An electropneumatic proportional flow control device improves electropneumatic control of pneumatically operated valves. Improved turn down ratios in regards to the electromagnetic response of the device to a supplied control voltage is achieved using two variable spring devices, one linear, as part of the pressure regulator valve component, and the other non-linear, as part of the proportional valve component and which are magnetically responsive to different magnetic forces. The use of both the linear and non-linear springs together results in an increased turndown-ratio, especially during initial valve control.