Accessory for underfloor duct systems

Application filed March 15, 1929. Serial No. 347.199

This invention relates to underfloor duct systems of the same general type as that described and claimed in my prior Patent No. 1,592,548 issued July 13, 1926, and is conβ cerned more particularly with an accessory to be used in such systems to close outlets, the use of which has been discontinued for any reason after, the installation is completed. While the utility of the new accessory is not 10 limited to any particular system, the accessory will be described in a form especially for use in conjunction with the system of the patent, with the understanding that this is done merely for purposes of illustration.

The system of ducts described in the patent includes a network of main and branch circuit ducts installed in the floor during construction, each duct being provided with a plurality.of outlets spaced at predetermined 20 uniform intervals. These outlets preferably take the form of tubular inserts mounted in the top wall of the duct and they are spaced it different distances in different systems, depending on the character of the service which 25 the system is to supply. For example, the space between adjacent inserts may be 24 or 30 for ordinary purposes.

In the installation of the duct in a concrete floor structure, it is the common practice to 30 lay the ducts on the top of the rough floor slab so that the ducts are embedded in the usual cinder fill .and lie a substantial distance between the finished floor surface. The inserts project upwardly toward the floor sur35 face and preferably terminate even with that surface, although they may terminate a short distance beneath it. The ends of the inserts at the time of installation are closed by small !. caps which are slipped in the ends of the in40 serts and are readily removable therefrom.

After the finished floor surface is completed, it is customary to cover it with linoleum, although in some cases wood flooring is similarly employed. The main and branch 45 circuit ducts lead to floor boxes, the tops of which are flush with the finished surface of the floor and the wiring is drawn through the ducts in the ordinary way and connections made at the boxes. Whenever service is de50 sired at a point along a duct, an opening is made in the linoleum over one of the inserts, the cap. removed, the wires drawn through the opening and duct to the nearest box, where the connection is made. The connection is then completed by the use of a stand 55 pipe fitting supported in the end of the insert, so as to lead the wires out of the system, to a point a few inches above the floor surface. This fitting is provided with a flange which overlies the linoleum and pro- 60 vides a substantially water-tight closure for the insert.

In some instances, after such a connection has been made, it may be desirable to discontinue it, and whenever this is done, the stand 65 pipe and the wires are removed. While the end of the insert may be closed by means of l ^caP) there is still an opening in the floor covering which is undesirable.

The present invention is, therefore, direct- 10 ed to the provision of an accessory for use in a system of this sort which is to be used to provide a neat water-tight closure for the outlets, the use of which is discontinued, this accessory not only serving to close the end ⁷⁵of the insert but also closing and concealing the hole in the floor covering. This accessory may be readily introduced into the end of the insert and may then be secured firmly in position therein, so that it will not become dis- 80 lodged accidentally. The accessory may be made in different sizes for use with inserts of diflerent diameters and it may be used m. the insert alone or in conjunction with a bushing employed in certain large inserts 85 to reduce the internal diameter thereof.

For a better understanding of the invention, reference may be had to the accompanying drawings, in which

Fig. 1 is a sectional view through a duct ⁸⁰and insert with the accessory in place taken on the line 1—1 of Fig. 2;

Fig. 2 is a sectional view on the line 2--2 of Fig. 1; and

Figs. 3 and 4 are longitudinal sectional ⁰⁵views through a duct insert, showing other uses of the accessory.

^Referring n°w,to the drawings, the duct 10 is illustrated as being of rectangular cross-section of suitable dimensions. This ¹⁰⁰

1,809,613 duct is provided with a plurality of inserts 11, one of which is shown. The insert is preferably a metal tube inserted into an opening in the top wall of the duct and hav⁵ ing its lower end flanged over, as indicated at 12. In order to hold the insert in position in the duct wall, it is provided with a circumferential rib 13, which engages the top wall of the insert. The duct with its inserts 10 is mounted in the floor structure 14 and the insert extends upwardly from the duct substantially to the surface of the floor. This insert is closed by a small removable cap during installation and prior to use.

When an outlet connection is to be made, the floor covering 14', which is here illustrated as linoleum, is cut to provide an opening directly above the top of the insert, the location of the insert being determined by 20· measuring along the duct from the adjacent box. The cap is then removed through the opening, the wiring fished through the insert and duct to the box where the connection is made, and the installation completed by a ²⁵ stand-pipe which is introduced into the end of the insert and has a flange which overlies the linoleum near the hole cut therethrough.

. When service is discontinued, the removal of the stand-pipe leaves the insert open. This ³⁰ open insert could be closed by means of the original cap, but if this were done a hole in the linoleum would be visible. In order to take care of this situation, the present accessory has been devised. This accessory con³⁵ sists of a tubular stem 15, the lower end of which is slotted, a? indicated at 16. This stem has a diameter such that it may be readily received in the insert and the upper end of the stem is closed by a cap 17, which has ⁴⁰ a flange 18 which projects beyond the wall of the stem. The cap is relatively thin and its thickness decreases from its center toward its periphery, so that at its outer edge its thickness is relatively small. Through an ⁴⁵ opening in the top of the cap extends a screw 19 which is threaded at its lower end into a wedge nut 20. This wedge nut has the shape of a truncated cone and its outer tapering wall 20' ha? an average diameter substan⁵⁰ tially that of the inner diameter of the stem 15.

When service is discontinued at any outlet and the wiring and stand pipe removed, the stem of the accessory is inserted into the ⁵⁵ tubular insert, the nut at this time being free of the slotted end of the stem. When the accessory has been placed in position with the flange 18 resting tightly against the floor covering, the screw is turned and the nut 20 ⁶⁰ is drawn up against the slotted end of the stem engaging the inner edge thereof. By reason of the shape of the nut, the slotted portions of the stem are expanded by it so as to grip the inner wall of the insert tightly. 65 Only a few turns of the screw is necessary for this purpose and the accessory is then locked rigidly in position and cannot be accidentally dislodged. By reason of the relative thickness of the cap 17 closing the upper end of the stem and its decreasing thickness toward the periphery, the presence of this cap above the floor covering is not at all objectionable and the flange protects the covering around the opening and at the same time provides a neat finish. _7S

Should service be required at the outlet thus closed by the accessory, the accessory may be readily removed by turning the screw so as to release the nut from the edge of the stem. The accessory may then be readily ₈₀removed by a suitable tool inserted beneath the edge of the flange.

As illustrated in Fig. 1, the accessory has a form suitable for use in an insert of ordinary size, the stem having an outer diameter 85 substantially the same as the inner diameter of the insert. In some instances, duct systems are provided with large inserts, such as that shown at 21 (Fig. 3). The insert here shown is mounted in the wall of the duct in 90 the same manner as illustrated in Fig. 1 and the insert has a diameter at its top less than the diameter of the opening in the duct wall. This type of insert is frequently macle with a thread 22 rolled in its wall near the top. In 95 an insert of this type, it is customary to employ a bushing 23, the outer wall of which is threaded to engage in the threads- of the insert. The bushing has an interior diameter substantially the same as the plain insert 11. 100 With this bushing, the accessory may be used in the manner previously described, the expansion of the stem of the accessory causing it to grip the bushing rather than the inner wall of the insert. The accessory is used jo5 in the same manner previously described. In Fig. 4 there is shown a construction involving the use of an insert 24 of large diameter, the insert being of the same diameter from one end to the other and without the no threads 22. In this case, the bushing 25 is a cylindrical form and held in place by friction. The accessory is used with this bushing in the manner above-described.