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ASTM E1333 - Large Chamber Formaldehyde Testing

ASTM E1333 - Standard Test Method for Determining Formaldehyde Concentrations in Air and Emissions Rates from Wood Products Using a Large Chamber

ASTM E1333 is the primary method for testing products for formaldehyde off-gassing. This test method is used to measure the formaldehyde concentration in air and emission rate from wood products containing formaldehyde under conditions designed to simulate product use. It uses a large, room-size chamber where the product being tested is placed inside and allowed to off-gas in dynamic conditions for a specified length of time before the chamber air is sampled and analyzed for its formaldehyde concentration. The analytical method typically used is an adaptation of the NIOSH (National Institute for Occupational Safety and Health) 3500 chromotropic acid test procedure.

Specimens

The standard can test a wide variety of wood products. Typically the specimens are newly manufactured 4-ft by 8-ft sheets of composite wood products; however, testing of complete, assembled finished goods containing composite wood products is also allowed. When testing previously installed or used products, the method of packaging and shipping the product for testing needs to be considered and documented in the test report.

Critical Test Parameters

Critical parameters of the test procedure are the loading ratio, air exchange rate, temperature, and humidity; each is defined below.

Loading Ratio is the total exposed surface area of each panel product divided by the test chamber volume. The edge area is excluded from the exposed surface area unless the exposure constitutes more than 5% of the overall surface area. The formaldehyde concentration in air is directly related to a change in the loading ratio. The standard allows non-standard configurations such as panels back-to-back, complete assemblies, and combination test (multiple product types tested at the same time).

Air Exchange Rate is the ratio of hourly conditioned and filtered outside air brought into the chamber to the chamber volume measured in identical volume units. This make-up air is passed through a filter bed of material capable of absorbing, adsorbing, or oxidizing formaldehyde such as activated carbon and activated alumina impregnated with potassium permanganate. The formaldehyde concentration in air is inversely related to a change in the exchange rate.

Temperature of the air in the chamber has a direct effect on the amount of formaldehyde off-gassing a product will exhibit. A deviation of as little as 0.5 ºF from the standard temperature requires a correction on the formaldehyde concentration in air. The relationship between temperature and concentration is representation in the graph below.
Chart 1

Humidity of the air in the chamber has an even greater direct effect on the amount of formaldehyde off-gassing a product will exhibit. A deviation as little as 1 %RH from the standard relative humidity requires a correction on the formaldehyde concentration in air. The relationship between humidity and concentration is representation in the graph below.
Chart 2
Since these test parameters can dramatically affect the test results, the concentration in air and emission rate are only relevant to the specific parameters used. Concentrations in air and emission rates do not change proportionally with changes in air exchange rates or loading ratios. Estimates of formaldehyde exposure in structures can only made by using mathematical models obtained in extending the parameters of the standard to multiple chamber air exchange rates or multiple product loading ratios, or both.

Standard test conditions are 77 ºF and 50 %RH, 0.5 air exchanges per hour, and loading ratios of 0.29-ft2/ft3 for hardwood plywood wall panels, 0.13-ft2/ft3 for particleboard and industrial panels, and 0.08-ft2/ft3 for Medium-density fiberboard.

 

Reporting

A test report or summary for all materials tested to ASTM E1333 should contain a minimum of the following:

  1. A unique identifying test number
  2. Date of the test
  3. Product Manufacturer/Company
  4. Description of the material or product, including name, thickness, size, and surface finish
  5. Manner of shipment and/or storage
  6. Testing configuration
  7. Any material machining
  8. Conditioning details, including temperature and humidity ranges, time, and spacing
  9. Background formaldehyde concentration during conditioning
  10. Test chamber volume
  11. Test material loading ratio
  12. Description of specimens as loaded into test chamber
  13. Background formaldehyde concentration of the air in the test chamber prior to test
  14. Average and range of temperature and humidity during conductance of the test and the test chamber sampling and an indication if corrections to the formaldehyde concentration in air are required
  15. Average air-exchange rate during test
  16. Air sampling rate and time
  17. Test chamber formaldehyde concentration in air at test conditions and corrected to standard conditions and the formaldehyde emission rate at standard conditions

 

NTA Inc. ASTM Testing
NTA Inc. fire testing services are conducted in a state-of-the-art testing laboratory overseen by registered professionals. Our fire safety testing services help manufacturers in the recreational vehicle and manufactured housing industries ensure compliance with these rigorous standards, and ensure that your products are safe and ready for consumers. Timely service is always accompanied by detailed reports that provide precise documentation in an easy-to-read format. Call us today at 1-574-773-7975 for more information about our certified fire testing program.