Moisture alarm

A moisture alarm comprises a watertight system with three probes extending down as supportive legs and as ballast from a floatable body or case containing audible and/or RF pulsing-alarm circuitry responsive to moisture detected by any or all of the probes; the case is upwardly convex on top to slip from beneath fixed obstacles in rising water; a provision prevents the probe from shorting out when the unit is set on a metal deck; the free ends of the probes, each of which has a set of outer and inner coaxial electrodes, are apertured, providing access for moisture to reach the inner electrode; a mercury switch sounds the alarm when the unit is tipped over in position lifting inner electrodes from the floor but can be over-ridden by a shunt which permits the unit to be operated inverted as a randdrop alarm; a dual ring conductor embodiment is also disclosed.

This invention relates generally to alarm systems and particularly to an 
alarm system for warning of the presence of water or the like. 
Millions of dollars are lost annually by homeowners, industries and 
insurance companies, to name a few, from water damage which timely warning 
could have prevented. 
Water-alarm systems of various types are known in the prior art, as 
indicated by the following U.S. Pats.: 
No. 3,122,736 to R. B. Weber, 2-25-64, discloses a body-attached battery 
operated signalling unit which activates in water by motion of a switch; 
No. 3,278,921 to M. Horino, 10-11-66, discloses a self-contained, floating, 
battery operated, pulsing, water-on-electrode activated signalling unit; 
No. 3,824,460 to R. V. Gustafson, 7-16-64, discloses a leakage sensor for 
floors; 
No. 4,020,417 to A. W. Brehob and C. E. Wheeler, 4-26-77, discloses use of 
a moisture probe in a battery powered pulsing-signal unit. 
In addition, bell-ringing rain warnings of the type exemplified by U.S. 
Pat. No. 1,217,036 have long been known; such use a variety of actuation 
means, including float switches, spring-biased switches held open by a 
tension member of ordinary paper which will tear when wet, etc. 
However, no known system is believed to provide the advantages which the 
present invention will, including those set forth in the following 
objects. 
Principal objects of this invention are to provide a self-contained, 
self-powered moisture detection system which provides an audible alarm 
when in contact with moisture, which is self-protective and can prevent 
submersion and thus provide the alarm at full strength regardless of water 
level and which is difficult for rising water to defeat. 
Further objects are to provide a system as described which can be used as a 
rain detector and can activate before the surface on which it is resting 
receives any moisture, a system which can be used on conductive floors 
such as steel as well as on non-conductive floors, and which can respond 
to small traces of water such as high humidity will sometimes produce. 
Among the locations in which the present invention could be used to monitor 
for flooding are basements, pump houses, storage areas, laundry rooms and 
open areas and the like, and much loss of time and effort can be avoided 
as well as monetary loss through such use. For example, the invention, 
being portable, can be used to warn of incoming water from river or stream 
flooding. Because sump pumps and drains clog, some people sleep in the 
basement so that they can have earlier warning of leakage from heavy rains 
or other flooding, and use of the invention could avoid need for this. 
Boats could have units according to this invention installed in the bilge, 
with or without special harness to hold the units, and the alarm could be 
remotely broadcast by radio frequency as by walkie-talkie, or even by 
integral transmitter. Vaults and contents and other closed areas lacking 
air circulation could be economically protected by alarms warning of 
build-up of excess humidity. Blowing rain could be detected at open 
windows and the alarm given. As another example, plumbers and others could 
use the invention to warn of leaks in piping of remote locations. 
During crisis times accompanied by or caused by flooding, electric power 
service is often interrupted, but such would have no effect on the 
self-powered self-protecting alarm system of this invention. 
In brief summary given as cursive description only and not as limitation, 
the invention includes a battery powered floatable alarm with probe feet 
and a convex upper part for preventing catching under obstacles when 
floating.

In FIG. 1 the view is slightly distorted for exposition to stress the 
non-overhang relation of the case at the probes. 
FIG. 1 shows major external features of the invention 10 which has the form 
of an upwardly convex or turtleshell-shaped case 18 with top 20, and with 
three moisture-sensitive probes 22, 24, 26 in the form of straight legs 
extending down from the bottom case perimeter parallel with each other. 
The plastic coaxial arcuate top 20 of the case unscrews to provide access 
to the interior. 
The case contains power and sensing and alarm and control elements 28, 30, 
32, 58, 60, 62, 50, etc. as will be described in reference to later 
Figures. These may be conventionally clamped in place. The case may be of 
thin metal such as aluminum and the probes may have similar thin metal 
tubing exteriors forming enclosing tubes which have respective watertight 
connections, as by welding, with the case. 
The lower end of each probe serves as an outer or first electrode 34, and a 
radial aperture 36 in this outer, tubular electrode for fluid to pass 
inward to a central or inner or second electrode 38 which extends down as 
a foot upon which the unit rests on a surface in the stable manner of a 
three-legged stool. 
In the Figures, the clearances between and below electrodes are exaggerated 
for exposition; they may be on the order of a fraction of a millimeter. 
FIG. 2 shows a bottom-end section of a typical probe 22, with outer 
electrode 34 and central electrode 38 sealed in coaxial spacing by 
conventional insulative material 40 such as solid polystyrene or other any 
suitable heavier than water dielectric. As indicated, one or more radial 
apertures 36 insure that fluid will have access to the interior to 
short-out the outer and inner or respective first and second electrodes 
and set-off the alarm circuit to attract attention to the leak or other 
cause of unwanted wetness in the area. The coaxial relation of the 
electrodes provides a multiplicity of actuation paths between them, any 
one of which will set off the alarm. 
FIG. 3 shows the bottom plan view with case 18 having the probes 22, 24, 
26, equally spaced around it, each having outer electrode 34 and central 
or inner electrode 38 separated by insulation 40, and apertures 36 in 
outer electrode. 
FIG. 4 shows a provision for using the probes on metal floors or on uneven 
conductive surfaces, to prevent shorting out the electrodes by means other 
than moisture. An insulative spacer 42 may be cemented on the bottom of 
each probe and preferably extends over and beyond the first electrode 
periphery a distance as an insulative margin. This may be plastic or it 
may be an insulative tape. 
This structure leaves the apertures 36 free to receive moisture but forms 
an insulative shoe on each probe for preventing shorting out by 
non-fluids. 
FIG. 5 shows how the case will float in upward position with the probes 
hanging down as ballast. This keeps the alarm portion up out of the water, 
assures that when the water drains away the probes will stll be in 
operating location, and permits the case to shed and slip from under fixed 
obstacles as at 45. 
FIG. 6 shows the invention 10 propped in inverted position in use as a 
raindrop alarm, raindrops R will short out the electrodes at the ends of 
the probes 22, 24, 26. Because the apertures 36 reach all the way to the 
insulation, the inverted probes form no cup, and raindrops can drain out 
so that the alarm will shut off when rain stops falling rather than 
running the batteries down. 
The prop 44 can be a ring such as a can top ring and will hold the unit 
stably upside down even though the top is made to be the lightest part, 
the batteries are placed low in the case along with other heavy parts. It 
is evident that the angle of support is somewhat adjustable because of the 
smooth overall convexity of shape. 
FIG. 7 diagrams features, some optional, which may be incorporated in the 
invention. Each of the three probes 22, 24, 26 has connections 46, 48 with 
amplifier, alarm and power supply circuits at 50, 52, and 54 in the case. 
All electronic circuits and elements are conventional and any suitable 
known circuits of the type may be used, those given later being typical 
examples. 
For the alarm, a pulse generator 56 may be used to produce an intermittent 
alarm sound through a speaker or horn 58 when the probes close the circuit 
in the presence of moisture. 
As an optional feature, an R. F. oscillator or generator 60 may be used to 
broadcast the alarm through an antenna 62, through a circuit 64 and switch 
66. If this feature is to be used the case should be of rigid 
thermoplastic such as polystyrene with the antenna inside. 
The main power switch is indicated at 28. If desired, a mercury switch 30 
may be incorporated to actuate the alarm should the unit be knocked over 
lifting the electrode from the floor at any time that the main switch is 
on, regardless of whether moisture is present. To inactivate the mercury 
switch when the unit is to be inverted as a raindrop alarm, a disabling 
switch 32 may be provided in series with it. A sensitivity selector for 
the probes may be provided as at 68. 
FIG. 8 gives details of a conventional circuit which may be used with the 
invention, except that parallel connection of the probes and the mercury 
switch and disabling switch for it are specific details of this invention. 
Power supply 54 may be a 9 volt battery, Mallory M N 1604 or equivalent. 
The three sets of electrodes respectively in 22, 24, 26 connect in 
series-parallel circuit 46, 48, through sensitivity switch 68 which is 
adjustable to three positions to vary resistance at 77, 79, 81 and connect 
through pin 15 to 70, the detector, which may be a Motorola microprocessor 
MC14466, to which pin the power supply also connects through resistor 72. 
To cause the alarm to sound when the unit is accidentally inverted, mercury 
switch 30 connects in parallel with the sets of electrodes in the probes, 
and to disable switch 30, permitting inverted operation, manual switch 32 
is provided in series with the mercury switch. 
Resistor 75 connects the power supply with pin 7 and resistor 76 similarly, 
through diode 78 connects it with pin 5. Capacitor 80 connects pin 12 to 
ground. Pin 11 connects through inverter 82 to sounder or horn 84 which 
may be a Sonalert SC12. The inverter may be a 2N3904 or 2N3906 and may 
connect through optional RF power switch 86, which may be a TIP122, to 88, 
a parallel-to-serial converter CD4021 or equivalent, provided with a 
conventional oscillator 90 and having conventional DIP switch 92 
connection to ground for selection of coding and an output through 60 
which may be a 2NS770 one-transistor pulse-modulated RF oscillator, which 
outputs through antenna 62. Any suitable RF receiver may be used such as a 
Linear Corporation Model Delta 3. 
Adjustment of the circuitry is conventional, the relative value of resistor 
75 and capacitor 80 being set for desired horn off-on timing. A test 
resistor 94 connecting with ground and pin 15 provides for testing by 
switch 96 across the probe lines with matching resistor 98 in series with 
one side. 
FIGS. 9 and 10 show a further embodiment, 900, except as noted similar to 
the first embodiment, but providing forsensing moisture in a circle equal 
to the diameter of the greatest dimension of the instrument. 
The electrodes include additionally first and second conductors 935, 937 
concentric with each other and with the housing 918, and forming a spaced 
double ring held by the three probes 922, 924, 926. The first and outer 
conductor 934 may be soldered or otherwise be electrically and 
mechanically affixed to the outer electrode 935 in each probe, clear of 
the inner electrode 938. Similarly the second or inner conductor 937 
secures electrically and mechanically to the inner electrode 938 clear of 
the outer electrode but in plane with it. The conduits may be of one 
sixteenth-inch (1.5 mm) diameter and of hard-temper copper spaced about 
twenty thousandths inch (0.5 mm) apart and extend in-plane with each other 
slightly below the lower ends of the three probes. To permit flow of 
liquid past the conduits each conduit may form a slight upward arch 939 at 
intervals between the probes. In this embodiment the diameter of the 
casing or housing may be substantially greater than the length of the 
probes, giving the whole apparatus a close-coupled aspect. Additional 
weight of the conduits helps ballast the instrument upright when floating. 
This invention is not to be construed as limited to the particular forms 
disclosed herein, since these are to be regarded as illustrative rather 
than restrictive. It is, therefore, to be understood that the invention 
may be practiced within the scope of the claims otherwise than as 
specifically described.