Liquid flow rate control device

A fluid flow rate control device, especially adapted for controlling the flow of IV fluid to a patient, comprises a first vented fluid chamber having an upper fluid inlet end with a hollow spike which enables fluid connection with a conventional fluid container. A free floating float valve in the first chamber blocks the flow of fluid into the first chamber from the fluid container according to whether or not the fluid level in the first chamber is at a preestablished fluid level, thereby providing a constant pressure head regardless of fluid level in the fluid container. A lower end of the first chamber is connected, through a flow regulator, such as a screw-type valve, to an upper inlet end of a second, vented, drip chamber, the lower end of which is adapted for connection to a discharge tube, such as an IV tube. A second, free floating float valve in the second chamber blocks the flow of fluid from the second chamber into the discharge tube when the fluid level in the second chamber is at or below a preestablished minimum level and blocks flow of fluid into the second chamber when the fluid level in the second chamber reaches a preestablished maximum level. A first variation fluid flow control device is disclosed in which the first an second chambers are arranged in a side-by side configuration and a second variation fluid flow control device is disclosed in which fluid flow through the device is controlled in response to relative rotation between axially-aligned upper and lower shell segments of the device.