Shares in specialist filtration firm Porvair stormed ahead after it said full year results are expected to be well ahead of expectations. The group, which provides equipment for the aviation and energy sectors, said revenue in aviation started to recover in the third quarter and aviation order intake during the quarter has been stronger.In the nine months to August Porvair said revenues were more than 10% higher than the prior period and profit before tax is well ahead of the prior year. Metals filtration sales were up 20% while Microfiltration sales revenues are 10% ahead of the prior period."Strong cash flows have reduced net borrowings significantly below the same time last year," the group said in a company statement.