Abstract: The shroud is formed from sheet material and is cylindrical in shape. A plurality of spacers are associated with the sheet material. These spacers are designed to engage the outer surface of a duct to hold the cylindrical sheet material in radially outwardly-spaced relationship to the duct, defining thereby an insulating air gap between the outer surface of the duct and the shroud. The angular space between the spacers serves as gas channels to permit gas to flow between the shroud and the outer surface of the duct, along the length of the duct. The shroud has a straight axially-extending slot along its entire length for easy removal from a duct. An axially-extending edge receiving pocket is formed on the shroud adjacent to the slot for receiving the adjacent longitudinally extending edge of the slot to hold the shroud in a cylindrical shape and to provide a gas tight closure for the slot.

Abstract: A blanket is held in position on a bed by means of adjustable electrically conductive snaps connected between the blanket and the sheet or mattress cover. The snaps are connected to an electrical circuit in such a way that an alarm sounds when the snaps are disconnected.

Abstract: A housing for an electrical circuit is to be releasably mounted in an explosion-proof box without modifying the structure of the box. The housing is provided with at least one spring which extends away from the housing into engagement with an inner surface of the box. This engagement between the spring and the inner surface of the box deflects the spring, exerting force on the housing in such a way as to resiliently hold the housing inside the box.

Abstract: A support for stools or tables is formed from two identical hollow plastic sections. The sections are generally conical in shape so that they can fit inside each other for stacking purposes when not in use. The smaller end of each section is provided with interlocking means so that the sections may be releasably secured together to form a stool or support for a table.

Abstract: A two-wire frequency to DC converter utilizes a multistage binary counter which is controlled by a crystal oscillator and the input frequency. This arrangement provides precisely shaped square wave pulses at the output of the counter whose frequency is functionally related to the input frequency and which can be fed into a low pass filter to obtain an average DC value for the AC input. The output terminal at each stage of the binary counter has a plurality of open terminals, each associated with a particular frequency. By connecting a single diode across a selected open terminal, the converter which is constructed without regard to any input frequency, so it can be mass-produced, can be easily customized for a particular input frequency range.

Abstract: The flexible ball joint is provided with a bellows which is protectively mounted inside a shell. A portion of the shell serves as the spherical socket and a portion of a sphere serves as the ball for the ball joint. The ball is mounted in the socket and is concentric therewith. One end of the bellows is attached to the shell and the other end is attached to the ball. A plurality of generally equally angularly-spaced Purbon buttons are mounted on a support ring which is mounted on the surface of the socket. These buttons are in engagement with the surface of the ball so the ball joint can pivot freely over a wide range of temperatures. A generally spherical shell-like member is mounted in fixed and closely-spaced concentric relation to the outer surface of the spherical socket to limit axial movement between the socket and the ball and hold the Purbond button on the support ring. In addition, the shell-like member has formations shaped to define cooling channels for the protective bellows.

Abstract: A hollow seat post has a seat attached at one end while the opposite end is split defining an aligning pin receiving groove. One portion of the split end is provided with longitudinally spaced pin receiving holes. A coil spring is inserted inside a frame seat post. A small pin extending through the bottom of the frame seat post serves as a stop for the coil spring. A second pin extends through the upper portion of the frame seat post and aligns the seat when the seat post is inserted inside the frame seat post with the second pin in the groove in the seat post. A lever actuated pin is mounted on the frame and is positioned so the pin is in alignment with a hole extending through the frame seat post and can move therein. When the seat post is inserted in the frame seat post and the hole in the frame seat post is aligned with one of the holes in the seat post, the lever actuated pin penetrating both holes holds the seat at the desired level.