Abstract: Fitting in connecting pipes to air space of tanks on the tank farm with oil coming and going constantly is able to eleminate big breathing losses and reduce the small ones for the most part. Take the initial station of Kelamayi-Dushanzi pipeline for example, 1263.63 tons of oil products are saved annually, with an extral profit of 127.050 thousand yuans This device, with a little investment and better effect, can be widely applied to oil collecting stations, tank farms, and the initial and terminal stations of oil pipelines with more than two oil tanks where oil is kept running up and down.