Abstract: A control device and system for controlling the opening of a loading and unloading door of a dry washing machine when internal thereof the machine reaches a predetermined maximum gas concentration including a probe having two electrodes spaced from each other for measuring ohmic resistance of air interposed therebetween the ohmic resistance being changeable and responsive to a concentration of the gas contained within the washing machine, the probe measures the solvent concentration degree which is present at the time of measurement in the machine, the probe is coupled with an electronic circuit for controlling the air circulation in the washing machine, and the probe is responsive to a value prefixed and when the value is reached, the probe activates the electronic circuit for breaking the circuit and cuts off air circulation inside the washing machine, and another electronic circuit is coupled with the one electronic circuit for controlling an electrovalve which drives a linear variator with a pneumatic pis