Abstract: A print agent vessel is disclosed that comprises a circuit, the circuit comprising a first electrically conductive portion to couple to a first terminal of a printing device, a second electrically conductive portion to couple to a second terminal of the printing device, and an electrically conductive component capacitively coupled to the first electrically conductive portion. The circuit has a variable capacitance that is indicative of a parameter of the component.

Abstract: A print agent vessel is disclosed that comprises a circuit, the circuit comprising a first electrically conductive portion to couple to a first terminal of a printing device, a second electrically conductive portion to couple to a second terminal of the printing device, and an electrically conductive component capacitively coupled to the first electrically conductive portion. The circuit has a variable capacitance that is indicative of a parameter of the component.

Abstract: When a first fluid supply of a fluid-ejection device is empty and a second fluid supply of the device has a non-empty fluid amount less than a threshold, the device performs an action related to the second fluid supply. After the action has been performed and both the first and second fluid supplies have been replaced, the device primes the first and second fluid supplies. The action can include emptying the second fluid supply, and then messaging that both the fluid supplies require replacement. The action can include messaging that both fluid supplies require replacement although the second fluid supply is not empty. The action can include not messaging even that the first fluid supply requires replacement until the second fluid supply also becomes empty.

Abstract: When a first fluid supply of a fluid-ejection device is empty and a second fluid supply of the device has a non-empty fluid amount less than a threshold, the device performs an action related to the second fluid supply. After the action has been performed and both the first and second fluid supplies have been replaced, the device primes the first and second fluid supplies. The action can include emptying the second fluid supply, and then messaging that both the fluid supplies require replacement. The action can include messaging that both fluid supplies require replacement although the second fluid supply is not empty. The action can include not messaging even that the first fluid supply requires replacement until the second fluid supply also becomes empty.

Abstract: In one example in accordance with the present disclosure a fluid storage device is described. The device includes a fluid reservoir to store fluid. The fluid reservoir includes a free fluid chamber and an overflow chamber in fluid communication with the free fluid chamber. The reservoir also includes a seal assembly to, when in a first position, seal a refill port of the free fluid chamber and open an air vent of the overflow chamber. When in a second position, the seal assembly opens the refill port and seals the air vent.

Abstract: In one example in accordance with the present disclosure a fluid storage device is described. The device includes a fluid reservoir to store fluid. The fluid reservoir includes a free fluid chamber and an overflow chamber in fluid communication with the free fluid chamber. The reservoir also includes a seal assembly to, when in a first position, seal a refill port of the free fluid chamber and open an air vent of the overflow chamber. When in a second position, the seal assembly opens the refill port and seals the air vent.