A flow selector for selectively controlling a flow rate of a fluid, the flow selector comprising: an inlet tube; an outlet tube; a flow rate selection mechanism, the flow rate selection mechanism including a shaft having a distal end and a proximal end, the shaft comprising indicia for indicating a selected flow rate to a user of the flow selector, and a seat that receives the distal end of the shaft, the seat comprising a recess, wherein the flow rate selection mechanism is positioned between the inlet tube and the outlet tube to permit an ingress of fluid from the inlet tube into the recess and an egress of fluid from the recess to the outlet tube, wherein the shaft moves axally into and out of the recess of the seat to control the flow rate of the fluid to the outlet tube to the selected flow rate by adjusting an available volume (V A) of the recess; and an enclosure for holding the inlet tube, the outlet tube, and the flow rate selection mechanism in position relative to each other, the enclosure having an inlet opening for receiving the inlet tube, an outlet opening for receiving the outlet tube, and a shaft opening for receiving the shaft of the flow rate selection mechanism, wherein the indicia are arranged along the shaft such that the indicia move into and out of the enclosure as the shaft moves axially within the recess of the seat and a portion of the shaft visible to the user indicates the selected flow rate. an inlet tube; an outlet tube; a flow rate selection mechanism, the flow rate selection mechanism including a shaft having a distal end and a proximal end, the shaft comprising indicia for indicating a selected flow rate to a user of the flow selector, and a seat that receives the distal end of the shaft, the seat comprising a recess, wherein the flow rate selection mechanism is positioned between the inlet tube and the outlet tube to permit an ingress of fluid from the inlet tube into the recess and an egress of fluid from the recess to the outlet tube, wherein the shaft moves axally into and out of the recess of the seat to control the flow rate of the fluid to the outlet tube to the selected flow rate by adjusting an available volume (V A) of the recess; and a shaft having a distal end and a proximal end, the shaft comprising indicia for indicating a selected flow rate to a user of the flow selector, and a seat that receives the distal end of the shaft, the seat comprising a recess, wherein the flow rate selection mechanism is positioned between the inlet tube and the outlet tube to permit an ingress of fluid from the inlet tube into the recess and an egress of fluid from the recess to the outlet tube, wherein the shaft moves axally into and out of the recess of the seat to control the flow rate of the fluid to the outlet tube to the selected flow rate by adjusting an available volume (V A) of the recess; and an enclosure for holding the inlet tube, the outlet tube, and the flow rate selection mechanism in position relative to each other, the enclosure having an inlet opening for receiving the inlet tube, an outlet opening for receiving the outlet tube, and a shaft opening for receiving the shaft of the flow rate selection mechanism, wherein the indicia are arranged along the shaft such that the indicia move into and out of the enclosure as the shaft moves axially within the recess of the seat and a portion of the shaft visible to the user indicates the selected flow rate. an inlet opening for receiving the inlet tube, an outlet opening for receiving the outlet tube, and a shaft opening for receiving the shaft of the flow rate selection mechanism, wherein the indicia are arranged along the shaft such that the indicia move into and out of the enclosure as the shaft moves axially within the recess of the seat and a portion of the shaft visible to the user indicates the selected flow rate.