Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02248~31 1998-09-2~
TITLE: METHOD AND APPARATUS FOR PREVENTING
WATER FROM STAGNATING IN BRANCHES OF A
MUNICIPAL WATER SUPPLY SYSTEM
FIELD OF THE INVENTION
This invention pertains to installations for recirculating water in
water piping systems and more particularly, in branches and dead-ends of
municipal water supply systems.
BACKGROUND OF THE INVENTION
Plumbing regulations and plumbing codes are very specific about
preventing cross connections in a piping system and generally, licensed
plumbers are apprehensive of these problems. A 'cross connection' is
defined in plumbing code books as any actual or potential connection
between a potable water system and any source of pollution or
cont~min~tion.
It is generally accepted that st~gn~nt water should always be
considered cont~min~ted and non-potable. Further, it is believed that
stagnant water is not only found in marshes and ponds, but is also found in
water piping systems and reservoirs that do not have sufficient flow to keep
the water active, where water remains still for long period of time for
example. Although the fact is often neglected, decaying water in a piping
system is in direct contact with potable water and represents a cross-
connection cont~min~tion that is believed to be harmful to the health of
users supplied in water by that piping system.
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Generally, municipal water supply systems are flushed periodically
to discharge st~gn~nt water. It is often the case that the discharged water
has a foul odour and filthy discolouration. Despite these periodic flushes,
it is believed that the stagnation of water in municipal piping systems is a
S major cause of bad water taste, buildup of sediments in residential hot
water rese-voirs, and bacterial growth in toilet reservoirs and in drains of
bathroom accessories. It is further believed that st~gn~nt water in a piping
system is a source of many persistent illnesses, digestive problems and the
beginning of many diseases to those using and drinking water from those
I o systems.
Another reason for periodically flushing water supply systems is to
elimin~te concentrations of chlorine or other disinfectant used in water
supply systems which tend to accumulate at regions of low flow. In
addition to being detrimental to a good health, high concentrations of
15 chlorine in particular, are known to change the PH value of the water and
to deteriorate the protective coating inside water pipes. The material of
fabrication of the pipes, which may contain traces of toxic substances are
then exposed to the potable water.
The problem of water stagnation is particularly noticeable near
water hydrants for example and at the ends of long branches of a piping
system where the number of users on a branch pipe IS not sufficient for
ensuring a proper circulation of water. These situations are often found in
newer or partly built subdivisions, and at the end of streets which are
supplied in water by oversized pipes. Furthermore, a number of
municipalities have water supply systems that were designed according to
fire prevention requirements. The size of many branch pipes in these
systems is often too large to ensure an adequate circulation of water within
the pipe under normal conditions.
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The problem of st~gn~ting water in municipal water supply systems
has been generally overlooked in the past, and therefore, there are no
known system or method for preventing such degradation of water quality.
SUMMARY OF THE INVENTION
In the present invention, however, there is provided an installation
for connection to a water piping system comprising a water main and at
least one branch pipe, for preventing a stagnation of water inside that
branch pipe. In a first aspect of the present invention, the installation
comprises a yull~ing unit connected to first and second openings in the far
end of the branch pipe relative to the water main. The pumping unit has an
inlet connection connected to the first opening and an outlet connection
connected to the second opening for pumping water out of the branch pipe
through the first opening, and back into the branch pipe through the second
opening. The installation also comprises a conduit extending inside the
branch pipe from the second opening to a proximity of the water main.
The pumping unit is continually or intermittently operable for
sampling a portion of the still or slow moving water at the far end of a
branch pipe, and for pumping these water samples near the water main
where the water flow inside the pipe is more active. Such circulation of
water in a branch pipe prevents the stagnation of water at the far end of the
branch pipe. Further advantages of the installation of the present invention
is that a connection thereof to a branch pipe of an existing system is doable
without excavating the entire branch pipe. The setting of the pumping unit,
the first and second openings and the conduit inside a branch pipe can be
effected through a relatively small hole dug in the ground near the far end
of the branch pipe. Therefore, the cost to a municipality for retrofitting an
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existing water supply system with several installations of the present
invention is relatively small as compared to the cost of re-sizing the entire
supply system to ensure an adequate active flow inside each branch pipe.
In accordance with another aspect of the present invention, the
5 pumping unit comprises a tubular casing and a pump mounted inside the
tubular casing. The tubular casing has a closed end and an openable end.
The tubular casing has inlet and outlet connections extending through the
wall thereof. These inlet and outlet connections are releasable-type
connections. The pump has inlet and outlet fittings respectively connected
o to the inlet and outlet connections. There is also provided a rod connected
to one of the inlet and outlet fittings and extending to the openable end of
the casing. This rod is usable for working the pump in and out of the
releasable connections. When the tubular casing is buried into the ground
with the openable end extending above the ground surface, the pump is
15 removable from inside the casing for m~intçn~nce or for replacement for
example, by a person standing above ground working the rod.
In accordance with another aspect of the present invention, the
pumping unit comprises a submersible-type pump enclosed in a cartridge
having an inlet opening connected to the inlet connection of the casing and
20 an outlet opening connected to the outlet connection of the casing. The
submersible-type pump is advantageous for its capacity to deliver relatively
high pressure and flow rate where required to satisfy a large number of
water system requirements.
In accordance with yet another aspect of the present invention, there
25 is provided a method for preventing stagnation of water in a water supply
system having a water main, a branch pipe connected to the water main and
a branch valve connected between the branch pipe and the water main. The
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method comprises the steps of extracting water samples from the far end
of the branch pipe relative to the water main and pumping the water
samples into the near end of the branch pipe through the branch valve and
toward the water main. When samples of water from the far end of a
S branch pipe are periodically or continually recirculated into the near end
of the branch pipe relative to the water main, a freshening of water in that
branch pipe is effected and water stagnation is prevented.
In accordance with yet a further aspect of the present invention,
there is provided a pumping apparatus comprising a tubular casing having
10 a closed end and an openable end. A pump is mounted inside the casing.
There are also provided an inlet adapter extending through the casing and
being connected to the inlet fitting of the pump, and an outlet adapter
extending through the casing and being connected to the outlet fitting of the
pump.
In such an apparatus, the casing and the pump are positional in the
ground and the inlet and outlet adapters are connect-able to an underground
piping system for pulllpillg fluid through the piping system. This pumping
unit is convenient for installation near the end of a branch pipe of a water
20 supply system without having to built expensive vaults or other
underground enclosures to house the pump. Other advantages of the
pumping apparatus include the fact that it is manufacturable with
commercially available pumps and releasable fittings and common water
pipes. The pumping apparatus are manufacturable in few standard sizes
25 and can be connected to a water supply system using lengthy flexible pipes.
Therefore, the ~U~ g a~p~al-ls of the present invention is self-contained,
easily manufacturable, easily storable in standard sizes, and adaptable to
a variety of situations and ground conditions.
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BRIEF DESCRIPTION OF THE DRAWINGS
The preferred embodiments of the invention will be further
understood from the following description, with reference to the drawings
in which:
FIG. 1 is a cross-section view of a main water supply line, a side view of
a branch pipe extending from the main line, and an elevation view
of an apparatus of the first preferred embodiment connected to the
end of the branch pipe;
FIG. 2 is a partial cross-sectional view of a branch pipe and a cross-
sectional view of a recirculating ~wllpillg unit of a first type usable
inside the apparatus of the first preferred embodiment;
FIG. 3 is an enlarged cross-sectional view of a typical anchoring
arrangement on a recirculation conduit;
FIG. 4 is a partial cross-sectional view of the pumping apparatus of the
first pl~ell~d embodiment showing a recirculating pwllpillg unit of
the first type usable inside the apparatus of the first preferred
embodiment;
FIG. 5 is a partial cross-sectional view of the pwllpillg apparatus of the
first preferred embodiment showing a pWll~ lg unit of a second type
usable inside the apparatus of the first preferred embodiment;
FIG. 6 is an elevation view of the pumping apparatus of the first preferred
embodiment with shut-off valves mounted thereon;
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FIG. 7 is a transversal cross-sectional view through the casing of the
pumping a~pa itlus shown in FIG. 6, as seen along line 7-7 in FIG.
6, in which the illustration of a pump has been omitted for clarity;
FIG. 8 is a cross-sectional plan view of a hydrant connection and a
recirculating conduit extending therein;
FIG. 9 is a side view of a typical hydrant installation and of a recirculation
conduit extending near the hydrant's valve;
FIG. 10 is cross-sectional view of a branch pipe illustrating piping
connections for an alternate installation of the apparatus of the first
preferred embodiment near a hydrant take-off connection;
FIG. 11 is a side view of an installation of the pumping apparatus of the
first plere-led embodiment on a loop pipe in a water supply system,
for recirculating water in that loop pipe;
FIG. 12 is a cross-sectional view of a pumping apparatus of a first
preferred embodiment wherein a pu~ g unit is usable as a booster
pump for increasing the water pressure inside a branch pipe, and an
apparatus of the second plere--~d embodiment cont~inin~ a pressure
regulating valve, for recirculating water in the branch pipe.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Reference will firstly be made to FIG. 1 illustrating a typical
installation of a pumping apparatus of a first preferred embodiment for
recirculating water in a branch pipe. Before describing this installation in
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detail, however, it is deemed that certain general information should be
reminded in order to afford a clearer understanding of the diagram of FIG.
1.
A municipal water supply system generally comprises a main pipe
5 20, or a water main in common terms, and several branch pipes 22
extending away from the main pipe 20. The branch pipes 22 typically
supply water to residences on side streets for example. In many
municipalities, however, newer streets have few houses therealong and the
ends of those streets are generally last to be developed. A branch pipe 22
10 supplying water to few houses at the far end of a street is nonetheless a
same diameter over the full length of the pipe. Therefore, the water inside
the branch pipe 22 near the far end of the street remains still for long
periods of time and tends to stagnate.
It is customary with municipal water supply systems to install fire
15 hydrants (not shown) at regular intervals along a branch pipe and at the
very end of the branch pipe. These fire hydrants are opened periodically
for flushing stagnant water out of the ends of branch pipes. However, these
periodic flushes are only a temporary remedy and not a cure. Therefore it
is common with municipal water supply systems that the water drawn from
20 a branch pipe 22 far from the water main 20 contains a high coliform
count.
In the illustration of FIG. l, the pumping apparatus of the first
preferred embodiment 28 is installed near the end of a branch pipe 22 for
pumping water from the end of the branch pipe, through a conduit 94
25 extending upstream inside the branch pipe 22 to a region in the branch pipe
where the water flow is more active.
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The pumping apparatus of the first preferred embodiment 28
comprises a vertical cylindrical casing 30 enclosing a pumping unit (not
shown). The inlet 32 and outlet 34 pipes to and from the ~ lpillg unit are
connected to the far end of the branch pipe 22 using a pair of saddle-type
5 hole covers 36,38, sometimes referred to as "Clear Way"TM adapters.
The recirculation conduit 94 inside the branch pipe 20 preferably
extends from the far end of the branch pipe to a region near a branch valve
40 used to isolate the branch pipe 22 for the water main 20. The
recirculation conduit 94 inside the branch pipe 22 is preferably anchored
1 o to a third saddle-type adapter 42 and a first pipe stem 44 extending through the saddle-type adapter and inside the branch pipe 22.
Branch valves 40 are typically installed at short distances from a
water main 20 between the water main 20 and a first take-off connection
15 (not shown) to a first residence along that branch for example. Thus, the
water circulation inside the branch pipe near the branch valve 40 is
normally maximum for that branch pipe 22. When a branch pipe has
several residences connected to it, the water near the inlet of the branch
pipe is more active than at the far end of the branch pipe. Therefore a
20 recirculation of water from the far end of a branch pipe to a region where
the water is active prevents the water from st~gn~hng near the far end of
the branch pipe.
The apparatus of the first preferred embodiment 28 is preferably
installed near the far end of a branch pipe 22 along a street right-of-way for
25 example. Electrical power for the ~w-l~ing unit inside the casing 30 of the
apparatus is preferably supplied through an underground cable 50 from a
power supply unit 52 mounted on a nearby hydro pole 54. The power
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supply unit 52 preferably has a power meter and an adjustable timer for
intermittently operating the pump of the apparatus. It will be appreciated
that the pumping unit and timer may also be operated from a remote
location through co~ ul~ication lines or other signal tr~n~mit~ing devices.
The pumping apparatus of the first preferred embodiment 28 is
preferably installed in the ground with the upper portion of the casing 30
extending above the ground. The pumping unit inside the casing 30 is
thereby accessible for inspection or servicing for example.
A pair of shut-off valves 60,62 are also preferably provided on or
near the apparatus of the preferred embodiment 28 for isolating the
recirculating pump when required, from the pressure inside the branch pipe
22. Each shut-off valve preferably has a valve stem 64,66 extending near
the surface of the ground, near a street curb for example, as it is customary
with the valves of a municipal water supply system.
The installation of the apparatus of the first preferred embodiment
is thereby effected without excavating the entire branch pipe 22. The
installation of the lJul~ g a~p~lus 28 at the far end of an existing branch
pipe is relatively easily done without great expense to a municipality. The
installation of the recirculation conduit 94 inside the branch pipe is done
from the far end of the branch pipe using various methods known to
plumbers and in particular by using a plumbing snake or a high pressure
pipe cleaner with a self-propelled-type nozzle for example.
Referring now to FIGS. 2 and 3, the pumping apparatus of the first
preferred embodiment 28 and a preferred installation of the recirculation
conduit 94 inside the branch pipe 22 are illustrated therein in greater
details. The vertical cylindrical casing 30 of the apparatus of the first
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preferred embodiment 28 encloses a recirculation pump 70 of a f1rst type
having an inlet connection 72 and an outlet connection 74. Each
connections 72,74 comprises a standpipe adapter coupling 76 or 78 often
referred to as a "pitless adapter"TM. This type of adapters has a wedge-type
5 connection inside the casing 30 in which it is installed for receiving a
fitting on eq~lipment inside the casing, and a conduit extending through the
wall of the casing.
The outlet connection 74 of the pump 70 preferably has a pipe or
10 other rod-like member 80 extending upwardly and an eye hook 82 at the
upper end of the rod-like member 80 for working the pump 70 into and out
of the standpipe adapter couplings 76,78.
The inlet and outlet pipes 32,34 are preferably made of a flexible
potable grade material and have a substantial length for accommodating
15 situations where the branch pipe 22 is located under the pavement of a
street and the casing 30 of the apparatus is installed along the outside edge
of a sidewalk for example. The recirculating conduit 94 is also preferably
made of a flexible potable grade material.
As mentioned earlier, the inlet pipe 32 is preferably connected to the
20 far end of a branch pipe 22 by means of a first saddle-type adapter 36. The
outlet pipe 34 is also connected through the branch pipe 22 by means of a
second saddle-type adapter 38. The outlet pipe 34 is connected to a second
pipe stem 90 extending through the second saddle adapter 38 and into a
f1rst T or elbow f1tting 92.
The recirculation conduit 94 ex~Pn(l.c from the first T or elbow fitting
92 to a second T-f1tting 96 near the branch valve 40. The fitting 96 is
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anchored to the branch pipe 22 by means of the first pipe stem 44 threaded
through the third saddle-type adapter 42. The first pipe stem 44 preferably
has a tapered pipe thread portion 100 for effecting a sealed connection into
the third saddle-type adapter 42, and a straight thread portion 102 for
S connecting into the T-fitting 96. The T-fitting 96 being under water, the
sealing of the threaded portion 102 into the T-fitting 96 is not critical and
therefore a straight thread cormection at this location is acceptable. The
pipe stem 90 has a similar configuration for anchoring the fitting 92 to the
second saddle-type adapter 38.
lo The preferred pipe size for the recirculation conduit 94, the inlet and
outlet pipes 32,34 and the associated fittings are between about nominal 1.0
inch to about nominal 1-1/2 inches, when the branch pipe size is about
nominal 6-8 inches in diameter for example.
The T-fitting 96 further has a nozzle 104 connected thereto and
15 oriented to eject water through the branch valve 40 and beyond the branch
valve 40 towards the water main 20. Although the pressure through the
nozzle 104 should preferably be sufficiently high to eject water into the
water main 20, this feature is not essential for ensuring an adequate
recirculation of water in a branch pipe 22 for preventing stagnation of
20 water at the far end of that branch pipe 22. A distance 'A' between the
branch valve 40 and the water main 20 is usually less that 10-15 feet. The
leng,th 'B', however, can be as long as a mile or more. Therefore, as it was
mentioned before, the flow of water through the branch valve 40 when
there is a substantial number of residences connected to that branch pipe
25 22 is sufficient to ensure a freshness of the water inside the branch pipe atthat location. Hence, a mixin~; of the water from the far end of the branch
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pipe 22 with the water near the branch valve 40 is quite appropliate for
preventing the stagnation of water near the far end of the branch pipe 22.
Referring now particularly to FIGS. 4 and 5, the ~umping apparatus
28 of the first preferred embodiment is illustrated therein at a larger scale
5 than in the previous drawings. The cylindrical casing 30 of the apparatus
of the first preferred embodiment preferably has a cap 110 on the upper
extremity thereof for allowing access inside the casing for servicing the
pump 70 for example. The cap 110 is preferably a lockable-type cap
having holes therein (not shown) for receiving a padlock 112.
As will be appreciated, the recirculating pump in the apparatus of
the first pr~f~lled embodiment 28 may be a submersible type pump 114 as
illustrated in FIG. 5 to satisfy a particular in~t~ tion or a preference of the
m~mlfacturer of the al~aralus. In this case, the submersible-type pump 114
is installed in a closed cartridge 116 having a bottom opening connected to
15 the inlet connection 72 and a top opening connected to the outlet
connection 74.
The length of the casing 30 is preferably sufficient to ensure that the
pump 70 or 114, and the inlet and outlet cormections 72,74 are located
below the frost level when the apparatus of the first preferred embodiment
20 28 is installed in colder regions.
Referring now to FIGS. 6 and 7, one variant of the pumping
apparatus of the first preferred embodiment of the present invention has
both shut-off valves 60,62 located adjacent the casing 30 of the apparatus.
25 In this variant, a brace member 120 is provided for circling the cylindrical
13
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casing 30 and for clamping and guiding both valve stems 64,66 in a fixed
alignment with the longitudinal axis of the casing 30. One of the shut-off
valves, the inlet shut-offvalve 60 in these illustrations, is preferably offset
relative the outlet shut-offvalve 62 when viewed from the upper end of the
casing 30. For this purpose, a 22-1/2~ elbow 122 is preferably installed
between the inlet shut-off valve 60 and the inlet standpipe adapter 76.
Another variant installation of the apparatus of the first preferred
embodiment is illustrated in FIGS. 8 and 9. In these illustrations, a fourth
saddle adapter 130 is installed adjacent a take-off connection 132 to a fire
0 hydrant 134 for example, for anchoring the recirculation conduit 94 near
the take-off connection 132. A further T-fitting 136 is spliced into the
recirculation conduit 94 in line with the take-off pipe 132. A secondary
conduit 138 having a nozzle 140 on its far end is connected to the T-fitting
136. Hence, when the pump 70 or 114 operates, the water from the far end
l 5 of the branch pipe 22 is pumped through the recirculating conduit 94 and
through the secondary conduit 138 for displacing the water inside the take-
offpipe 132, for re~çhing through the hydrant's isolating valve 142 and for
washing the hydrant's valve 144 and therefore, for also preventing a
stagnation of water inside the take-offpipe 132. It will be appreciated that
a capacity of the pumping unit 70 or 114 is determined according to the
length and elevation of the branch pipe 22 and also to the number of fire
hydrants 134 along that pipe 22.
In the light of the present disclosure and of the illustration of the
accompanying FIG. 10, the person skilled in the art will appreciate that the
inlet and outlet pipes 32,34 for the in~tallation of the pumping apparatus of
the first preferred embodiment may also be located near a fire hydrant take-
off pipe 132. Thus, when the far end of a branch pipe 22 is not easily
14
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accessible, a fire hydrant take-off connection 132 may be temporary
removed for inserting the recirculation conduit 94 and a suction conduit
146 extending to the far end of the branch pipe 22.
Referring now particularly to FIG. 11, there is illustrated therein, a
further variant installation of the pumping apparatus of the first preferred
embodiment 28. In this installation, the apparatus 28 is connected to a loop
pipe 150 having both ends (not shown) connected to the main line 20 of a
water supply system. This type of piping system is common under streets
having traff1c circles or in large subdivisions having a plurality of
quadrivial street arrangement. These loop pipes are also used for feeding
water to large buildings such as schools, stores and factories. St~gn~nt
water is also found in these loops, especially during vacation time when
several occupants are gone for extended periods.
The pumping apparatus of the first preferred embodiment 28 is
preferably installed in combination with a check valve 152 which is
preferably installed near one end of the loop. In this typical installation,
the inlet pipe 32 is connected to a saddle-type hole cover 154 on the loop
pipe 150, on one side of the check valve 152. The outlet pipe 34 is
connected to another saddle-type hole cover 156 on the loop pipe 150 on
the other side of the check valve 152. The pump 70 is used for
recirculating the water around the loop to prevent stagnation in that loop
pipe 150.
The illustration of FIG. 12 is referred to for describing yet another
variant installation of the pumping apparatus of the first preferred
embodiment 28. In this further installation, the pull~ing apparatus 28 is
used for increasing the pressure in a branch pipe 22. In this installation,
the apparatus 28 of the first preferred embodiment is also used in
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association with a check valve 160, and with an al,p~lus of the second
preferred embodiment 162. The inlet pipe 32 of the pulllping apparatus of
the first preferred embodiment 28 is connected to a saddle-type hole cover
164 on the branch pipe 22, on the upstream side of a check valve 160. The
outlet pipe 34 is connected to another saddle-type hole cover 166 on the
branch pipe 22 on the downstream side of the check valve 160. The pump
114 is used for increasing the pressure in the downstream side of the check
valve 160 relative to the upstream side. The check valve 160 may be
installed anywhere along a branch pipe 22 where the pressure inside the
lo pipe is known to fall below a preferred level.
The apparatus of the second preferred embodiment 162 comprises
a casing 170 much like the casing 30 of the ~ ing apparatus 28 of the
first preferred embodiment. There are also provided an inlet and outlet
standpipe adapter couplings 172,174, and inlet valve 176, an outlet valve
178, and inlet pipe 180 and an outlet pipe 182. The inlet pipe 180 is
connected to an inlet saddle-type hole cover 184 and extends inside the
branch pipe to the far end of the branch pipe 22. The inlet pipe 180' is
preferably anchored to the far end of the branch pipe, at 186, when the hole
cover 184 is at a substantial distance from the far end of the branch pipe.
The outlet pipe 182 is cormected to a saddle-type hole cover 188,
and extends inside the branch pipe 22 to an anchor point 190 near the
branch valve 40 (not shown), such as in the in~t~ tion illustrated in FIGS.
1 and 2. The outlet pipe 182' has a nozzle 192 as in the previously-
described installations.
16
CA 02248~31 1998-09-2~
When the booster pump 114 operates, the pressure at the far end of
the branch pipe 22 is raised above the pressure in the upstream side of the
check valve 160. Thus, the water from the far end of the branch line 22 is
forced through the inlet pipe 180', through the apparatus of the second
preferred embodiment 162 and out through the outlet pipe 182' and nozzle
192 to recirculate water from the far end of the branch pipe 22 to a region
near the main line 20. In order to m~int~in a higher pressure on the
downstream side of the check valve 160, there is provided a pressure
regulating valve 194 mounted inside the casing 170 of the apparatus of the
second preferred embodiment 162 . This pressure regulating valve 194 is
connected in-line between the inlet adapter coupling 172 and the outlet
adapter coupling 174. A pair of pressure gauges 196,198 are also provided
near the upper end of the casing 170 for mo~ o. ;.~g the pressure at the inlet
and outlet adapter couplings 172,174 respectively. The adjustment knob
200 of the pressure re~ ting valve 194 is also preferably located near the
upper end of the casing 170 such that an adjustment of the valve 194 may
be effected from the surface of the ground through the access cover 202 of
the apparatus of the second preferred embodiment 162.
Accordingly, the combination of the apparatus of the first and
second preferred embodiments 28,162 is usable for ~iml~lt~neously
increasing the pressure in a branch pipe 22 of a water supply system, and
for recirculating the water in that branch pipe for preventing a stagnation
of water at the far end of that branch pipe.
While the above description provides a full and complete disclosure
of the preferred embodiments of this invention, various modifications,
alternate constructions, alternate uses and equivalents may be employed
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without departing from the true spirit and scope of the invention. Such
changes might involve alternate components, structural arrangements,
construction features or the like. Therefore, the above description and the
illustrations should not be construed as limiting the scope of the invention
5 which is defined by the appended claims.
18
