Moisture sensing device for pipes and the like

A moisture sensing device for application to water pipes and the like utilizes a pair of closely spaced electrical conductors partially positioned in an elongated flexible insulating member which can be adhesively affixed to a water pipe or the like with the spaced partially exposed electrical conductors in oppositely disposed relation to the pipe. An alarm actuating circuit is connected with the spaced conductors and arranged to initiate an alarm when moisture bridges the closely spaced conductors.

BACKGROUND OF THE INVENTION 
(1) Field of the Invention 
This invention relates to moisture sensing devices and circuits for the 
detection of water and other conductive fluids. 
(2) Description of the Prior Art 
Prior art devices incorporating moisture sensing elements are disclosed in 
U.S. Pat. Nos. 336,773, 3,732,556, 4,013,924 and 4,106,001. 
In U.S. Pat. No. 336,773 conductors are separated by a material which will 
absorb water so as to bridge the conductors. 
In U.S. Pat. No. 3,732,556 vertically spaced conductors are positioned 
around the edge of a swimming pool. 
In U.S. Pat. No. 4,013,924 conductors are positioned in normally dry and 
electrically insulating hygroscopic material which forms an insulating 
layer on a steam pipe or the like. Moisture leaking from the pipe is 
contained by the hygroscopic material which then becomes a conductor. 
In U.S. Pat. No. 4,106,001 a moisture detector for use with an undergarment 
discloses an adhesive strip having a pair of spaced conductors which can 
thereby be affixed to the undergarment. 
In the present invention the arrangement of the closely spaced electrical 
conductors in the elongated flexible insulating member with only small 
areas of the conductors surface exposed, forms a novel and very 
inexpensive essential element in a moisture sensing device as the device 
of the invention can be easily adhesively affixed along the bottom of a 
pipe to be supervised. 
SUMMARY OF THE INVENTION 
A moisture sensing device for pipes and the like consists of a sensing 
element comprising an elongated flexible insulating member having a pair 
of closely spaced electrical conductors partially positioned therein with 
limited surface areas exposed, the elongated flexible insulating member is 
easily attached as by adhesives to a pipe to be supervised as by running 
the same along the bottom thereof with the exposed portions of the closely 
spaced conductors in oppositely disposed relation to the bottom surface of 
the pipe. The moisture sensing conductors are connected to a circuit 
consisting of a transistor, relay, and power supply. The conductors, in 
the presence of moisture, cause the transistor to draw current energizing 
a relay which in turn actuates normally open and normally closed switches 
controlling desirable alarm devices.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
A moisture sensing device for pipes and the like disclosed herein consists 
essentially of a continuous strip water sensor 10 comprising a continuous 
elongated flexible insulating member 11 formed of a suitable synthetic 
resin such as polyvinyl chloride in which a pair of electrical conductors 
12 and 13 comprising multi-strand copper are largely embedded. 
In FIG. 1 of the drawings, the continuous strip water sensor generally 
indicated at 10 is shown affixed to the bottom of a water pipe 14 which in 
turn is suspended by pipe hangers 15 from an overhead support. The 
relative size of the pipe 14 and the continuous strip water sensor 10 may 
be seen in the cross section comprising FIG. 2 of the drawings. 
By referring now to FIGS. 3 and 4 of the drawings, enlarged bottom and 
cross sectional views of the continuous strip water sensor 10 may be seen. 
The continuous elongated flexible insulating member 11 having a width 
approximately one-eighth of an inch and a thickness slightly greater than 
1/32nd of an inch in the preferred embodiment and as seen in FIGS. 3 and 4 
of the drawings, the electrical conductors 12 and 13 are largely embedded 
in the flexible insulating member 11 so that only small areas of the 
conductors are exposed on the lower surface of the flexible insulated 
member 11 as best seen in FIG. 4 of the drawings. The electrical 
conductors 12 and 13 are spaced 3/64 of an inch. 
The upper transverse surface of the continuous elongated flexible 
insulating member 11 is substantially flat and a layer of a suitable 
adhesive 16 is preferably formed thereon along with a protective plastic 
film cover 17. A suitable adhesive that is self-adhering with respect to 
plastics and metal and many other materials is available under the 
trademark SCOTCH as manufactured by 3M Company of Minneapolis, Minn. 
Alternately, the continuous elongated flexible insulating member 10 may be 
coated with a similar adhesive in liquid form at the time the continuous 
strip water sensor is applied to the pipe. 
As seen in FIG. 1 of the drawings, the continuous strip water sensor 10 
shown continuously affixed as by the aforesaid adhesive to the bottom of 
the water pipe 14 and it will be understood that sections of plastic 
insulating film are applied to the inner surfaces of the pipe hangers 
where they cross the continuous strip water sensor 10 so that they will 
not short the conductors 12 and 13 which are exposed in the bottom most 
surface of the continuous strip water sensor 10 as hereinbefore described. 
In FIG. 2 of the drawings, it will be seen that if there is a leak in the 
pipe 14, the water leaking will run down to the bottom of the pipe and 
over the continuous strip water sensor 10 where it will bridge the closely 
spaced parallel conductors 12 and 13. 
By referring now to FIG. 5 of the drawings, a block diagrammatic circuit 
may be seen to which the conductors 12 and 13 are connected by terminal 
posts 18 and 19 respectively. The circuit of FIG. 5 of the drawings acts 
to originate an alarm upon the detection of water by the continuous strip 
water sensor 10 hereinbefore described. 
In FIG. 5 of the drawings, a 24 volt AC source of current is shown in 
connection with a bridge rectifier 20 which is grounded as at 21. The 
bridge rectifier 20 is connected with a 24 volt regulator 22 and the 
connection is grounded as at 23 by way of a 500 .mu..mu.F, 50 v DC 
capacitor 24. The current from the regulator 22 connects by way of a 
conductor 25 with the terminal post 18 and by way of a secondary 500 
.mu..mu.F, 50 v DC capacitor 26 with a conductor 27 which is connected 
with the terminal post 19 and with a transistor 28 by way of a 
15K.OMEGA.resistor 29. One terminal of the transistor 28 is grounded as at 
30 and another terminal thereof is connected with a 24 volt relay 31. The 
relay 31 operates to simultaneously make and break a pair of circuit 
switches 32 and 33 respectively which in turn are in connection with 
visual alarm devices 34 and 35 respectively. 
In a remote location such as a television transmitter translator operated 
by remote controls from a principal transmitter site, the terminals 34 and 
35 may supply a signal to a radio transmitter or the like capable of 
transmitting the signal to the principal transmitter site. 
It will occur to those skilled in the art that the moisture sensing device 
for pipes and the like as disclosed herein may be used in connection with 
supervising piping systems other than water systems and wherein the fluid 
has electrical transmission properties capable of bridging the conductors 
12 and 13 of the continuous strip water sensor 10 as heretofore described. 
It will thus be seen that a simple, inexpensive easily installed moisture 
sensing device has been disclosed which incorporates a novel continuous 
sensor that is applied directly to a pipe to be supervised and that when 
said sensor is electrically connected with a suitable alarm initiating 
circuit such as disclosed herein, an efficient dependable and extremely 
sensitive moisture sensing device is realized.