A channel device is disclosed for transporting gas and/or liquid between a control unit and a scope accessory, the channel device comprising a wash line, the wash line comprising: a wash line gas channel； a wash container； a piston； and a wash line wash channel, the wash line gas channel being configured to receive a gas from a wash line gas output of the control unit, the piston being configured to be actuated due to an increase in pressure in the wash line gas channel caused by the received gas to cause a liquid to be expelled from the wash container, the wash line wash channel being configured to transport the expelled liquid to the scope accessory.
