Strong sales of gas masks and a recovery in the dairy industry are set to inflate profits at Avon Rubber.Avon said first half commercial sales of masks and protective breathing equipment to fire services and industry were strong, helping it to reduce reliance on US Department of Defense (DoD) contracts amid budget cuts.The group said second half sales were weighted towards lower-margin DoD work, meaning first half results were likely to contribute more to full year results.Avon, which also supplies milking equipment to farmers, said markets had returned to historical buying patterns for its consumable products because animal feed prices had returned to more normal levels."As a result of strong trading, we expect the half year result to be substantially better than in 2013," Avon said in a trading update ahead of its first half results on Wednesday April 30th.It added that full-year adjusted operating profit was likely to be towards the upper end of current market expectations of £14.8m-£15.5m.Shares in Avon rose 14p or 2.3% to 624p by 12:05 in London.PW