Note: Descriptions are shown in the official language in which they were submitted.
CA 02639600 2008-09-15
TESTING APPARATUS AND METHOD FOR VALVES
FIELD OF THE INVENTION
The present invention relates to a testing apparatus and method for evaluating
the operation of
air-release/vacuum-breaker combination valves, of the type commonly used in
municipal water
distribution pipeline networks.
BACKGROUND OF THE INVENTION
Municipal water distribution systems encompass hundreds and thousands of
kilometres of
underground watermains for a medium to large city. A very important role for
maintaining the
normal parameters of water delivery within this network of pipes is played by
various valves and
fittings. An illustrative example from this class is the air-release valve, a
type of mechanical
device placed on watermains. Air-release valves are designed to open
automatically to the
atmosphere whenever they detect pockets of air trapped in the watermains, yet
are also designed
to close automatically after all the air is purged to prevent any significant
loss of liquid. Air
trapped in the watermains would otherwise cause a series of problems ranging
from total
blockage of water flow (the so-called "air lock") to insufficient flow rates
(trapped air acts
similar to a solid obstruction inside a pipe, effectively reducing the
available flow path for water)
to complaints from end users due to noisy pipes and sputtering, gurgling or
turbulent flow when
opening faucets.
Vacuum-breaker valves play an equally important but opposite role on
watermains: they open
automatically to allow air to be drawn into the water pipe. This is useful
when only a portion of a
watermain needs to be emptied of water, as the air allowed in by the vacuum-
breaker valve will
speed up the draining and will prevent the siphoning of water from
neighbouring portions of the
watermain.
Advances in this field in the past 50+ years have lead to the introduction of
the air-
release/vacuum-breaker combination valve, a device that combines the two above-
mentioned
roles into one robust package. Due to their higher original price, these
combination valves were
installed in the beginning only on the few largest watermains in a given
distribution system. As
the price of the combination valves went down in time, and as municipalities
came to appreciate
their importance, the installed base of combination valves has greatly
expanded and they are now
in widespread use on smaller watermains. A medium to large, modem municipal
water
distribution system contains hundreds and thousands of such valves,
distributed over a large area.
While these valves are generally of a robust construction and can work
unattended for years and
decades, they are nonetheless subject to corrosion, seizing, clogging and
mechanical failure.
Moreover, few municipalities were historically aware of the need for regular
inspection and
maintenance for these valves, and even fewer were willing or able to budget
the expense of
implementing such a program. This situation is starting to change, and it is
estimated that many
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CA 02639600 2008-09-15
more municipal waterworks departments across North America have started or
intend to
implement regular inspection, testing and maintenance programs, covering
hundreds of
thousands of such combination valves.
Inspecting, testing and performing maintenance on these valves is a difficult
and unpleasant task.
They are usually located in dark, cramped underground chambers, often under
the surface of
major streets. The valves are quite large and heavy, as the typical material
of construction for the
valve body has historically been cast iron. After decades spent underground,
many valves display
heavy external corrosion. It is exceedingly difficult to perform any valve
testing and maintenance
in a cramped, dark underground chamber under a busy street. The logical
alternative is to install
a new or reconditioned valve and take the old valve out.
While the price of new valves has come down in recent years, it is still high
enough to warrant
not discarding an old valve at the first sign of malfunction. A typical course
of action in
municipal practice is to discard any valves older than 10 to 20 years and to
attempt to repair and
recondition newer valves. As a result, it is expected that hundreds of
thousands of such valves
will likely have to be reconditioned across North America in the near to
medium future. It is very
expensive to ship such heavy pieces of equipment to any regional valve repair
centre and even
more expensive to ship them back to manufacturers (most of which are offshore
in Asia). As a
result, most of the reconditioning and testing of the valves will likely have
to be done locally, in
the maintenance shop of a municipal waterworks department.
An essential part of the process is the final testing to ensure that the
operational capability of the
reconditioned valve has been restored to a satisfactory level. We are unaware
of any prior art
related to any device or method for comprehensive testing of all functional
features of a
combination valve under stringent parameters that simulate real-world
conditions. Currently, the
testing is typically done by connecting the valves to a garden hose and
filling them with water to
check for leaks; this provides no confirmation of proper working for the air-
release or vacuum-
breaking mechanisms inside the valve.
Even when such a "hose tested" reconditioned valve is further taken out in the
field and is
installed on "live" watermains (at a significant cost in manpower and time),
the only features
thus tested are, at best, the absence of leaks and the ability to withstand
the system pressure. On a
"live" watermain, there are no ready means to test a valve's air-release
abilities unless, by a
stroke of luck, several air pockets happen to be traveling through that
particular watermain at that
particular time and in a spot just upstream from the newly installed valve.
Furthermore, if no air
release was noticed at the outlet of a valve being tested on the live
watermain, there would be no
ready means to know whether the tested valve did not release due to
malfunctionirig or due to the
fact that no air pockets were present in the watermain at the time to
challenge the air-release
mechanism.
There is a need for a fast, simple and effective testing apparatus and method
to allow full testing
of the operational capability of reconditioned combination valves, in the
comfort of a
maintenance shop, before deploying the valves in the field.
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CA 02639600 2008-09-15
SUMMARY OF THE INVENTION
The present invention is a simple, portable, inexpensive, comprehensive, easy
to operate and
effective apparatus and method for testing and evaluating the operational
capability, readiness
and performance of valves of the type commonly used in municipal water
distribution pipeline
networks.
The main part of the apparatus is a reservoir. The valve to be tested is
connected to a test port on
the reservoir, using the same fittings and preferably in the same position and
orientation as an
actual valve would be installed on a watermain in the field. Water at the
desired pressure is then
introduced into the reservoir and the test valve is checked for leaks.
Repeated small shots of
compressed air are then introduced into the reservoir, observing after each
burst whether the test
valve opens automatically to vent the air and whether, after each air-release,
the valve self-closes
immediately with minimal loss of liquid. The air and water pressure are then
released and the
vacuum-breaking test is performed by opening the test valve's drain port. If
the test valve does
not have a drain port, the reservoir is fitted with its own drain port that
can be open to perform
the vacuum-breaking test. The sound of air being drawn into the valve, and a
strong, steady
stream of water draining, are positive signs that the vacuum-breaking
mechanism works
properly.
In an aspect of the invention, the reservoir is of a cylindrical shape,
positioned so that its
longitudinal axis is in a generally horizontal orientation, and the test port
branches generally
vertically upwards from the reservoir and generally perpendicular to the
reservoir's longitudinal
axis.
In a further aspect of the invention, the reservoir consists of a cylindrical
portion of pipe, capped
at both ends, the pipe having a diameter between 1" and 100", chosen so as to
match and
simulate the type, construction materials, orientation and diameter of the
piping commonly used
for feeder mains and distribution mains on the municipal water distribution
pipeline networks.
In a particular embodiment of the invention, the test valve is an air-release
valve, of the type
commonly used in municipal water distribution pipeline networks.
In a further alternative embodiment of the invention, the test valve is a
vacuum-breaker valve, of
the type commonly used in municipal water distribution pipeline networks.
In a further embodiment of the invention, the test valve is an air-
release/vacuum-breaker
combination valve, of the type commonly used in municipal water distribution
pipeline
networks.
In a further embodiment of the invention, the method of testing comprises
hydraulic testing of
the test valves, using pressurized liquid.
In a further embodiment of the invention, the method of testing comprises
pneumatic testing of
test valves, using pressurized gas.
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In a further embodiment of the invention, the method of testing comprises
hydraulic and
pneumatic testing of valves, using pressurized liquid and pressurized gas.
In a further embodiment of the invention, the method of testing comprises
hydraulic, pneumatic
and vacuum testing of valves, using pressurized liquid, pressurized gas and
vacuum generated by
free-draining a liquid.
Further aspects of the invention will become apparent from the following
description.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic view of the apparatus, with a test valve shown connected
to the test port.
FIG. 2 is a photograph of the apparatus, with a test valve shown connected to
the test port.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to Figure 1, the apparatus comprises a reservoir 1, having a
hydraulic inlet port with a
first isolation valve 2, a pneumatic inlet port with a second isolation valve
3, a pressure
measurement port 4, and a test port 5 for receiving a test valve. A pressure
gauge is connected to
the pressure measurement port 4 and displays the internal pressure in the
reservoir. The test port
is fitted with a third isolation valve 7, a drain port 8 and a test valve
receptacle 9. For the
purpose of testing, the test valve 10 is connected to the test valve
receptacle 9.
The reservoir 1 is preferably made from a cylindrical section of pipe, capped
at both ends. To
ensure that the testing apparatus simulates accurately the valve's real-world,
field operating
conditions, it is preferable that the piping type, construction materials,
orientation and diameter
of the reservoir are so chosen so as to match and simulate the actual piping
type, construction
materials, orientation and diameter offeeder mains and/or distribution mains
on the municipal
water networks on which the tested valve will eventually be installed.
A typical testing methodology includes one or more of the following steps:
a) connecting the test valve 10 to the valve receptacle 9 on the test port 5;
b) connecting a source of pressurized water to the hydraulic inlet port 2,
opening the first
isolation valve on the hydraulic inlet port and allowing the pressurized water
to flow into
the reservoir 1 until the desired test pressure is read on the pressure gauge
6;
c) opening the third isolation valve 7 so that the water pressure is equalised
between the test
valve 10 and the reservoir 1;
d) observing the presence or absence of air and water discharges from the
outlet and from
the seals and joints of the test valve 10. A properly functioning valve will
not leak water
through any seals or joints, will release quickly any air with a "whoosh"
sound and will
shut off by itself with minimal water release. A valve that continuously leaks
water from
the seals, joints or outlet will be marked as failing the test.
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CA 02639600 2008-09-15
e) connecting a source of compressed air to the pneumatic inlet port 3 and
introducing a
short burst of compressed air into the reservoir 1 by briefly opening the
second isolation
valve on the pneumatic inlet port.
f) observing the presence or absence of air and water discharges from the
outlet and from
the seals and joints of the test valve 10. A properly functioning valve will
not leak water
through any seals or joints, will release quickly any air with a "whoosh"
sound and will
shut off by itself with minimal water release. A valve that does not release
air or that
continuously leaks water from the seals, joints or outlet will be marked as
failing the test.
g) shutting off the third isolation valve 7;
h) starting to drain off the water from the test valve 10 by opening the drain
port 8 or, if the
test valve 10 is equipped with its own drain port, by opening the drain port
on the test
valve 10;
i) while draining the water from the test valve 10, observing whether air is
being drawn into
the test valve's outlet. Also observing the flow properties of the stream of
liquid draining
from the drain port. A noticeable noise of air being drawn in, and a strong,
steady stream
of water flowing from the drain port, are confirmation that the vacuum-
breaking
mechanism works properly. If no air sucking noise is detected and the stream
of draining
water is weak and unsteady, the valve should be marked as failing the test.
