Hewlett-packard Development Company, L.p.

Russell Sterling Sauer

Christopher John Arnold

Wesley R Schalk

Kenneth R Williams

Melissa S Gedraitis

An example of an apparatus is provided. The apparatus includes a current source. The apparatus includes a conductor in electrical communication with the current source and a conductive fluid in a reservoir. The apparatus includes a first sensing rod to extend into the reservoir, wherein the first sensing rod has a first diameter. The apparatus includes a tip disposed at an end of the first sensing rod to interact with a surface of the conductive fluid. The tip has a second diameter over a first portion of the tip adjacent to the first sensing rod. The second diameter is smaller than the first diameter. The apparatus includes a sensor to detect an electrical signal between the conductor and the first sensing rod.

Sensing rods with tips for fluid detection

A fluid delivery system may include a fluid reservoir that may include a fluid supply port through which fluid is supplied to the fluid reservoir, a fluid outlet port through which a first portion of discharged fluid is supplied from the reservoir to a fluid ejection device, a fluid inlet port through which a second portion of the discharged fluid is recirculated back to the reservoir and through which air is pushed into the reservoir and an atmospheric vent to vent the air, that was pushed into the reservoir through the fluid inlet port, from the reservoir.

Fluid delivery

An extraction pump of a printing device fluidically connected to a reservoir of the printing device is set to a specified rotational velocity. A pulse-width modulation (PWM) value of the extraction pump correspondingly increases until the extraction pump rotates at the specified rotational velocity. While the power of the extraction pump is monitored, a power of a supply pump of the printing device fluidically connected between the extraction pump and the reservoir is continually increased; the power of the extraction pump correspondingly decreases to maintain rotation of the extraction pump at the specified rotational velocity. Responsive to the power of the extraction pump decreasing to a characterized value for the specified rotational velocity, the power of the supply pump ceases being increased.

Fluid recirculation within printing device reservoir via extraction pump and supply pump

In example implementations, a storage apparatus is provided. The storage apparatus includes a sealed reservoir partially filled with a print agent. A float is partially submerged in the print agent. A weight is coupled to a submerged portion of the float. A vent is coupled to the float and an opening in the sealed reservoir. A valve is coupled to an unsubmerged portion of the float.

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Vancouver, WA, United States of America

Russell Sterling Sauer