Fluid extraction using fill pump activation

1. A fluid extraction system comprising:

an interface to fluidically and electrically couple a removable extraction reservoir to a printing device;

a supply line to transport fluid from the interface to a reservoir of the printing device;

a return line coupled to the reservoir and the supply line to transport fluid from the reservoir to the interface; and

a switch to, responsive to removal of the removable extraction reservoir from the printing device, activate a fill pump to draw fluid through the supply line away from the interface.

2. The fluid extraction system of claim 1 , wherein the fill pump is to draw fluid through the supply line to the reservoir.

3. The fluid extraction system of claim 1 , wherein the switch is to send a signal to a controller to activate the fill pump.

4. The fluid extraction system of claim 3 , wherein the controller is to deactivate the fill pump a predetermined amount of time following removal of the removable extraction reservoir.

5. The fluid extraction system of claim 1 , wherein the switch is to directly control the fill pump.

6. The fluid extraction system of claim 1 , wherein the switch:

responsive to attachment of the removable extraction reservoir to the printing device, is to open the return line to direct fluid from the reservoir to the interface; and

responsive to removal of the removable extraction reservoir from the printing device, is to close the return line.

7. The fluid extraction system of claim 6 , wherein opening the return line comprises:

activating a recirculation pump to draw fluid through the return line; and

opening a return line valve.

8. The fluid extraction system of claim 6 , wherein closing the return line comprises:

deactivating the recirculation pump; and

closing the return line valve.

9. 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 to the supply line between the interface and the fill pump, and to transport fluid from the reservoir to the interface;

a return line valve disposed along the return line to open and close the return line;

a switch to, responsive to removal of the removable extraction reservoir from the printing device, activate the fill pump to draw fluid through the supply line away from the interface; and

a recirculation pump to, during an extraction operation, move fluid from the reservoir to the interface.

10. The fluid transport system of claim 9 , further comprising:

a fluid level sensor disposed in the reservoir;

a vent assembly disposed on the reservoir;

a pressure control device disposed along a printhead return line;

or a combination thereof.

11. The fluid transport system of claim 9 , wherein the return line is in fluid communication with a printhead line that delivers fluid to a printhead.

12. A method comprising:

receiving, at an interface of a printing device, a removable extraction reservoir;

extracting fluid from the reservoir to the removable extraction reservoir; and

responsive to removal of the removable extraction reservoir, activating a fill pump to draw fluid through the supply line away from the removable extraction reservoir.

13. The method of claim 12 , further comprising, deactivating the fill pump following a predetermined period of time following removal of the removable extraction reservoir.

14. The method of claim 12 , further comprising, responsive to removal of the removable extraction reservoir, closing a return line valve.

15. The method of claim 12 , further comprising, responsive to removal of the removable extraction reservoir, deactivating a recirculation pump.