Peristaltic pump apparatus having an improved misloaded IV tube detecting circuit

A peristaltic pumping apparatus comprising:

• a body having a wall portion and a door for allowing access to said wall portion in its open position and impeding access to said wall portion in its closed position;
• a propelling means provided at said wall portion for propelling a fluid contained in a tube placed on said propelling means with a peristaltic pumping action when said door is closed;
• a detecting means for detecting misloading of said tube, said detecting means having:
• (a) a sensing means provided in the vicinity of said propelling means for sensing a pressure applied to said sensing means, and including a variable resistive element whose resistance varies in accordance with a magnitude of the applied pressure and a resistor connected in parallel with said variable resistive element and having a resistance of a predetermined value;
• (b) a comparing means for receiving output from said sensing means and comparing a resistance of said sensing means with the resistance of said resistor and with a specified value which is smaller than the resistance of said resistor;
• and
• (c) a judging means for making a decision based on comparison results as to whether said tube is properly loaded or misloaded or whether said sensing means is in an inoperative state such as a damaged or unpowered state.