Control arrangement and method for controlling a sensorless membrane pump

A control arrangement for controlling a sensor-free diaphragm pump, the control arrangement comprising:

• a control-fluid inlet for connection to a first control-fluid reservoir having a pressure level which is elevated in relation to a reference pressure;
• a control-fluid outlet for connection to a second control-fluid reservoir having a pressure level which is reduced in relation to a reference pressure;
• a control-fluid connection for connection to a control-fluid line for the sensor-free diaphragm pump, wherein the control-fluid inlet is connected via a first proportional valve to a collecting point, and the control-fluid outlet is connected via a second proportional valve to the collecting point, and wherein a mass flow sensor is arranged between the collecting point and the control-fluid connection;
• and
• a control unit in signal communication with the first proportional valve, the second proportional valve, and the mass flow sensor, wherein the control unit is configured to control a control fluid flow based on data detected by the mass flow sensor, wherein for controlling the control fluid flow based on the data detected by the mass flow sensor the control unit is adapted to actuate the first proportional valve of the control arrangement for enabling throughflow, and conveying a first volume of a control fluid, close the first proportional valve when the first volume of a control fluid to be conveyed has been reached, actuate the second proportional valve for enabling throughflow, and conveying a second volume of a control fluid, and close the second proportional valve when the second volume of a control fluid to be conveyed has been reached,
• wherein the control unit is further configured to determine the volumes to be conveyed of the control fluid, wherein determining the volumes to be conveyed comprises:
• detecting a mass flow rate of the control fluid based on the data detected by the mass flow sensor,
• deducing a volumetric flow rate from the mass flow rate, and
• deducing a volume of the conveyed control fluid from the volumetric flow rate.