Shares of environmental technology firm Porvair rose after it confirmed that it had made a good start to the year and expects to report interim profits well ahead of last year.The Norfolk based company, which makes fuel and coolant filters for commercial aircraft such as the Airbus and Boeing models, said several major contracts announced earlier in the year will boost the group's performance over the next few years. It said all are on schedule and have started to contribute to results. Provair also announced that its Microfiltration division has acquired Caribou, Maine based Chand Eisenmann Metallurgical (CEM) for $5.5m in cash and loans."There is a good commercial fit between CEM and Porvair's existing product portfolio. With clear cross-selling opportunities, the combined business is well positioned to accelerate its rate of growth in the US. The transaction is expected to be immediately earnings accretive," Porvair said. Otherwise, in an update ahead of its interim results in June, Provair said group revenue is expected to be around 7% ahead of the first six months of 2012 at constant currency rates. Order books are strong in Microfiltration and market share gains continue to be made in Metals Filtration.Commenting on its acquisition, Chief Executive Ben Stocks commented: "CEM is a highly complementary bolt-on acquisition which broadens our product range, geographic spread and materials expertise. There are many cross-selling opportunities apparent in this transaction and we plan to invest in the Caribou facility over the next 12 months to accommodate the expected growth." He added: "Trading in the first half of 2013 has been satisfactory, and the prospects for the second half; supported by our order books, recent large engineering contracts, and the CEM acquisition; are good."Shares in Porvair rose 3.26% to 269.50p at 09:40 in London.CJ