Oil-less and wetted pressure relief valves having an integrated filter

A one-way pressure relief valve having a particulate filter for attachment over a vent on an exterior surface of a closed package containing a gas-producing product, the pressure relief valve comprising:

• a filter layer of a strip-type material having a periphery and first and second sides defining a body therebetween, the filter layer having a filter element in the strip-type material providing passage of gas through the body and obstruction of particulate matter;
• adhesive on the filter layer second side to adhere the pressure relief valve to the exterior surface of the closed package;
• and
• a flexible seal joined selectively to the filter layer first side to form a gas flow path between the flexible seal and the filter layer first side along an unjoined region of the flexible seal and filter layer from the filter element to the filter layer periphery, the flexible seal having a first position in which the unjoined region seals the filter element to obstruct gas flow through the body and a further position in which the unjoined region is spaced at least partially from the filter layer first side and the filter element by gas pressure exerted through the filter element to permit one-way gas outflow through the gas flow path,
• whereby, the pressure relief valve enables one-way pressurized gas outflow from an interior of the closed package through the filter element and the gas flow path while preventing particulate matter from interfering with sealing of the filter element once gas pressure inside the package is decreased.

A one-way pressure relief valve having a particulate filter for attachment over a vent on an exterior surface of a closed package containing a gas-producing product, the pressure relief valve comprising:

• a filter layer of a strip-type material having a periphery and first and second sides defining a body therebetween, the filter layer having a filter element in the strip-type material providing passage of gas through the body and obstruction of particulate matter;
• an adhesive on the second side of the filter layer to secure the pressure relief valve to the exterior surface of the closed package;
• a closure along the filter layer first side and overlying the filter element;
• and
• a flexible cover layer overlying the closure and joined selectively to the filter layer first side to form a gas flow path between the closure and the filter element first side from the filter element toward the filter layer periphery, the flexible cover being movable between a first position holding the closure against the filter element to seal the filter element and obstruct gas flow through the body and a further position in which the closure is spaced at least partially from the filter layer first side and the filter element by gas pressure exerted through the filter element to permit one-way gas outflow through the gas flow path,
• whereby, the pressure relief valve enables one-way pressurized gas outflow from an interior of the closed package through the pressure relief valve while preventing particulate matter from interfering with sealing of the filter element once gas pressure inside the package is decreased.

A one-way pressure relief valve for application to a package comprising:

• a gas-impervious base layer having first and second sides and an opening entirely through the base layer through which gas enters the pressure relief valve and adhesive on the second side to secure the pressure relief valve to an exterior surface of the package;
• a first gas-impervious layer over the base layer and around the base layer opening;
• a flexible cover over the base layer;
• a second gas-impervious layer supported by the flexible cover across the base layer opening, the first and second gas-impervious layers having an attraction which holds the first and second gas-impervious layers together to form a seal blocking passage of gas from the base layer opening and between the first and second gas-impervious layers;
• and
• a filter layer with a filter element therein, the filter layer being between the base layer and the first gas-impervious layer and the filter element being over and aligned with the base layer opening, the filter element permitting gas flow through the filter layer toward the first and second gas-impervious layers while obstructing movement of particulates past the filter layer,
• whereby, pressure from within the package exerts a force which overcomes the attraction and at least partially separates the first and second gas-impervious layers permitting gas flow therebetween and out of the pressure relief valve.