Short tube
The short tube valve has a bottle sealing gasket which grips a slider on the tube. As the bottle is lifted up to the filling valve, the upward motion of the slider starts the liquid flow. At the end of the filling cycle, accurate fill levels are assured using a "liquid leveling by over pressure" feature.
Oxygen protection of the product during filling is, typically, accomplished by using a separate machine in front of the filler to sparge the bottle with inert gas prior to the bottle entering the filler.
Long tube
A long tube filler has a tube that goes down to the bottom of the bottle. There are several advantages to this technology of filling.
Inherently low oxygen pick up. Only about 10% of a short tube filling system.
Low agitation of the product so foaming is reduced.
Higher flow rates so filling is faster and the number of valves required for a given speed is lowered.
There is an additional feature on the SMB Technik long tube valve not found on other fillers.
Inert gas can flow through the long tube prior to filling.
So oxygen protection is achieved not only from the inherent advantages of a long tube, but also by sparging the bottle through the tube to remove air before filling begins.
This system does not require a separate machine in front of the filler to sparge the bottles with inert gas.