Particleboard test chamber

For bare particleboards in suitable test chambers, mass transfer resistances are usually found to lie between 1,500 and 10,000 s/m. When there is no internal circulation or when there is insufficient turbulence, it is not uncommon to find an extra mass transfer resistance for the gas phase of 12,000 s/m at a ventilation rate of 0.75 per hour. A more detailed estimation is given in the summary. 

Table IX presents chamber data obtained in only one large test chamber identified as A on medium density fiberboard made at one plant. A medium density fiberboard "set" is a specific production run. The columns are labeled the same as the particleboard Table VIII described above. The "Normalized Chamber Concentration" is based on a 0.6 ppm formaldehyde concentration at an N/L ratio of 0.96. The choice of 0.6 ppm concentration is purely arbitrary. Figure 8 graphically represents the normalized formaldehyde chamber concentrations to loadings at air changes of 0.5, 1.0 and 1.5. The points which define the curves are averages of the normalized concentrations.

Figure 12 is a graphical representation of thirty-three individual chamber round robins between Georgia-Pacific s chambers in Decatur, Georgia and Sacramento, California to various test chambers identified as A, B, C, D. The data obtained in this three year study were based on both an exchange of the same boards or statistically sampled matched board sets. This data includes 10 paneling sets, 15 particleboard sets, 8 medium density fiberboard sets. There were four tests that involved testing the very same boards. 

Upon completion of the chamber test, the hardwood plywood paneling or particleboard is removed and 12 each 7.00cm x 12.7 cm specimens are randomly cut from each board loaded into the chamber. For the surface monitor (FSEM) and the small scale test chamber(SSTC), one 30.5cm X 30.5cm board is cut from each board loaded in the chamber. These samples are immediately tested by the Equilibrium Jar for particleboard or the Two Hour Desiccator or FSEM or SSTC for all wood product types. The values obtained from each test are averaged and are then compared to the chamber concentration observed for that loading and air change rate. 

National Particleboard Association, Eafge Chamber Test (FTM2-1985) OSHH 52protocol, private communication, June 27,1988. 

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. 

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. 

In-plant quality control and routine acceptance testing by property verification organizations such as the Hardwood Plywood Manufacturers Association and the National Particleboard Association require a method more efficient than the chamber for routinely monitoring trends in emission characteristics of products. The relationship between chamber and the small scale desiccator test observations is illustrated by a series of 76 tests accomplished during the past year on hardwood plywood wall panel products at a chamber loading rate of 0.29 sq ft per cu ft ... 

National Particleboard Association, Hardwood Plywood Manufacturers Association, October 10, 1983. Large scale test method for determining formaldehyde emissions from wood products, large chamber method, FTM 2, Reston, VA. 

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

To explain this, it can be argued that a not inconsiderable increase in resistance to mass transfer has been set up in the gas phase, which in fact may vary from situation to situation. Such situations are indeed normal in everyday practice. This explains why in practice, especially at low ventilation rates, much lower concentrations are found, than would follow from measurements done in climate chambers with good circulation. Such intensive circulations remain absolutely necessary if determination of the characteristic particleboard parameters is wanted, independant of the test environment. 

The U.S.Department for Housing and Urban Development s rule 3280.308 established formaldehyde emission standards for particleboard and hardwood plywood paneling used in mobile homes. These standards took effect February 11, 1985. The certification program under this rule requires each manufacturer to develop a quality control in-plant testing program that relates to tests conducted in a large scale environmental chamber. 

Table VIII presents chamber data on underlayment particleboard, mobile decking particleboard, and industrial particleboard obtained from four different chambers identified A, B, C and D. A particleboard "set" is a specific production run of a particleboard type. The observed concentration is the formaldehyde level actually determined in the chamber for a specific loading and air change rate. "N" represents the air change rate (number per hour). The column labeled "L" is the loading (m2/m3) that the test was conducted. The column "N/L" ( m/hr) is the ratio of air change rate to the loading. Finally, the column labeled "Normalized Chamber Concentration" is the actual chamber concentration (first column) normalized to 0.3 ppm at N/L = 1.16. The 0.3 ppm chamber...

Thirty-one particleboard sets of type 1 were obtained from all of our particleboard plants. As you can see in Figure 13, there is a cloud of points below 0.3 ppm chamber and a group of three points around 0.4 ppm. The cloud of points around 0.3 ppm represents current production which is made to meet the H.U.D. particleboard standard. The three points around 0.4 ppm are from a special plant test performed to define the shape of the Equilibrium Jar/chamber correlation curve. The reasons we can plot all the data points from all the plants are 1) all plants have the same process 2) we have a historical data base. 

Figure 14 provides a graphical representation of 27 chamber tests conducted on a variety of veneer, print, a paper overlay finished hardwood plywood paneling. Even though it is not shown, a breakdown by different product type did not affect the correlation by anymore than 5%. As with particleboard, the cloud of points below 0.2 ppm represents current production made to meet the H.U.D. hardwood plywood paneling standard (0.2 ppm chamber). The group of points between 0.24 and 0.36 ppm chamber are from earlier chamber studies needed to define the curve. 

Particleboard and paneling samples were pulled from the manufacturing line shortly after it was made or finished. A portion of the boards was analyzed by the plant Q.C. laboratory personnel without being told the purpose of the test. The boards were transported to the Decatur laboratory within 24 hours after manufacture. The boards were conditioned for 24 hours upon arrival at the laboratory, and the following day they were inserted into the chamber. 

Equilibrium jar Q.C. test for a G-P particleboard type 1 correlates to large scale chamber. 

Newton, L. "Formaldehyde Emissions from Wood Products Correlating Environmental Chamber Levels to Secondary Laboratory Tests" International Particleboard Symposium No. 16 Washington State University, Pullman, 1982. 

The finishes in table 2 were not tested in the climate chamber/ because the necessary equipment for the controlled application of them to full-size particleboards was not available. 

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