Oil-less pressure relief valves

A self contained one-way pressure relief valve for application over an opening in an exterior surface of packaging containing a gas producing product, the valve comprising:

• a gas impervious base layer having a top and a bottom;
• a gas inlet opening extending through the base layer from the top to the bottom of the base layer;
• a layer of adhesive on the bottom of the base layer around the gas inlet opening for attachment of the pressure relief valve to the exterior surface of the packaging;
• a gas impervious topmost layer spaced above the base layer and overlying the gas inlet opening extending through the base layer;
• a gas impervious intermediate layer having a top and a bottom and being between the topmost layer and the base layer;
• a gas flow opening extending through the intermediate layer from the intermediate layer bottom to the intermediate layer top, the intermediate layer gas flow opening being generally aligned with the base layer gas inlet opening;
• a one-way valve element between the intermediate layer and the topmost layer providing one-way gas flow from within the packaging through the opening in the surface of the packaging, the gas inlet opening, the gas flow opening, and out of the valve;
• a filter material layer between the intermediate layer gas flow opening and the base layer gas inlet opening;
• a gas impervious layer of adhesive between the intermediate layer and the filter material layer;
• and
• an opening extending through the layer of adhesive between the intermediate layer and the filter material layer, and generally aligned with the intermediate layer gas flow opening and the base layer gas inlet opening.

A self contained one-way pressure relief valve for application over an opening in product packaging containing a gas-producing substance, the valve comprising:

• a gas-impervious base layer having a bottom side for attachment to the packaging and a top side;
• an opening extending entirely through the base layer;
• a gas impervious adhesive-like material layer on the base layer top side around the base layer opening;
• and
• a gas-impervious release-film-coated membrane covering the base layer opening and being attracted to, and overlying, the adhesive-like material layer to block gas flow through the base layer opening and between the membrane and the adhesive-like material layer, the attraction being such that the membrane is at least partially separable from the adhesive-like material layer by pressure from within the packaging to permit one-way gas flow out of the package and valve through the base layer opening and between the membrane and adhesive-like material layer.

A self contained one-way pressure relief valve for application over an opening in product packaging containing a gas-producing substance, the valve comprising:

• a gas-impervious base layer having a bottom side for attachment to the packaging and a top side;
• an opening extending entirely through the base layer;
• a gas impervious adhesive-like material layer on the base layer top side around the base layer opening;
• and
• a gas-impervious release-film-coated membrane of a material having an attraction with the adhesive-like material layer, the membrane covering the base layer opening and overlying the adhesive-like material layer to block gas flow through the base layer opening and between the membrane and the adhesive-like material layer, the attraction being such that the membrane is held against the adhesive-like material layer until pressure from within the packaging against the membrane overcomes the attraction and at least partially separates the membrane from the adhesive-like material layer to permit one-way gas flow out of the packaging and valve through the base layer opening and between the membrane and adhesive-like material layer.