Vessel and methods for calibrating, cleaning or removing an implement located in such a vessel or inserting an implement into such a vessel

A vessel having an implement located in a fluid receiving space inside the vessel. The vessel includes an enclosure for enclosing a closed space around the implement. An actuator actuates the enclosure to and fro between an open position, in which the enclosure does not enclose a closed space around the implement, and a closed position, in which the enclosure forms a fluid tight or at least essentially fluid tight casing that encloses a closed space around the implement so as to prevent fluid in the fluid receiving space outside the closed space from flowing into the closed space. A method for cleaning and/or calibrating an implement located in a fluid receiving space inside such a vessel and a method for removing an implement from or inserting an implement into a fluid receiving space inside a vessel.