Tamper-Resistant Flow Control Attachment for Shower Arm

1. Field of the Invention

This invention relates generally to flow control attachments that are resistant to tampering.

2. Background of the Invention

As the use of commercial establishments of volumetric flow limiting devices in plumbing systems becomes more prevalent, the incidence of theft and other tampering with such devices has significantly increased. Because the cost of replacing stolen or damaged flow limiters may be substantial in establishments where large numbers of these devices are employed, techniques have been sought to eliminate or at least discourage such tampering.

The present invention provides a tamper-resistant attachment adapted for installation between a shower arm and shower head. The attachment comprises a generally tubular housing having a longitudinal axis, an outer, generally cylindrical surface, an inlet portion adapted to be coupled to a shower arm and an outlet portion adapted to be coupled to a shower head. A flow control device for limiting the volumetric flow rate through the attachment is enclosed within the housing. The housing is secured against rotation relative to the shower arm by means of a set screw. The outer surface of the housing is provided with an annular groove. An outer, generally tubular shell is disposed about the housing and covers both the set screw securing the housing to the shower arm and the annular groove. The shell also includes means, preferably a set screw of the Allen head type, which projects into the annular groove for limiting the axial movement of the shell relative to the housing. The shell, however, is freely rotatable relative to the housing so that any attempt to remove the attachment in the absence of a special wrench will be discouraged. Any attempt to unthread the attachment from the shower arm results only in rotation of the outer shell relative to the housing.

Further objects, advantages and features of the invention will become apparent from a reading of the detailed description below when taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a side elevation view of a typical shower installation employing the tamper-resistant flow control attachment of the present invention; and

FIG. 2 is a side elevation view, partly in cross-section, of a tamper-resistant flow control attachment according to the present invention.

As shown in FIG. 1 a typical shower installation employing the present invention includes a tamper-resistant flow control attachment 10 threadedly secured to a shower arm 12 and a shower head 14 is in turn connected to the attachment.

With reference to FIG. 2, the attachment 10 includes a generally tubular housing 16 having a longitudinal central axis 18. The housing 16 further has an internally threaded inlet portion 20 adapted to be received by the shower arm and a necked down, externally threaded outlet portion 22 for receiving the shower head.

Between the inlet and outlet portions, the housing 16 defines a central portion 24 enclosing a volumetric flow control device 26 of the type disclosed for example in U.S. Pat. No. 3,995,664, issued Dec. 7, 1976, to the present inventor. The control device 26 functions to limit the water flow rate to a predetermined level, for example, 3 gpm, thereby conserving water and concomitantly the energy required to heat it.

The housing 16 also includes a generally cylindrical outer surface 28 having an annular groove 30 therein positioned in the central portion of the housing.

The inlet portion 20 has a radially oriented set screw 32 adapted to engage the threads of the shower arm thereby locking the housing against rotation once installed. The set screw 32 is of the type requiring a special wrench and may, for example, be of the Allen head type.

Enclosing the inlet and central portions of the housing 16 is an outer tubular shell 34 covering and thereby concealing both the set screw 32 and the annular groove 30. The upper or inlet end of the shell 34 may be provided with an inturned rim 36 for engaging the inlet end of the housing 16. A set screw 38 of the same type as the screw 32 is retained in the wall of the shell 34 and projects into the annular groove 30. It will be readily apparent that the outer shell is freely rotatable relative to the housing 16 but is constrained axially by the set screw 38 and groove 30.

The attachment is installed by threadedly fastening the housing to the shower arm, driving the set screw 32 into a locking engagement with the shower arm threads, sliding the tubular shell over the housing and finally turning the set screw 38 to project into the groove 30. The free rotatability of the outer shell and the concealment of the inner set screw 32 thereby effectively discourage attempts to remove the attachment in the absence of the special tool.