PHOTO: TWIN PORTS TESTING
quality
It has taken nearly three years to design a comprehensive set of 29 standards and tests to determine the quality of fuel pellets.
50 BIOMASS MAGAZINE 7|2008
fireplaces. The need for standards that reflected the different markets for pellet fuels became the premise for framing the new standards. “A stove is a lot more finicky,” Wiberg says. “It has to have [pellets of] a very consistent density and diameter. So we had to ask, ‘What should a good, high-quality, high-efficiency stove be burning?” After three years of work, the Pellet Fuels Institute is close to releasing its revised quality standards. The new standards will recognize four grades of pellets: super premium, premium, standard and utility. “Each grade has a specific battery of specifications, both physical and chemical,” Wiberg says. The other part of the specifications is the recognized testing methods for each of the quality parameters. “We did an extensive research project on what methods are out there and who is using what method,” Wiberg says. “It wasn’t just the European Union. Germany had its own standards as did Austria, Sweden and Britain. There are about a dozen countries that have something going on with pellets. Everybody is kind of doing their own thing.” ASTM International has no standard for fuel pellets, but the Pellet Fuels Institute specifications will follow the ASTM format. If the industry approves the rules, they will be presented to ASTM for consideration as a new standard. Most of the test methods used in the institute’s standards are based on recognized ASTM methods. A few of the methods did have to be modified to cope with the unique property of fuel pellets. Wiberg describes the bulk density test, which in the ASTM standard required a cubic-foot container of pellets to be dropped 6 inches three times. Because pellets are a loose product, dropping a container from 6 inches will cause a significant number of the pellets to fly up and out of the box. So a method using a quarter-cubic-foot box that was tapped from about an inch high was adapted. The group then had to determine how many taps were needed to get a similar result to the ASTM standard. “We probably ran 100 density tests to tell us we were going to tap it 25 times.