Cosalt, a provider of safety equipment to the oil industry, has lost a quarter of its value after the head of its Offshore division was suspended from day to day duties.The company, which makes things like lifejackets, First Aid gear and fire extinguishers, said Calum Melville had also resigned as a director.An internal review of the operating practices of the group's businesses in Aberdeen is underway, a statement confirmed Monday.Melville joined Cosalt when it bought GTC Group, a supplier of lifting equipment to the oil and gas industry he owned with his brother Stuart, in 2008 for £30m.According to its website, Cosalt Offshore has 300 personnel based in Aberdeen and further 110 in Stavanger and Lowestoft providing lifting, tooling and marine services to the oil and gas sector.