Peristaltic infusion pump with locking mechanism

An infusion system comprising:

• a removable mechanical interface unit to support in a fixed position a tube through which a fluid flows;
• a device body with a catch receptacle configured to receive said mechanical interface unit through which the tube passes;
• a peristaltic pump connected to said body and positioned to propel fluid through the tube when the mechanical interface unit is engaged within said receptacle;
• and
• wherein said mechanical interface unit includes an anti-free flow mechanism biased towards a safety default closed state to prevent flow of fluid through the tube when said interface unit is disengaged from said receptacle, and which anti-free flow mechanism is mechanically forced into an opened state by:
• (a) a key structure functionally associated with said receptacle and which applies a force on said anti-free flow mechanism when said interface unit is engaged, and (b) a manual override structure functionally associated with said anti-free flow mechanism is reconfigured it into a default open state.