Extraction reservoir-triggered fluid extraction

A fluid transport system comprising:

• a reservoir to hold an amount of fluid;
• an interface to fluidically couple a removable extraction reservoir to a printing device;
• a supply line to connect the interface and the reservoir;
• a fill pump to draw fluid to the reservoir;
• a return line to connect the reservoir and the supply line, wherein the return line is coupled to the supply line between the interface and fill pump;
• a return line valve disposed along the return line to open and close the return line;
• a switch disposed in the interface to:
• responsive to attachment of the removable extraction reservoir to the printing device, open the return line valve to direct fluid from the reservoir to the removable extraction reservoir;
• and
• responsive to removal of the removable extraction reservoir from the printing device, close the return line valve;
• and
• a recirculation pump to, during an extraction operation, move fluid from the reservoir to the interface.

A method comprising:

• receiving, at an interface of a printing device, a removable extraction reservoir;
• responsive to attachment of the removable extraction reservoir, opening a return line valve to fluidically couple a return line to the removable extraction reservoir;
• and
• extracting fluid from the reservoir to the removable extraction reservoir.