A clamp apparatus is for selectively occluding a resilient tube to prevent free flow of fluid in the tube. The device comprises a base member to which the resilient IV tube is attached or through which it passes, and a slide clamp that slides relative to the base member and relative to the tube. The aperture in the slide clamp has a relatively open hole at one end, through which the tube passes when the slide clamp is an open position, allowing fluid to flow through the tube. The aperture also has a relatively constricted slot at the other end, through which the tube passes when the slide clamp is in the occluding position, preventing fluid flow through the tube. A deflectable cantilevered locking arm on the base interlocks with a detent on a top surface of the slide clamp to lock the slide clamp at the occluding position to avoid inadvertent free flow. A release tab that is used to release the locking arm from the slide clamp is located off centre to avoid inadvertent activation. The slide clamp has a pushing flange capable of receiving a digit of an operator.
