Mechanical valve and breathing machine

The mechanical valve comprises a valve element, an adjusting knob, a potentiometer and a control piece, the valve element is used for being installed at a gas path channel of a gas path module, one end of the valve element can close or open the gas path channel, one end of the adjusting knob is connected with the other end of the valve element, and the potentiometer is connected with the control piece. The adjusting knob is arranged on the valve element to drive one end of the valve element to close or open the gas path channel through rotation, the potentiometer is connected with the adjusting knob and used for detecting the rotation angle of the adjusting knob, and the control piece is electrically connected with the potentiometer to receive signals transmitted by the potentiometer and convert the signals into equipment corresponding parameters. According to the technical scheme, the mechanical valve can achieve the effects that the ventilation capacity of the gas circuit module can be mechanically adjusted