I am currently looking to seal an outlet, for which we have 7 different sizes (see "outlet dims" for dimensions). Product passing through the outlet can vary, with anything from metal powders to food or pharmaceutical product being used. The idea is to have an inflatable seal or bladder, where on inflation, the seal is watertight. Deflation may be achieved using a venturi valve (or vacuum ejector) to create suction required to deflate the seal/bladder, retracting to allow for at least half the outlet to be open (allowing substantial product to flow through the outlet).
A perimeter (standard section) extruded inflatable seal was initially looked at, but this was dismissed as the deflation/inflation required to seal the outlet when expanded and open half the outlet when deflated was not easily achieved. As a result, a natural rubber (1-2mm thickness) natural rubber bladder was used, with an outer plastic channel to constrain the bladder on inflation and an inner channel to keep the sides apart on deflation (as shown in the pictures).
There aren't a great deal of constraints to the design or specification of the bladder. However, all materials used should be FDA approved, so materials such as natural rubber or EPDM would be strong candidates for selection. With the inflatable bladder that was used, one concern might be long-term deformation of the material. This is where something like an extruded, thick walled, inflatable seal may be better. There is potential for modifying the outlets, as has been done with increasing the edge radius's to 20mm to allow for better edge sealing.
Does anyone have any ideas as to how the sealing of the 7 different outlet sizes can be achieved? For example, a bladder could be blow moulded, with the tooling being modified using inserts to obtain variable size of bladder with the same tooling. Does anyone know of any extruded seals that may be able to achieve the required inflation and deflation? Would fabricating two extruded seals together (with one valve) be a feasible option for achieving the inflation required? Any suggestions or guidance would be useful, regarding the design, possible manufacturing processes and potential suppliers that you may recommend (considering that I am based in the west London/Heathrow airport area – although I am open to suggestions of suppliers anywhere in the world).
A perimeter (standard section) extruded inflatable seal was initially looked at, but this was dismissed as the deflation/inflation required to seal the outlet when expanded and open half the outlet when deflated was not easily achieved. As a result, a natural rubber (1-2mm thickness) natural rubber bladder was used, with an outer plastic channel to constrain the bladder on inflation and an inner channel to keep the sides apart on deflation (as shown in the pictures).
There aren't a great deal of constraints to the design or specification of the bladder. However, all materials used should be FDA approved, so materials such as natural rubber or EPDM would be strong candidates for selection. With the inflatable bladder that was used, one concern might be long-term deformation of the material. This is where something like an extruded, thick walled, inflatable seal may be better. There is potential for modifying the outlets, as has been done with increasing the edge radius's to 20mm to allow for better edge sealing.
Does anyone have any ideas as to how the sealing of the 7 different outlet sizes can be achieved? For example, a bladder could be blow moulded, with the tooling being modified using inserts to obtain variable size of bladder with the same tooling. Does anyone know of any extruded seals that may be able to achieve the required inflation and deflation? Would fabricating two extruded seals together (with one valve) be a feasible option for achieving the inflation required? Any suggestions or guidance would be useful, regarding the design, possible manufacturing processes and potential suppliers that you may recommend (considering that I am based in the west London/Heathrow airport area – although I am open to suggestions of suppliers anywhere in the world).