Food Processing Applications for Inflatable Seals

The Client:

A food processing company.

The Situation:

During the processing of foodstuffs, i.e., mashed potatoes, the material is dispensed from a large kettle-like container into packaging containers. The material (mashed potatoes) must be forced out of the large container cleanly in a metered amount.

Application Requirements:

As the foodstuffs material is forced out of the large container (drum or vat), there is a need to seal the surface between "the plunger" and the side of the vat, and to scrape the sides of the container of any foodstuff material that is adhered to the sides of the vat.

Approach:

The surface between the "plunger" and the side of the vat is sealed with an inflatable seal mounted into the rim of the "plunger" that inflates radially outward.

	(Figure A)

The challenge is to seal the surface with enough force to scrape the foodstuffs material from the sides of the container without generating excessive force on the sides of the container that will cause the seal to rotate (roll) out of its mounted position. (Typically the seal at this point begins to act as a brake on the sides of the vat. See figure B.)

	(Figure B)

The Solution:

In this application (mashed potatoes), a radially outward G-34 cross section inflatable seal produced from FDA-grade white nitrile material was utilized.

The Result:

The mashed potatoes were successfully processed from the bulk batch into smaller packages.

Other "Drum-Follower" Seal Implications:

Whether the application is processing of mashed potatoes, tomato sauce, or petroleum caulking compounds, the same challenge is present, i.e., move the material from the large container while scraping the container walls and balancing the requirements for scraping against the natural tendency for the seal to act as a brake and roll out of the mounting channel.

The ideal solution for difficult "drum-follower" applications is to fully restrict the movement of the seal by locking it into the mounting channel and permitting the seal to actuate a "shoe" which performs the sealing/scraping function required.

	(Figure C)

The "shoe" then becomes a consumable part that can be discarded should it ever become worn out. The environment (temperature, pressure, exposure to chemicals, etc.) dictates the selection of the materials chosen to produce the inflatable seal and the "shoe."