If you are looking to store your Conway Stewart pens for a long period of time without use. Be sure to drain them: hold the pen over a sink and turn the euro-converter knob anti-clockwise to purge the ink.
Then dip the nib into a glass of lukewarm water and turn the knob clockwise to fill the converter with water, and then hold the pen above the water and turn the knob anti-clockwise to purge the converter of water. Do this several times to clean the nib and converter.
Then dry the nib with a tissue, and let it dry in the air (couple of hours) before screwing the cap back on. Then when you want to re-use the pen, simply fill with ink in the normal way. (If ink is left in the pen for several months (ie 6 months +) without using it, the ink can evaporate and leave a sediment that can hinder the ink flow.