Ventilated chambers formaldehyde release rate

Table III. Comparison of Formaldehyde Release Rate Coefficients in Ventilated Chambers and Nonventilated Desiccators...

Formaldehyde (CH2O) release was measured for seven types of consumer products pressed wood, urea formaldehyde foam materials, clothes, insulation, paper, fabric, and carpet. A modified Japanese Industrial Standard (JIS) desiccator test was used to measure release rate coefficients and to rank 53 products. Ten pressed wood products and five urea formaldehyde foam products showed the highest CH2O releases (1-34 mg m 2.day"b The remainder, representing all product types, had lower releases ranging from 680 yg m 2.day to nondetectable levels. In other studies, CH2O release was measured in a ventilated chamber for single samples of particle board, plywood, insulation, and carpet. 

In one series of studies, a small static chamber with no ventilation, which was a modification of the Japanese Industrial Standard (JIS) desiccator procedure, was used to compare formaldehyde release from a number of products (1, 7-14). In a second series of studies, a chamber with ventilation rates similar to those in houses was used to more closely mimic actual product use. With this method, combined formaldehyde release from two products placed in the same chamber was compared to their separate releases. 

In dynamic (ventilated) chambers, release rate coefficients were increased by a factor of 4.4 for particle board and 2.2 for plywood at loadings of 1.4-1.6 m /m over values at loadings of 9-11 m2/m3 (Table IV). Increased pressure of formaldehyde in the chamber was associated with reduced release of formaldehyde from wood products, as indicated by comparing equilibrium concentrations of formaldehyde (H). 

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. 

---