A fluid delivery device such as a cassette removably disposed in a medical pump to control fluid flow in the medical pump. The fluid delivery device has an elongated main body including an inlet, an outlet, and a fluid passage extending from the inlet to the outlet. A flow stop is pivotally mounted to the main body for selectively allowing and stopping fluid flow from the fluid passage to the outlet. The fluid delivery device can have various features including the flow stop having grooved sections, a T-shaped collar on the main body inlet or a flange on the main body to prevent inadvertent engagement of the flow stop during removal of the fluid delivery device from the medical pump.