Modulated pressure control of beer fill flow

A method of filling a beer can having an open top and a widget, the method comprising the steps of:

• providing a beer filling machine comprising:
• a first fill station, the first fill station dimensioned and configured to hold such beer can in place for filling;
• a fill head dimensioned and configured to sit atop such beer can, the fill head in liquid and gas communication with such beer can;
• a beer supply bowl located below the fill head;
• a pressurized gas source;
• a first beer conduit connecting the beer supply bowl to the fill head;
• a second gas conduit connecting the gas source to the fill head;
• a third gas conduit connecting the fill head to the beer supply bowl;
• a fourth snift line connecting the fill head to a purge;
• a first variable progressive valve on the snift line;
• a second variable progressive valve on the second gas conduit;
• and a third variable progressive valve on the third gas conduit;
• a seamer adjacent the first fill station;
• positioning such can in the first fill station;
• sealing the fill head to the top of such beer can;
• in a first pressurization and first purge step, opening the first and second variable progressive valves so that gas flows from the pressurized gas source via the second gas conduit to the fill head and then into such can while allowing air within such can to leave the can via the fourth snift line, thereby pressurizing the can and the widget with gas;
• in a second pressurization and purge step, closing the first and second variable progressive valves and opening the third variable progressive valve so that such can becomes pressurized from the beer supply bowl rather than the gas source and allowing pressure in such can to equalize to pressure in the beer supply bowl and creating counterpressure for later steps of the filing;
• maintaining the counter pressure while supplying liquid from the beer supply bowl to such can via the first beer conduit;
• allowing the liquid to settle in such can whereby gas remaining in such can gathers at the top of such can;
• snifting the can by closing the third progressive variable valve and closing the first beer conduit, but partially opening the first variable progressive valve on the fourth snift line, the partial opening sufficient to allow such can to depressurize down to an ambient air pressure by purging via the fourth snift line but insufficient to cause such widget to depressurize;
• moving such can to a seamer;
• seaming a top onto such can.