Abstract: A backflow prevention apparatus of light weight, modular construction which provides quick and easy access to internal check valves. The backflow prevention apparatus generally comprises a tubular valve body having a lateral opening, at least one check valve positioned within the flow stream of the tubular valve body, a movable sleeve which fits over the valve body and is configured to cover the lateral opening in the valve body, and seals, associated with the sleeve valve body, for providing a fluid tight seal between the sleeve and valve body. The tubular valve body has openings at first and second ends, and the lateral opening is flangeless. Preferably, the backflow preventer includes a first, upstream check valve and a second, downstream check valve each having thereon a stop or ridge thereon.

Abstract: A check valve apparatus, usable in a double check valve backflow preventer apparatus, comprising a valve seat, a clapper pivotally coupled to the valve seat, a seal positioned to sealingly engage the clapper and valve seat when the clapper is closed against the seat, and a closure mechanism. The closure mechanism includes a first linkage element pivotally associated with the valve seat at a first pivot point located upstream from the seal, a second linkage element which is pivotally coupled to the first linkage element at a second pivot point, and which is pivotally associated with the clapper at a third pivot point, and a bias element associated with at least one of the linkage elements and configured to exert a closure force on the clapper.

Abstract: An image comparison apparatus and method for use in preoperative planning procedures which provides for superposition of a transparent medium with an image thereon, such as a medical x-ray, and a computer-interfaced display screen, and which allows a user to size, orient and spatially manipulate a digital image of on the display screen with respect to the superimposed medical transparency. A computer associated with the display screen periodically receives information updates for displayable images from product and advertising sources and electronic catalogs. The computer also transfers data to market services.

Abstract: A double check valve backflow prevention apparatus of lightweight modular construction. The apparatus comprises a primary housing component having a flangeless lateral opening, a first check valve module which fits within the lateral opening a second check valve module which also fits within the lateral opening a central housing component, with the central housing fitting within the lateral opening between the first check valve module and second check valve module. A first fluid tight seal is positioned between the first check valve module and central housing component, and a second fluid tight seal is positioned between the second check valve module and central housing component. A third fluid tight seal is positioned between the first check valve module and the primary housing component, and a fourth fluid tight seal is positioned between the second check valve module and the primary housing component.