then be changed using the other hand release of the pressure applied to the lever 170 will cause it to return to a position engaging the inner grooves 164 on the dial and again locking the dial in the set position in the operation of the flow regulator a roller or slide clamp if used is placed in a closed position and the flow regulator is placed in the tubing line at a convenient location between the drip chamber and the administration needle as seen in fig1 the flow regulator needs to be positioned below the fluid level of the container as the device is gravity driven conventional connectors and adaptors are conventionally used and are employed to make the connection air is purged from the system by opening the flow regulator to the full open or purge position as indicated by the indicia on the control dial 140 and disengaging the roller clamp slide clamp once the air is purged from the system the control knob is rotated to a position to a fully closed position by turning on the knob to force the disk downwardly once a needle is inserted in the venipuncture site u201c v u201d the control dial can be rotated to the suitable selected position indicated on the dial to establish a desired flow rate in some instances it may be desirable to check or confirm the flow rate by timing the drop rate through the drip chamber the medical clinician will confirm the flow rate by timing the drop rate through the drip chamber once the device is set at the desired flow rate the control membrane 80 will function and maintain an essentially constant flow rate regardless of changes in fluid level within.