DISTRICT board chairmen were treated to a demonstration of fire-fighting techniques yesterday in the first of a planned series of tours designed to improve their understanding of the operations of Government departments. Eleven chairmen accompanied by City and New Territories Administration officials, including the acting secretary for home affairs, Mr Albert Lam Chi-chiu, inspected the control room at the Fire Services Department in Tsim Sha Tsui before watching practical demonstrations. Mr Lam was pleased the Fire Services Department had invited the boards' chairmen to visit and said it gave them a better understanding of the service. ''This is part of a series of visits which Government departments are undertaking to invite district board chairmen to come along to see them at work and see how they operate,'' he said. ''I believe this will be conducive to a better understanding by district board members of Government activities and programmes.'' Mr Lam said he was impressed by the control room and its $100 million computer as well as by the professionalism of fire officers.