Flow controllers

An apparatus for selecting a flow rate of a fluid, the apparatus comprising:

• a holding reservoir comprising an input reservoir port and output reservoir ports, the input reservoir port for introducing the fluid into the holding reservoir, each output reservoir port for dispensing fluid from the holding reservoir;
• an axle comprising an elongated cylindrical member having 2N flow paths, where N is an integer greater than or equal to two, each flow path being defined by a corresponding set of radial holes, each set of radial holes comprising at least one radial hole that extends substantially between an outer surface of the axle and an interior cavity of the axle, at least one of the flow paths being further defined by an axial drain channel that substantially extends longitudinally along a length of the axle;
• a barrel comprising an elongated cylindrical member within which the axle is disposed, the barrel having input barrel ports and an output barrel port, the barrel being configured to enable the axle to rotate about an axis of rotation that extends along the length of the axle;
• N fluid-carrying channels, each fluid-carrying channel being coupled to a respective one of the output reservoir ports and a respective one of the input barrel ports;
• and
• a housing having a chamber within which the holding reservoir, the axle, the barrel, and the fluid-carrying channels are disposed;
• wherein a flow rate of a fluid is selected by rotating the axle to a position so that a set of radial holes is in alignment with one or more ports of the barrel and the holding reservoir is in fluid communication with the interior cavity of the axle via one or more fluid-carrying channels,
• wherein a length of the axial drain channel along a longitudinal axis of the axle is larger than a width of the axial drain channel along a radial axis of the axle.