Abstract: An air velocity gauge for direct measurement of low air flow or draft rates in the range of 20-400 feet per minute comprising a generally flat housing of quadrilateral shape defining a draft way therethrough and a set of opposed draft way inlet and outlet openings that are aligned with the plane of the housing that approximate the size and general shape of the way. A vane formed from a strip of Mylar polyester film is suspended pendulum fashion from the upper portion of the housing adjacent the draft way inlet and is creased longitudinally of same to rigidify the vane to act as such rather than as a flexible flap. The housing itself is in the form of an open centered center frame with open sides, to each side of which is applied a transparent side plate held in place by an adhesively backed opaque scale or scale plate that adheres to lands defined by the housing center frame for this purpose.

Abstract: A differential pressure gauge of the type comprising a controlling magnetic helix device carrying a pressure indicating arm, the position of which is controlled by a magnet mounted on the free end of a cantilevered leaf spring actuated by a pressure diaphragm exposed to differential pressures. The helix cooperates with a magnet having a planar pole face paralleling the axis of the helix and defining a magnetic axis that is normal to and intersects the helix axis. The gauge housing defines an integral one piece pressure wall that separates the helix from the magnet and defines within the gauge housing pressure cavity an operating space within which the magnet and its supporting leaf spring are mounted and operate. Between the helix and the magnet the pressure wall is of film dimensions and is contoured to stress in bending. The leaf spring is mounted on a mounting plate disposed within the pressure cavity and engaging the gauge housing only at its rim for stress isolation purposes.

Abstract: A differential pressure gauge of the type comprising a controlling magnetic helix device carrying a pressure indicating arm, the position of which is controlled by a magnet mounted on the free end of a cantilevered leaf spring actuated by a pressure diaphragm exposed to differential pressures. While the helix is preferably of the monoflange or single lobe type, either single or double lobe forms may be employed and they cooperate with a parallelepiped shaped magnet having a planar pole face paralleling the axis of the helix and defining a magnetic axis that is normal to and intersects the helix axis. The magnet and helix are closely spaced, and the magnet is formed from a suitable high energy product type material. The gauge housing defines an integral one piece pressure wall that separates the helix from the magnet and defines within the gauge housing pressure cavity an operating space within which the magnet and its supporting leaf spring are mounted and operate.