Formaldehyde concentration chamber

Figure 4.10 Chamber concentration/time profiles for four kinds of dry building materials At the beginning of the test, a dose of formaldehyde was injected into the chamber air, the measurement stopped when the chamber formaldehyde concentration hardly changed (Zhang et al., 2007a).

Figure 4.15 The chamber formaldehyde concentration decay curves (a) an annular PCO reactor without fins, (b) an annular PCO reactor with six fins.

Applying fins coated with titania is an effective way to enhance the formaldehyde removal performance (Mo et al., 2008b). In order to compare the formaldehyde removal performance of annular photocatalytic reactors with and without the aforementioned fins, the PCO reactors without and with the fins operated in a sealed stainless steel chamber with formaldehyde in its air, respectively. Figure 4.15 shows the chamber formaldehyde concentration decay curves (a) an annular PCO reactor without fins, (b) an annular PCO reactor with six fins. It can be seen that the reactor with fins is more efficient than that without. The reason and the analysis are presented by Mo et al. (2008b) in detail. 

Formaldehdye generation and recovery studies 3.) Air exchange measurement techniques 4.) Preconditioning of test boards 5.) Temperature effect on chamber formaldehyde concentrations 6.) Relationship of popular quality control test methods to the large chamber 7.) Loading, air exchange rate, and wood product combination effects on chamber formaldehyde concentrations 8.) Chamber Round Robin studies between Georgia-Pacific s chamber and other outside lab chambers 9.) Chamber concentrations and its relationship to actual field measurements. 

N.B.S. researchers believe the 1.5 meters per minute face velocity is realistic of actual air flow in a dwelling. Our chamber studies indicate that face velocities become an important factor in determining final chamber formaldehyde concentration whenever the board is classed as a high emitter. High face velocities for high emitters appear to promote higher chamber concentrations. However, high face velocities across low emission boards do not appear to appreciably affect chamber concentrations. 

Figure 6. Temperature effect on chamber formaldehyde concentration ...

Figure 10. Effect of two dissimilar wood products on chamber formaldehyde concentration.

Effects of loading and air exchange rates on chamber formaldehyde concentrations can be predicted. 

The experimental system is shown in Figure 4.9. The tested samples are placed in an airtight chamber whose volume is 301. By using a water bath, the chamber and air temperature can be maintained at the desired temperature. Tests were conducted at four air temperatures 18 0.5 °C, 30 0.8 °C, 40 0.8 °C and 50 0.6 °C, with air humidity uncontrolled but in the range 60 8%. After the system reaches thermal equilibrium, a dose of saturated formaldehyde vapor is injected into the chamber and thereafter the instantaneous concentrations of formaldehyde in the chamber are continuously recorded by an INNOVA-1312 until the equilibrium concentration C(y is reached at the equilibrium time, There are several reasons for applying a real-time photo-acoustic monitor to measure the instantaneous chamber compound concentrations for this research. First, its sampling volume is small and the air can be returned into the chamber... 

Formaldehyde is absorbed by the tissues of the respiratory traet during inhalation exposure in several species. Heck et al. (1985) determined the fate of inhaled formaldehyde in humans. Four men and two women were exposed to a 1.9 ppm air concentration of formaldehyde in a large walkin chamber for 40 minutes. Shortly before and shortly after the exposure, venous blood samples were taken from each person (each person served as his/her own control) and the blood was analyzed for formaldehyde content. Mean venous blood formaldehyde concentrations in humans prior to exposure showed a blood concentration of 2.61 0.41 g/g of blood. Individual variability was markedly present. Immediately after a 40-minute exposure, mean blood concentration of formaldehyde was 2.77 0.28 g/g of blood. There was no significant difference between pre- and postexposure blood concentrations of formaldehyde at the formaldehyde air concentrations tested in this study. This result suggests that formaldehyde was absorbed only into the tissues of the respiratory tract. The absence of increased formaldehyde concentrations in the blood is likely due to its rapid metabolism in these tissues and/or fast reaction with cellular macromolecules. 

Figure 3. Formaldehyde concentration in I m air chamber containing school chair made from plywood and solid wood with I m surface (80% painted). Age of furniture is 4 months, 3 years, and 12 years ( ).

Reduced sample loadings in the dynamic chamber led to decreased formaldehyde concentrations in the chamber as noted or predicted previously by others (17, 20-22). This resulted in increased release rate coefficients (yg m 2 day"b. Samples analyzed at 1.4 and 1.6 m2 of product surface area/m of chamber volume chamber loadings had formaldehyde chamber concentrations of 28-32% of the calculated equilibrium air concentrations of formaldehyde (17), suggesting better relative ventilation than that at higher chamber loadings. 

The GEM method is based upon the assumption that the size and shape of the testing chamber does not influence the emission. During the testing the formaldehyde concentration in the chamber will rise and stabilize at a steady state concentration. At constant climate the steady-state concentration or emission rate from the test object depends on the relation between the loading factor and the air change rate. Good air circulation in the chamber is also essential ( ). 

To stabilize temperature, relative humidity, and formaldehyde concentrations within the chamber, we have found it necessary to have an air deflector (Item 13) placed between the back wall and a floor fan (Item 14) in such a way that the air flow from the floor fan is directed counter-current to the air flow movement from the air cooler s blower. Formaldehyde recovery studies, smoke stick evaluations, and formaldehyde determinations performed in several locations within the chamber have substantiated the efficiency of this mixing technique. 

Formaldehyde Measurement Methods For Chamber Field Concentrations... 

Georgia-Pacific Recovery Studies. For us to perform our own recovery study, we refined and developed a syringe pump method for generating formaldehyde concentrations within our large scale test chamber. This method was originally created by Mr. Bill Lehnman of Weyerhaeuser, Tacoma, Washington (22). 

In the FTM-2 "Formaldehyde Test Method for Large Scale Test Chamber", the method allows a temperature correction factor to be applied to formaldehyde concentrations determined at temperatures other than the desired 25j 0.5 C. In addition, the states of Wisconsin and Minnesota allow temperature corrections of formaldehyde levels determined at temperatures other than 25 C for field complaint investigations. The temperature correction factors are based on the popular Berge Equation (25). 

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.

Formaldehyde concentrations observed in an environmental chamber do relate to real world formaldehyde... 

Colombo A., Jann O. and Marutzky R. (1994) The estimate of the steady state formaldehyde concentration in large chamber tests. Staub Reinh. Luft, 54, 143-146. 

Allow to settle, remove supernatant, and replace with 10 ml fixative. For older egg chambers, use 8% formadehyde in 1 x cacodylate buffer, above, prewarmed to 37 C. For younger egg chambers lower the formaldehyde concentration to 5%. 

Formaldehyde causes eye, upper respiratory tract, and skin irritation and is a skin sensitizer. Although sensory irritation, eg, eye irritation, has been reported at concentrations as low as 0.1 ppm in uncontrolled studies, significant eye/nose/throat irritation does not generally occur until concentrations of 1 ppm, based on controlled human chamber studies. Odor detection has commonly been reported to occur in the range of 0.06—0.5 ppm (133—135). 

Dark Decay of UDMH in Air, UDMH was observed to undergo a gradual dark decay in the 30,000-liter Teflon chamber at a rate which depended on humidity. Specifically, at 41 C and 4% RH the observed UDMH half-life was " 9 hours (initial UDMH 4.4 ppm) and at 40 C and 15% RH, the half-life was -6 hours (initial UDMH 2.5 ppm). The only observed product of the UDMH dark decay was NH3, which accounted for only -5-10% of the UDMH lost. In particular, no nitrosamine, nitramine, or hydrazone were observed. Formaldehyde dimethyIhydrazone was observed in previous studies which employed higher UDMH concentrations and reaction vessels with relatively high surface/volume ratios (, ) ... 

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