14 will stay on until the vacuum level sensed by vacuum detector 30 exceeds a predetermined level step 108 or a maximum load time step 110 is exceeded once the maximum load time is exceeded step 110 or the vacuum level exceeds the maximum predetermined level step 108 vacuum activated control 32 will turn off vacuum source 14 step 112 after the vacuum source 14 is turned off step 112 vacuum activated control 32 causes a time delay step 116 to allow the material in the hopper 12 to discharge and then the vacuum activated control 32 returns to step 102 the typical time delay used in the control to empty hopper 12 is 5 seconds this time is to ensure that the vacuum source 14 has completely stopped and given gravity a chance to pull valve plate 22 open however if the bin not shown below hopper loader 10 a is full it may actually take several minutes or longer for hopper 12 to become empty this differs from existing technology as it is independent of time and does not rely on sensing the presence of material this results in a system that will adapt as variations in external parameters take place without the intervention of an operator this system also does not suffer problems associated with sensing the material such as u201c false full u201d signals created by material clinging to the sensor due to static electricity sensor circuitry drift causing the sensor to no longer operate properly sensor adjustments necessary due to variations in the material being sensed abrasion of sensors in direct contact with material.