THEORY OF OPERATION OF THE POSIFILLER
It is important to note that the Posifiller is an enclosed system. No air is allowed into the system from the surge tank, through the Posifiller premeasuring cylinder or through the fill nozzles.
Fluid product is introduced into a pressurized surge tank and is then distrubuted through a centralized product manifold to the Posifiller cylinders. A free-floating piston, driven by the product, travels between two positive stops. The lower stop is the bottom cylinder block, the upper stop is the adjustable volume rod, which determines the stroke of the piston inside the cylinder. This stroke of the piston determines the volume of the fill.
The key is having pressurized product on both sides of the piston at all times. To achieve this, a unique for-way spool valve is used. When there is no bottle present, the fill nozzle is closed and sealed. There is equalized product pressure on both sides of the piston placing the system in neutral. When a nozzle is cammed open by a container, pressure is relieved on the side of the piston. High-pressure product forces the piston in one direction while the low-pressure product is dispensed through the spool valve and nozzle into the bottle.
The system is designed so that the piston completes one up and one down cycle to exactly fill each bottle. Once the piston has traveled its full stroke in one direction, the spool valve is mechanically shifted reversing the product flow causing the piston to be pushed in the opposite direction. The second half of the total volume is displaced into the bottle which is now full. The piston is at its original position and the fill nozzle is closed.
The volume rod which limits the stroke of the piston is indivivually adjustable on each Posifiller premeasuring cylinder, enabline fine tuning to achieve the +/- 1/4 of 1% accuracy. The rods are attached to a motorized volume plate, operated by push-button on the control panel, which adjusts fill volumes on all stations at once.
Laub\Hunt Packaging Systems, 13547 Excelsior Drive, Norwalk, CA 90650-5236. Tel: 562-802-9591; Fax: 562-802-8183.