Assessment of the Atmosphere Composition after Washing, Gas-Freeing and Aerating Processes in Vessel Cargo Tanks

Paper discussed the problem of proper process of gas-freeing and ventilation of vessel cargo tank after washing process in aim to the entrance into the tank and its inspection. Correct assessment of atmosphere composition into the cargo tank is a basic condition of safe entrance and work of a crew. It should be done following actions: assessment of flammability hazard, the presence of other toxic gases for human and oxygen concentration. In the aim ship-owner should prepare adequate procedures: before entrance, during work and on emergency situations. On a vessel the assessment performs responsibility (entitled) officer whose decisions are crucial for the safety of prosecuting operations. The one of primary problem is proper (adequate) assessment of oxygen concentration in the air into the tank (enclosed spaces) after the measurement which should be properly interpreted. It concerns basically such situations when the oxygen concentration into the tank after measure leads the value over 22% or below 20.6% of volume (mole) contribution (v/v).