Section 39.4003 - Design and equipment for vapor balancing-TB/ALL(a) During transfer operations, if the cargo tanks are inerted on a vessel discharging cargo to a receiving vessel with inerted cargo tanks, the service vessel must- (1) Inert the vapor transfer hose prior to transferring cargo vapor; and(2) Have an oxygen analyzer with a sensor or sampling connection fitted within 3 meters (9.74 feet) of the vessel vapor connection that- (i) Activates a visible and an audible alarm on the service vessel where cargo transfer is controlled when the oxygen content in the vapor collection system exceeds 60 percent by volume of the cargo's minimum oxygen concentration for combustion (MOCC), or 8 percent by volume for vapor of crude oil, gasoline blends, or benzene;(ii) Has an oxygen concentration indicator located on the service vessel where the cargo transfer is controlled; and(iii) Has a connection for injecting a span gas of known concentration for calibration and testing of the oxygen analyzer.(b) If the cargo tanks are not inerted on a vessel discharging cargo during transfer operations, and the cargo is flammable or combustible, the vapor collection line on the service vessel must be fitted with a detonation arrester that meets the requirements of 33 CFR 154.2106 , and be located within 3 meters (9.74 feet) of the vessel vapor connection.(c) An electrical insulating flange or one length of non-conductive hose must be provided between the vessel vapor connection on each vessel operating a vessel-to-vessel cargo transfer.