Note: Descriptions are shown in the official language in which they were submitted.
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~ CA 02325409 2000-11-07
24P3CA
Water Sensor Device
The present invention relates to a water sensor device and is useful in
particular, but not
exclusively, for sensing the chemical and/or other properties of water being
supplied to a
swimming pool or a hot tub.
In order to test the water supplied to swimming pools and hot tubs, to ensure
that the
water has the correct chemical properties required to ensure the safety of
uses of the
swimming pools and the hot tubs and the correct functioning of ancillary
systems, it has
previously been necessary to employ chemical test kits and colorimetric
evaluations.
Based on the results of measurements thereby obtained, various chemicals are
added to
the water in order to improve the chemistry of the water. These procedures are
time-
consuming and inconvenient.
It is accordingly an object of the present invention to provide a novel water
sensor device
which simplifies and facilitates the testing of the quality of water being
supplied, for
example, to a swimming pool or a hot tub.
According to the present invention, there is provided a water sensor device
comprising a
sensor body, water sensors mounted in the sensor body for sensing the
properties of
water, and a display for indicating outputs from the water sensors.
In a preferred embodiment of the invention, the sensors and the display are
interconnected by electrical circuitry which is accommodated in a water-tight
space in
the sensor body, and an electrical battery is provided for energizing the
sensors and the
display.
The battery is preferably provided in a housing which is removably fitted into
the sensor
body, and pH and Redox sensors may be provided in the housing.
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In a preferred embodiment of the invention, the display comprises diodes
controlled by a
microprocessor in the the electrical circuitry and a cover secured to the
sensor body and
extending over the water-tight space, the cover being at least partly
translucent to allow
illumination of the diodes to be observed from the exterior of the water
sensor device.
The electrical circuitry and the diodes are accommodated in a water-tight
space, and the
housing has a housing portion extending into the water-tight space and
provided with an
electrical connection between the battery and the electrical circuitry. The
housing is
sealed in a water-tight manner to the sensor body.
In use, the present water sensor device is installed in a pool or hot tub
water pipe using a
standard plumbing fitting, in such a way that the sensors are exposed to the
water in the
plumbing.
The present water sensor device is preferably provided with sensors for
sensing the pH
and the chlorine content of the water, and may also indicate whether or not a
pool filter
needs to be replaced or cleaned.
The present water sensor device may also include a sensor for detecting the
total
alkalinity of the water, which is of interest to pool users and maintainers
because mineral
salts have a tendency to precipitate in boilers and filters associated with
swimming pools.
The invention will be more readily understood from the following description
of an
embodiment thereof given, by way of example, with reference to the
accompanying the
drawings, in which:-
Figure 1 shows a view through a water sensor device embodying the present
invention
taken in vertical cross-section along the line 1 - 1 of Figure 4.
Figure 2 shows a view taken in cross-section along the line 2-2 of Figure l;
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Figure 3 shows a top plan view of the water sensor device of Figure 1;
Figure 4 shows an underneath plan view of the water sensor device of Figure 1;
and
Figure 5 shows a circuit diagram of a control circuit of the water sensor
device of Figures
1 to 4.
As shown in the accompanying the drawings, a water sensor device indicated
generally
by reference numeral 10 has a sensor body 12 provided with a cover, indicated
generally
by reference numeral 13, which is formed by an annular molding 14 and a disk
16 fitted
into the annular molding 14. The cover 13 is secured to the sensor body 12 by
screws 15.
The disk 16 is made of transparent plastic material, and the molding 14 and
the sensor
body 12 are made of suitable plastic material.
A housing indicated generally by reference numeral 18 is fitted into the
sensor body 12
and has an upper portion indicated generally by reference numeral 20 which
projects into
a water-tight space 22 formed in the housing and closed by the cover 13. The
housing 18
also has a lower portion indicated generally by reference numeral 21,
enclosing a battery
compartment 23, and the upper portion 20 is heat-sealed to the lower portion
21 so as to
close the top of the battery compartment 23. A sealing ring 24 is provided
between the
housing 18 and the sensor body 12 to provide a water-tight seal between these
components.
The water-tight space 22 accommodates a circuit board 26 provided with a
plurality of
diodes 28.
The battery compartment 23 accommodates a battery 30 which, at its upper end,
is
connected by an electrical connection 32 extending through the top portion 20
of the
housing 18 into electrical contact with the circuitry on the circuit board 26.
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In addition to the battery 30, the housing 18 is provided with a reference
cell comprising
a silver/silver chloride electrode 35 immersed in a silver chloride solution
37 serving as
an electrolyte, in an electrolyte compartment 39 in the housing. A porous plug
41 on the
bottom of the housing allows for the diffusion of the charged ions and the
completion of
the electrical circuit between a pH sensor 33 and a Redox sensor 33A. The pH
sensor 33
is in the form of a glass bulb sensor of high impedance, which senses the pH
value of
water diffusing into the pH sensor, and the Redox sensor 33A comprises a
graphite or
precious metal electrode adjacent to the pH sensor. Alternatively the pH and
Redox
sensors may be removed from the housing 18 and attached to the lower part of
the sensor
body 12. In this way, when the reference sensor electrolyte is exhausted or
the battery is
dead, only the housing 18 needs be replaced.
The sensor body 12 is formed with a frusto-conical lower portion 34 which is
threaded
for threaded engagement with a standard pipe fitting, which is not shown. The
sensor
body 12 is also formed with four or more through-openings 36 (Figure 2) for
receiving
other water quality sensors. These other sensors may comprise conductivity
sensors,
pressure sensors, and the pH and Redox sensors if these are not incorporated
in the
housing 18.
Referring now to Figure 3, which shows a plan view of the disk 16 forming part
of the
cover 13, it will be seen that a disk 16 days provided with the lettering
indicating three
water qualities, namely pH, chlorine and total alkalinity. Each of these
qualities is
associated with three window openings 40 through which illumination of
respective
diode 28 can be observed from the exterior of the water sensor device 10, the
remainder
of the disk surface being covered with paint.
The top surface of the disk 16 is also provided, as shown, with three
different letterings
indicating, respectively, "Too Low", "OK" and "Too High".
CA 02325409 2000-11-07
The electrical circuitry on the printed circuit board 26 is illustrated in the
circuit diagram
of Figure 5 and has input terminals T1 - T2, which are connected to the ph
electrode, the
chlorine electrode, the reference electrode, an alkalinity sensor and a
temperature sensor,
respectively. The terminals T1 and T2 are connected to a pair of high
impedance
differential amplifiers Al and A2, and switches S1- S4 connect to a
microprocessor in
the form of a microcontroller 42 which controls the diodes 28.
The present sensor device is not restricted to the sensors mentioned above but
in addition,
or alternatively, may be provided with sensors for temperature, etc. Also, by
measuring
the back pressure against a filter (not shown), and by comparing this
measurement with a
corresponding measurement value obtained when the filter is new, it is
possible for the
sensor device 10 to provide an indication of whether or not the filter needs
to be replaced
or cleaned.
The housing 18, containing the battery 13 and the reference cell, may be
designed to have
a battery capacity and a projected reference cell life such that the housing
18 and its
contents form a replaceable unit which will last a complete pool season, i.e.
about 6-7
months, before needing replacement. At the beginning of each season, the owner
or
maintainer will install a replacement unit comprising a new housing 18 with
its
associated battery and sensors. The sensor device 10 will then automatically
carry out a
calibration sequence so that the water sensor device 10 would become fully
operable in
an automatic manner, i.e. without further human input.
As will be apparent to those skilled in the art, various modifications and
improvements
may be made in the above-described water sensor device.
For example, it is envisaged that the water sensor device may be equipped with
a low
power radio transmitter for transmitting numerical values of the various
parameters of the
water being monitored to a display unit, which may, for example, be mounted in
the
CA 02325409 2000-11-07
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user's home. This would eliminate any need for the pool owner to visit a pool
shed or
pump room to view the water chemistry values.
Instead of employing a radio link for this purpose, it would also be possible
to provide an
electrical connection between the water sensor device and the display in the
user's home.
It would also be possible to modify the present device so as to permit the
user or
maintainer of the pool not only to access the water chemistry values remotely
but also to
determine in advance the amount of chemicals required to be added to the
water.
Furthermore, the present sensor device may be modified to act as a controller
for
metering devices dispensing appropriate quantities of chemicals, in liquid or
dry form,
into the pool water in order to maintain the water quality and balance
automatically with
minimal operator intervention.
