Method for detection of fluid flow

A spray gun system comprising:

• a spray gun configured to distribute a mixture of air and fluid onto a working surface;
• a pressure sensor fluidly connected to the spray gun, wherein the pressure sensor is configured to measure fluid pressure within the spray gun system;
• and
• a controller electrically connected to the pressure sensor, wherein the controller is configured to:
• receive a measured pressure from the pressure sensor;
• calculate pressure error based on the measured pressure and a pressure set-point;
• compare the pressure error to an error threshold;
• increment an increment counter if the pressure error exceeds the error threshold;
• determining that fluid is flowing through the spray gun based on the increment counter exceeding a count threshold;
• perform, in response to determining that fluid is flowing through the spray gun based on the increment counter exceeding the count threshold, a flow control loop that adjusts the pressure set-point to achieve a target flow rate;
• and
• perform a pressure control loop to adjust the fluid pressure within the spray gun system to achieve the pressure set-point.