gas burette. After a predetermined time the formaldehyde concentration of the air in the gas burette is determined by a sensitive analytical method. 

However, it appears that limiting values are being proposed in several European countries, even though we know that it is still difficult to measure and enforce the proposed standard levels and even though the proposed measurement methods have been challenged. In France we want to be certain that we can enforce a standard before we finalize methods and set specific values. Therefore, we still continue to work towards a better understanding and definition of the formaldehyde emission process. 

In an earlier chapter, Romeis has shown that there is presently no laboratory method that allows meaningful prediction of formaldehyde emission from particleboards. Why is particleboard so important In Europe, this panel represents the biggest use of aminop last resins. 

The problem with current laboratory methods is that they only measure formaldehyde at a single time point under equilibrium conditions. In contrast, real-life use of particleboard involves climatic shocks. This was well illustrated by a study at the center for surface technology In Haarlem (3). Figure 1 shows that changes in air humidity and temperature greatly and promptly influence formaldehyde emission. Thus, while laboratory tests allow a qualitative evaluation of the emission risk, they do not permit quantitative extrapolation to real-life conditions. 

The current methods for measuring formaldehyde emission from board are expensive, often undependable, and they do not permit a reliable quantitative extrapolation to real-life conditions at the present state of research. 

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