Title: Fluid dispensing piston

Abstract: A fluid dispensing piston for a cylindrical dispensing tube has a recessed transverse end wall formed with at least one aperture. The aperture is normally covered by a fluid seal removably retained on the exterior surface of the end wall. The piston is placed in a cylindrical dispensing tube with the exterior of the end wall pressing against the fluid in the tube and the piston is moved axially down the tube to dispense the fluid. Further fluid may then be added to the tube and a second piston moved axially down the tube to dispense that fluid, the conformable material covering the aperture in the end wall of the first piston being forced away from the end wall to uncover the apertures as the second piston is moved down the tube to create a pathway for the fluid through the first piston.

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Inventors: Farrell, III, Francis M. (Washington County, MN, US)
Otto, Robert B. (Champlin, MN, US)
Seim, William J. (Roseville, MN, US)

Application Number: 904600
Filing Date: 1978-05-10
Publication_date: 1979-12-18
Assignee: Minnesota Mining and Manufacturing Company (Saint Paul, MN)
Primary Class(es): 222/386 206/384
Other Classes:
US Patent Ref:

2815151	Dec, 1957	Collins	222/327.
3076456	Feb, 1963	Hun, Sr.	128/218.
3315847	Apr, 1967	Trumbull	222/327.
3659749	May, 1972	Schwartz	128/218.

Other Refs: 2358534276192

Jun, 1974	DE
Aug, 1927	GB

Primary Examiner: Marmor, Charles A.
Assistant Examiner:
Attorney: Alexander; Cruzan, Sell; Donald M., Qualey; Terryl K.