U.S. patent application number 13/246629 was filed with the patent office on 2012-03-29 for flow-rate activated safety vacuum release system.
Invention is credited to Joseph D. Cohen.
Application Number | 20120073040 13/246629 |
Document ID | / |
Family ID | 45869133 |
Filed Date | 2012-03-29 |
United States Patent
Application |
20120073040 |
Kind Code |
A1 |
Cohen; Joseph D. |
March 29, 2012 |
FLOW-RATE ACTIVATED SAFETY VACUUM RELEASE SYSTEM
Abstract
A Safety Vacuum Release System (SVRS) which incorporates a water
flow-rate sensor in electrical communication with the electric
motor which powers a swimming pool pump at an aquatic facility.
When the flow of water drops to a rate indicative of a flow
blockage at a suction outlet fitting within the pool, the SVRS
shuts down the electric pump motor to release a suction entrapped
bather. In one embodiment, the flow-rate sensor can be a transit
time or a Doppler unit which features a non-invasive, clamp-on
installation onto the circulation pipe. The SVRS can display the
real-time rate of flow of the circulation system, the real-time
turnover rate of the swimming pool, and signal the operator when it
is time to clean the pool filter. The SVRS can also maintain the
optimum flow rate of the circulation system by adjusting the speed
of a variable speed pump motor as hydraulic resistance changes.
Inventors: |
Cohen; Joseph D.; (Denver,
CO) |
Family ID: |
45869133 |
Appl. No.: |
13/246629 |
Filed: |
September 27, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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61386713 |
Sep 27, 2010 |
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61525339 |
Aug 19, 2011 |
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Current U.S.
Class: |
4/504 |
Current CPC
Class: |
E04H 4/1272 20130101;
E04H 4/12 20130101 |
Class at
Publication: |
4/504 |
International
Class: |
E04H 4/06 20060101
E04H004/06 |
Claims
1. An aquatic facility with a safety vacuum release system,
comprising: an aquatic vessel configured to contain a body of water
suitable for bathing; a circulation system for circulating the
water, wherein the circulation system includes: at least one
circulation intake; a circulation pump having a pump intake in
fluid communication with the circulation intake and a pump output
in fluid communication with a circulation output for directing the
water back into the aquatic vessel; and an electric motor for
operating the circulation pump; a flow-rate sensor in communication
with the circulation system to measure the rate of flow of the
water circulated by the circulation system; and the safety vacuum
release system in communication with the circulation system and the
flow-rate sensor, the safety vacuum release system to interrupt the
operation of the circulation pump by interrupting an electrical
power source in response to a particular flow-rate measured by the
flow-rate sensor.
2. The aquatic facility of claim 1, wherein the flow-rate sensor is
selected from a group consisting of a magnetic paddlewheel sensor,
a vortex shedding sensor, a turbine, a deflector, an ultrasonic
transit time sensor, and an ultrasonic Doppler sensor, and a
differential pressure sensor.
3. The aquatic facility of claim 1 further comprising a control
device having a processor, memory, a display device, and an input
device, the memory storing a minimum allowable flow-rate value and
a maximum allowable flow-rate value.
4. The aquatic facility of claim 3 wherein the control device
receives data signals from the flow-rate sensor and displays the
flow-rate of the water in real-time on the display device.
5. The aquatic facility of claim 4 wherein the processor receives
and processes data regarding the rate of flow of the water and
transmits processed data to the display device in real-time.
6. The aquatic facility of claim 3 wherein one or more software
programs executes on the processor, the software program to
generate a signal to terminate the operation of the circulation
pump, when the received rate of flow of water falls outside of a
range defined by the minimum allowable flow-rate value and the
maximum allowable flow-rate value.
7. The aquatic facility of claim 3 wherein the control device
displays a turnover rate for the body of water.
8. The aquatic facility of claim 3 wherein the control device
displays a percentage of the flow-rate that corresponds to a
flow-rate corresponding to a clean filter.
9. The aquatic facility of claim 3 wherein the control device
displays a percentage of the flow-rate that corresponds to a
flow-rate corresponding to a dirty filter.
10. A flow-rate activated safety vacuum release system comprising:
a circulation system for an aquatic vessel; a flow-rate sensor
operably engaged to the circulation system and configured to
determine a rate of flow through the circulation system; and a
control system in communication with the flow-rate sensor
configured to receive a signal related to the flow-rate through the
circulation system and provide one or more control signals to
control a pump of the circulation system.
11. The flow-rate activated safety vacuum release system of claim
10 wherein the one or more control signals enable or disable power
to be received at the pump.
12. The flow-rate activated safety vacuum release system of claim
10 wherein the one or more control signals for the pump are
generated in response to a hydraulic resistance causing a loss of
flow of water within the circulation system caused by a dirty
filter.
13. The flow-rate activated safety vacuum release system of claim
12 wherein the one or more control signals maintain a substantially
constant rate of flow of water within the circulation system.
14. A method for automatically releasing a bather trapped submerged
within an aquatic vessel having a water circulation system, the
trapped bather being held by a suction at a submerged suction
outlet fitting of the water circulation system, the method
comprising: circulating water in the water circulation system with
a pump powered by an electric motor, the water circulation system
having a normal operating range defined by a minimum allowable
flow-rate and a maximum allowable flow-rate; identifying an
occurrence of an excessive vacuum pressure within the submerged
intake of the water circulation system; and decreasing the
excessive vacuum pressure within the submerged intake by
interrupting the power applied to the pump, whereby decreasing the
excessive vacuum pressure within the submerged suction outlet
fitting releases the trapped bather from the suction at the
submerged suction outlet fitting.
15. The method of claim 14, wherein identifying an occurrence of an
excessive vacuum pressure occurs automatically and remotely from
the submerged suction outlet fitting at a control device having at
least one processor.
16. The method of claim 14, wherein decreasing the excessive vacuum
pressure within the submerged intake occurs without introducing air
to the water circulation system.
17. The method of claim 14, further comprising: displaying an
actual water flow-rate of water in the water circulation system at
a control device.
18. The method of claim 18 wherein the actual real-time flow-rate
of the water within the water circulation system is displayed in
real-time.
19. A computer-readable medium encoded with instructions executable
by a processor for a method to automatically release a bather
suction entrapped within an aquatic vessel having a water
circulation system, the trapped bather being held by a suction at a
submerged suction outlet fitting of the water circulation system,
the method comprising: circulating water in the water circulation
system with a pump powered by an electric motor, the water
circulation system having a normal operating range defined by a
minimum allowable flow-rate and a maximum allowable flow-rate;
identifying an occurrence of an excessive vacuum pressure within
the submerged suction outlet fitting of the water circulation
system; and decreasing the excessive vacuum pressure within the
submerged intake by interrupting the power applied to the pump,
whereby decreasing the excessive vacuum pressure within the
submerged intake releases the trapped bather from the suction at
the submerged suction outlet fitting.
20. The method of claim 19, wherein identifying an occurrence of an
excessive vacuum pressure occurs automatically and remotely from
the submerged intake at a control device having the processor.
21. The method of claim 19, further comprising: displaying an
actual water flow-rate of water within the water circulation system
at a control device.
22. The method of claim 21 wherein the actual flow-rate of water
within the water circulation system is displayed in real-time.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims priority to U.S. Provisional
No. 61/386,713 entitled "FLOW RATE ACTIVATED SAFETY VACUUM RELEASE
SYSTEM", naming Joseph D. Cohen as inventor and filed on Sep. 27,
2010, the entirety of which is hereby incorporated by reference and
U.S. Provisional No. 61/525,339 entitled "FLOW RATE ACTIVATED
SAFETY VACUUM RELEASE SYSTEM", naming Joseph D. Cohen as inventor
and filed on Aug. 19, 2011, the entirety of which is hereby
incorporated by reference
FIELD OF THE DISCLOSURE
[0002] The present disclosure relates to a safety vacuum release
system ("SVRS") for use with suction entrapment events in aquatic
facilities. More specifically, the disclosure relates to the
detection of an underload condition in a swimming pool circulation
pump motor and a responsive shutdown of the pump motor. In
addition, the present disclosure relates to suction entrapment
safety vacuum release systems for use with aquatic facilities which
monitors the actual flow-rate of water in the circulation system
and responds to abnormally low flow-rates indicative of a suction
entrapment condition.
BACKGROUND
[0003] Swimming pools and other aquatic facilities typically
require a circulation system to remove water, filter the water,
optionally heat the water, and return the processed water to the
facility. A circulation pump draws water from the facility by
generating a vacuum or a region of negative pressure and pumps the
water back to the facility under positive pressure. Typically, the
circulation pump produces considerable negative pressure through
various intake pipes connected to suction outlet fittings within
the pool.
[0004] Two types of prior art SVRS have been developed and
commercialized. One type reacts to the increase in the vacuum
pressure, which is a potentially lethal force capable of holding a
bather against an intake of the water circulation system, and then
reduces the vacuum level by either injecting fluid or gas (water or
air) at atmosphere pressure into portions of the circulation system
piping, or shutting off the circulation pump, or both. The normal
operating vacuum pressure level of swimming pool pumps varies from
pool to pool and is affected by a number of factors. These factors
include the diametric size of the piping, length of the intake pipe
run, the elevation of the pump in relation to the pool water level,
the overall hydraulic resistance of the circulation system, the
pool operation being performed, and the horsepower of the pump.
Therefore, the critical life-saving function of these SVRS is
dependent upon the correct site specific calibration of the SVRS.
Therefore prior art SVRS may be subject to fail, should it not be
properly calibrated.
[0005] Undesirably, normal operating conditions of a swimming pool,
including those conditions found in the operation of manual and/or
automatic vacuum systems, as well as impeded water circulation
through debris laden skimmers and drain grates, can cause an
increase in vacuum pressure that will undesirably trigger some
existing SVRS when there actually is no flow stoppage or potential
suction entrapment accident.
[0006] A second type of commercially available SVRS reacts to the
load factor change of the electric motor which powers the
circulation pump. The load factor of the circulation pump motor is
most commonly measured as the power factor of the motor, which may
be defined as the percentage of power being converted into energy
divided by the amount of power consumed. Motor load can also be
measured by motor voltage, amperage, or shaft speed measured as
revolutions per minute ("RPM"). The load factor of a circulation
pump motor is directly related to the rate of fluid flow through
the pump. When the water flow is blocked within the swimming pool,
the circulation pump motor may experience an underload condition,
that is, the motor power factor decreases and the shaft RPM
increases. With this second type of SVRS, the underload condition
triggers a shutdown of the circulation pump as a safety release
mechanism.
[0007] This second type of SVRS has three major drawbacks. First,
this type of SVRS has a narrow operating range of water flow-rate;
second, the SVRS has an undesirable time delay for an underload
condition to manifest after a water flow blockage has occurred.
Third, this type of SVRS generally does not operate well when the
pump is installed below the swimming pool water level.
[0008] More specifically, the load on the circulation pump motor
decreases approximately 13% when the water circulation system
changes from normal water flow conditions to a blocked intake flow
condition. Setting the load-sensor to shut off the motor when the
load drops by this small amount only allows for a narrow operating
range of water flow from normal water flow conditions to minus 30%.
Typically, a 1 HP swimming pool filter system operates at 65 GPM.
With this type of SVRS, the pump will shut off when the flow drops
below 45 GPM. Manual or automatic vacuums, in-floor cleaner
systems, or operating with a dirty filter or debris laden skimmer
baskets and drain grates will impede the flow of water to less than
45 GPM and cause this type of SVRS to become a nuisance and shut
the pump off when no hazard exists. Both types of the
aforementioned SVRS have inherent problems with flooded intake
circulation pumps, or pumps installed below the water level of the
swimming pool which they are serving.
[0009] Therefore, it is desirable to employ load-sensing technology
or flow-rate sensing technology as an accurate and responsive
technique for determining occurrence of an aquatic suction
entrapment event. There exists a need for an effective SVRS that
requires substantially no additions in order to retrofit an
existing circulation system.
[0010] Therefore, it is desirable to employ load-sensing technology
or flow-rate sensing technology as an accurate and responsive
technique for determining occurrence of an aquatic suction
entrapment event.
SUMMARY OF THE DISCLOSURE
[0011] The present disclosure generally relates to a safety vacuum
release system ("SVRS") that can be used to retrofit substantially
any swimming pool circulation system by the direct substitution of
the circulation pump motor or the inclusion of a flow-rate sensor,
thereby requiring substantially no expansion of equipment space,
housings, and the like.
[0012] In one embodiment, an aquatic facility with a safety vacuum
release system includes an aquatic vessel configured to contain a
body of water suitable for bathing. The aquatic facility also has a
circulation system for circulating the body of water that includes
at least one circulation intake, a circulation pump that includes a
pump intake in fluid communication with the circulation intake and
a pump output in fluid communication with a circulation output for
directing the water back into the aquatic vessel, and an electric
motor for operating the circulation pump. The aquatic facility also
includes a flow-rate sensor in fluid communication with the
circulation system to measure the rate of flow of the water
circulated by the circulation system (gallons per minute). The
safety vacuum release system is in communication with the
circulation system and the flow-rate sensor. The safety vacuum
release system interrupts the operation of the circulation pump in
response to a particular flow-rate measured by the flow-rate
sensor, pre-determined to be low enough to be caused by a blockage
at a suction outlet fitting.
[0013] In another embodiment, a flow-rate activated safety vacuum
release system includes a circulation system for an aquatic vessel
and a flow-rate sensor operably engaged to the circulation system.
The flow-rate sensor is configured to determine a rate of flow
through the circulation system. The flow-rate activated safety
vacuum release system also includes a control system in
communication with the flow-rate sensor configured to receive a
signal related to the flow-rate through the circulation system. The
control system also provides one or more control signals to a pump
of the circulation system.
[0014] A method for automatically releasing a bather suction
entrapped in an aquatic vessel having a water circulation system is
disclosed herein. The method may be used to free the trapped bather
being held by suction at a submerged suction outlet fitting of the
water circulation system. The method includes circulating water in
the water circulation system with a pump powered by a motor. The
water circulation system has a normal operating range defined by a
minimum allowable flow-rate and a maximum allowable flow-rate. The
method also includes identifying an occurrence of an excessive
vacuum pressure within the submerged intake of the water
circulation system, decreasing the excessive vacuum pressure within
the submerged suction outlet fitting by interrupting the power
applied to the pump, and releasing the trapped bather from the
submerged intake.
[0015] In various other embodiments, the systems and methods
disclosed herein may be encoded on computer-readable media that may
be executed by a processor. An additional aspect of the present
disclosure is to provide an SVRS that protects the pump against
damage that can result from running dry. Correspondingly, this SVRS
maintains the continuity of the water content of the circulation
system and does not introduce air into the circulation system.
Similarly, this SVRS does not cause the pump to lose prime, thereby
enabling the circulation system to restart with minimum
difficulty.
[0016] Another aspect is to provide an SVRS that requires no
hydraulic connections to the fluid circulation system of the
swimming pool. Unique to this disclosure is that this SVRS is
non-invasive because it is not in direct fluid communication with
the circulation system and requires no hydraulic connections.
Connections like pressure sensor lines, reversing valves, and
pressure relief valves are not needed with this disclosure.
[0017] A further aspect of the present disclosure to enable the
efficient and economical design or upgrade of pool circulation
systems by the suitable selection of a motor equipped with
load-sensor. The relatively simple selection or exchange of a motor
is far more economical that installing supplemental piping, valves,
and like bulky equipment previously required.
[0018] Another aspect of the present disclosure is to provide an
SVRS that can be completely built into and incorporated within a
swimming pool pump motor. A similar aspect is to provide an SVRS
that can be retrofitted to a swimming pool simply by changing out a
circulation pump motor, which is a relatively standard maintenance
procedure for any pool.
[0019] One aspect is to provide a readily available and easily
implemented solution to suction entrapment, which swimming pool
pump manufacturers can incorporate into their pumps with little
burden on established practices. An additional aspect is to provide
an SVRS that is likely to be of exceptionally low cost, thus
enabling a greatly increased range of pool owners to improve the
safety of their pools by outfitting the pools with an SVRS. Another
aspect is to expand the scope of applications for water flow-rate
sensing technology to include this new application as a life saving
device for swimming pools.
[0020] According to one aspect of the disclosure, an aquatic
facility is equipped with a safety vacuum release system that
detects underload of the motor powering the circulation pump. The
facility provides an aquatic vessel that contains a body of water
having at least one circulation suction outlet fitting (drain) near
a bottom of the aquatic vessel. A circulation pump has an intake
side for drawing water out of the aquatic vessel and an output side
for directing water back into the aquatic vessel. A suction line
interconnects the suction outlet fitting and the intake side of
said circulation pump, and a return line interconnects the vessel
and the outlet side of the circulation pump. An electric motor
operates the circulation pump when said motor operates and shuts
off the pump when the motor is shut off. A suitable flow-rate
sensor device connected to the suction line may measure a flow-rate
outside of a predetermined operating range indicative of a blockage
at the suction line, and the safety vacuum release system controls
a switch upon the detection of the undesired flow-rate to shut off
the motor.
[0021] Another aspect of the disclosure provides a method of
detecting a suction entrapped blockage at a suction outlet fitting
supplying the intake side of a circulation pump with water flow of
an aquatic facility and releasing the blockage. The method steps
include powering the circulation pump by an electric motor; sensing
a flow-rate change indicative of a blockage held by vacuum at a
suction outlet fitting; shutting off the electric motor in response
to detection of the flow-rate change, and releasing the blockage at
the suction outlet fitting by retaining the motor in shut-off
status for a time sufficient to allow the vacuum to neutralize.
[0022] In one aspect, the present disclosure provides an SVRS for
an aquatic facility which monitors and reacts directly to changes
in the flow-rate of the water passing through the aquatic facility
water circulation pump. In another aspect, the present disclosure
provides an SVRS for an aquatic facility which will both reliably
and quickly release suction entrapped bathers by shutting off the
water circulation pump motor without delay. Yet another aspect of
the present disclosure is to shut down the water circulation pump
and provide release for a potential suction entrapment incident
before a complete blockage occurs.
[0023] A further aspect of the present disclosure provides an
aquatic facility operator with a real-time readout of the actual
rate of flow of the water through the water circulation pump
system. Another aspect of the present disclosure provides an SVRS
which will function reliably on all pool circulation pumps
regardless of their elevation in relation to the pool water
level.
[0024] Yet another aspect of the present disclosure provides an
SVRS which will function reliably in all types of flooded suction
pump installations independently of the pump's relationship to the
aquatic facility water level. A further aspect of the present
disclosure provides an SVRS which is operable over a wide range of
water flow-rates for an aquatic facility water circulation pump
system to permit an aquatic facility operator to perform normal
facility maintenance operations without problematic pump shutdowns
often caused by prior art SVRS.
[0025] These and other aspects, advantages and novel features of
the present disclosure will become apparent from the following
description of the disclosure when considered in conjunction with
the supplemental materials provided in support thereof.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] FIG. 1 is a schematic diagram of a swimming pool with SVRS
built into the water circulation system according to one
embodiment.
[0027] FIG. 2 is a block diagram of a motor system including a
load-sensor according to one embodiment.
[0028] FIG. 3 is a schematic diagram of a flow-rate activated SVRS
according to one embodiment.
[0029] FIG. 4 is a block diagram of a computing device for
operating the SVRS according to one embodiment.
DETAILED DESCRIPTION
[0030] The present disclosure relates to is a safety vacuum release
system ("SVRS"). An SVRS is an automatic safety system in an
aquatic facility such as a swimming pool, spa, wading pool, or like
aquatic vessel that in use contains a body of water. Such a system
automatically releases a blocking object that blocks a
single-sourced circulation pump. Typically, the blockage is a
bather who has become trapped onto a suction outlet fitting, which
typically communicates through a suction conduit with a circulation
pump. Via the conduit, the circulation pump typically found in an
aquatic facility is capable of producing a dangerously high vacuum
level at a suction outlet fitting if intake flow to the pump is
blocked. The level of suction can be high enough that a bather
cannot free himself from a suction outlet fitting unless released
by a SVRS. Suction entrapment can drown or otherwise injure a
trapped bather unless the victim is quickly released.
[0031] Circulation systems are present in substantially all aquatic
facilities. Such systems are necessary for filtration,
sanitization, heating, hydrotherapy, and the operation of water
features such as decorative fountains. A circulation pump provides
the water flow within these circulation systems. An electric motor
is connected to the pump to provide motive power.
[0032] The disclosure relates to systems and methods of sensing and
responding to blockage or bather entrapment at suction outlet
fittings. Various embodiments of the present disclosure relate to
the systems and methods disclosed in co-owned U.S. patent
application Ser. No. 11/163,860, entitled "Load Sensor Safety
Vacuum Release System," the contents of which are incorporated
herein by reference in its entirety.
[0033] In various embodiments, load-sensing systems monitor the
operation of an electric pump motor and determine the power level
that the motor is producing. These systems detect overload and
underload conditions. Such systems can shut off the motor in
response to sensing an undesirable overload or underload condition.
The intended purpose of these systems is to protect against damage
to the motor or to an associated, powered machine or the product
being produced by the machine. Such systems also can prevent waste
of electrical power
[0034] Load-sensing systems such as those referred to, above, have
been used to monitor the electrical power factor of a motor. It has
now been discovered that when a motor controlled by a load-sensor
is connected to operate a circulation pump such as those used in
swimming pools and the like, the load-sensor can operate in a new
way as an SVRS. Despite the fact that the pump remains charged with
water during a vacuum entrapment event, the motor changes shaft
speed in a manner that the load-sensor detects. Shaft speed
increases as load is reduced. Thus, the load-sensor becomes a
monitor for motor shaft speed (RPM).
[0035] Suitable load-sensors are generally disclosed by U.S. Pat.
No. 4,123,792 to Gephart et al., issued Oct. 31, 1978, U.S. Pat.
No. 4,419,625 to Bejot et al., issued Dec. 6, 1983, U.S. Pat. No.
5,473,497 to Beatty issued Dec. 5, 1995, and U.S. Reissue Pat. RE
33,874 to Miller issued Apr. 7, 1992. Each of these patents is
incorporated by reference herein for disclosure of load-sensor
technology.
[0036] A load-sensor measures the power factor of a motor. The
load-sensor output can produce an accurate reading of the
percentage of the electrical current passing through the motor that
is converted into useful load or power that is transferred to the
attached circulation pump. Load-sensors are commercially produced
as stand alone components that can be attached to any motor. In
addition, some motors include an integrated load-sensor.
Particularly the latter allows the substitution of a motor with
integral load-sensor into a space that previously housed a motor
without load-sensor.
[0037] During an aquatic suction entrapment event, a trapped bather
or other blockage stops water flow into a suction outlet fitting of
an aquatic facility. Typically, in order for suction entrapment to
occur, the circulation pump must have become single-sourced to a
single suction outlet fitting, such that the pump receives all
intake of water from the single fitting. When the blockage closes
off the final suction outlet fitting, vacuum or negative pressure
abruptly increases within the intake pipe to the circulation pump.
The high level of vacuum is communicated from the pump to the
victim through the conduit that connects the pump to the blocked
suction outlet fitting inside of the swimming pool.
[0038] Simultaneously with the entrapment event, water flow within
the circulation system abruptly decreases or stops. As a result,
the pump is moving a substantially decreased volume of water.
Correspondingly, the electric pump motor sees an abruptly decreased
load accompanied by a corresponding increase in RPM. The
load-sensor on the pump motor senses the aquatic suction entrapment
event by detecting the abruptly decreased load factor for the
electric motor that drives the circulation pump. This method of
operating an SVRS eliminates the need to monitor vacuum level for
the intake line.
[0039] The load-sensor is configured to shut off the circulation
pump motor upon detecting a predetermined level of motor underload
condition. Extensive testing has established that a motor underload
condition will result as a reliable indication of a flow blockage
at the pump intake that is severe enough to be unsafe for bathers.
Thus, a load-sensor controlling a motor and monitoring underload
condition will perform as an SVRS that, in the event a bather has
become trapped, shuts off the motor and hence the circulation pump.
With the circulation pump stopped, the resulting dangerously high
level of vacuum quickly neutralizes. By the use of normal controls,
the motor and load-sensor can be configured to require either a
manual reset or automatic reset after a predetermined amount of
time, such as five minutes, has elapsed since the load-sensor shut
off the motor.
[0040] In one embodiment of the disclosure, a load-sensor is
integrated within the circulation pump motor at the time of
manufacture. Such a motor can be easily and universally fit into
any swimming pool, because all swimming pools have a circulation
pump motor.
[0041] This SVRS load-sensor is specifically adjusted to shut off
the motor in an underload situation. Extensive testing has shown
that underload is indicative of a characteristic loss of water flow
and motor RPM increase that accompanies a suction entrapment event.
Further, the load-sensor must be adjusted to reliably pass official
standards for SVRS devices. Testing standards bodies such as ASTM
or ANSI establish a standard for SVRS performance without failure.
These standards provide the official protocol for testing an SVRS
in order to gain ASTM or ANSI approval. The procedure calls for
testing the SVRS in a variety of hydraulic situations. Water is
supplied to a test pump from a single, standard, eight-inch aquatic
suction outlet fitting. With the test pump in operation, a blocking
element with fifteen pounds of buoyancy is repeatedly placed over
the suction outlet fitting to simulate a series of suction
entrapment events. The SVRS must successfully release the blocking
element within 3 seconds to 4.5 seconds (depending on the length of
pipe) in each and all of the tests without failure.
[0042] When a suction entrapment event occurs, a bather has blocked
the water flow into a suction outlet fitting within a swimming
pool, stopping flow to the circulation pump. The stoppage of water
flow causes the pump to create an extremely high level of vacuum at
the pump intake. This high level of vacuum is transmitted through
the stationary water within the suction pipe to the suction outlet
fitting, where the victim has become trapped. Typically, any
standard swimming pool pump, regardless of the horsepower rating of
the pump motor, will create in excess of twenty-four in HgR (inches
of mercury relative) (.about.11.8 psi) vacuum when the pump intake
is blocked. Every square inch of area of adhesion between the
fitting and the victim has an adhesion force of over eleven pounds.
This vacuum or negative pressure, rather than the loss of water
flow, is the lethal force that can cause an accident such as injury
or drowning death to a bather.
[0043] When a suction entrapment event occurs, the vacuum level
increases and the flow of water decreases within the suction pipe.
The vacuum level is inversely proportional to the flow of water.
The load or power transferred by the electric motor to the pump is
directly proportional to the flow of water but not to the vacuum
level nor to the relative fluid pressure within the circulation
system. The SVRS senses the load, which is fundamentally determined
by the volume of water flowing through the pump. Therefore, when a
bather is trapped, and in contrast to prior art SVRS, this SVRS
reacts to the loss of water flow rather than to an increase in
vacuum level. The disclosure includes this new method for operating
an SVRS.
[0044] In one embodiment, the SVRS operates to detect a suction
entrapment event by sensing the percentage of electrical power
being consumed by the pump motor. The load-sensor converts this
sensed value to load or power factor. In an SVRS with programmable
operation, a shut off setting typically in the range from 55% to
62% has been found suitable and appropriate. If suction flow
blockage occurs, the water flow to the pump is interrupted or
greatly restricted. The electric pump motor is underloaded. In this
situation, the load-sensor senses the underload condition and shuts
off the pump motor. As a result, the high vacuum level created by
the operating pump, accompanying the flow blockage, neutralizes,
thereby releasing the victim.
[0045] A novel aspect of the disclosure is that the SVRS reacts to
hydraulic situations within the pump without having any direct
fluid communication with the water flow path.
[0046] With reference to FIG. 1, an aquatic facility or vessel such
as a swimming pool 10 includes a water circulation system 1. A
specially configured circulation pump 12 operates this system.
Normally the pump 12 is a centrifugal pump. One or more conduits or
suction lines such as pipelines 14 are connected for communication
between the pool and the intake side of pump 12, such that the pump
12 draws water through pipelines 14. Various suction outlet
fittings at the pool provide water into the pipelines 14.
[0047] For example, a skimmer 16 provides water from the typical
water surface level 17 when the pool is full. A skimmer includes a
basket 18 for catching floating debris from the pool surface. A
weir 20 helps to retain the debris in the skimmer. Below the
basket, a float valve 22 controls the skimmer, and a section
equalizer line 24 connects the bottom of the skimmer back to the
pool.
[0048] A circulation drain 26 on the bottom of the pool provides
water to the pump 12. A second drain 28 is beneficial for safety
reasons, to help avoid suction entrapment that could be caused by a
single-source pump intake. Pool drains 26, 28 should include
suction outlet safety covers 30.
[0049] The circulation system 1 directs water flow through a
circuit. Suction valve manifolds 32 between the pool and the intake
side of the pump control incoming flow. The outlet side of the pump
feeds water to a filter 34. In turn, water flows from the filter to
an optional heater 36. In some circulation systems 1, a check valve
38 might be installed between the heater 36 and filter 34 to
prevent reverse flow of heated water into the filter. Check valves
38 should be removed to better allow vacuum level to neutralize
quickly when the pump motor stops. After passing through the filter
and heater, the water flows back into the pool through a return
line 40.
[0050] Suction entrapment can occur if the pump 12 becomes
single-sourced, drawing all of its water from one suction outlet
fitting, such as at a single drain 26. A pump can become
single-sourced by a variety of circumstances. For example, a
skimmer 16 sometimes is installed without an equalizer line 24. The
omission of the equalizer line 24 allows a plugged basket 18 to
block the skimmer 16. Similarly, a low water level 42 or a jammed
weir 20 can close the float valve 22. In any of these
circumstances, the skimmer 16 ceases to perform as a water source
to pump 12 and contributes to the possibility that the pump will
become single-sourced.
[0051] A variety of other events can result in the pump 12 becoming
single-sourced or otherwise contribute to a suction entrapment
event. Dual drains 26, 28 can provide a measure of safety against
the pump becoming single-sourced. However, if two bathers
simultaneously block the dual drains, entrapment can occur. Pool
control valves such as suction valve manifolds 32 accidentally can
be set for single-sourced operation. In circulation systems 1 where
check valve 38 has not yet been removed, the check valve can
interfere with the operation of an SVRS by maintaining the high
vacuum even after the pump motor is shut off. Consequently, check
valves 38 should be removed from a circulation system 1. Missing
suction outlet safety covers 30 also can contribute to the
likelihood of a suction entrapment event.
[0052] If a bather should block the single-source fitting, an
entrapment accident can result. Swimming pool pumps can be quite
powerful as compared to pumps used only a few decades ago, causing
an increased risk of suction entrapment. A standard eight-inch
drain cover, if single-sourced to a one horsepower pump, can
produce three hundred fifty pounds of entrapment force. A
twelve-inch drain cover can transmit over sixteen hundred pounds of
adhesion force to an entrapped victim.
[0053] An electric motor 44 powers the circulation pump 12. Motor
44 typically is connected to a power source 46, such as an AC power
grid, for example, to draw line voltage and current. A load-sensor
48 operates to detect underload and to shut off the motor when
underload is detected. The load-sensor 48 controls a switch 50 that
shuts off the motor from the AC grid. Motors with built-in
load-sensors are produced by various commercial sources.
[0054] As an example of a modern, commercial load-sensor, the block
diagram of FIG. 2 shows a motor system 44 of impedance 52 in
combination with a load-sensor system 48 suitable to shut off the
electric motor system upon detecting a suitable underload. The
load-sensor 48 detects motor underload when coupled to reference
levels. The load-sensor 48 develops first and second electrical
signals indicative of first and second parameters of power
delivered to the load, pulse width modulates the first electrical
signal to produce a pulse width modulated first electrical signal,
and modulates the second electrical signal in accordance with the
pulse width modulated first electrical signal to produce a power
waveform. The load-sensor 48 then integrates the power waveform to
produce an output signal indicative of the energy delivered by the
motor 44 to the load.
[0055] Pulse width modulator 54 senses the line voltage appearing
across the impedance 52 and produces a voltage signal that is a
pulse width modulated version of the line voltage. This pulse width
modulated voltage signal is developed at a pulse width modulator
output 56. The AC line voltage is modulated by the pulse width
modulator 54 during each of either the positive half-cycles or
negative half-cycles of the line voltage so that the pulse width
modulated voltage signal comprises a set of pulses at times
corresponding to each of either the positive half-cycles or
negative half-cycles and a value of zero at times corresponding to
the other of the positive half-cycles or negative half-cycles.
[0056] A current sensor 58 detects the line current that flows
through the motor 44 and delivers a current signal indicative of
line current to a switch 60. The switch 60 modulates the current
signal and is controlled in accordance with the pulse width
modulated voltage signal produced by the pulse width modulator 54
at the pulse width modulator output 56 such that the switch 60 is
closed during each pulse of the pulse width modulated voltage
signal and is open at all other times. In this manner, the switch
60 effectively multiplies the voltage appearing across the motor
impedance 52 with the current flowing through the motor 44 during
every other half-cycle of the line voltage to produce a modulated
current signal indicative of the real power delivered by the power
source 46 to the motor 44.
[0057] An integrator 62 integrates the modulated current signal
developed by the switch 60 to produce an energy waveform that is
indicative of the energy delivered to the motor 44 during each
positive half-cycle or negative half-cycle of the line voltage and,
therefore, that is indicative of the energy delivered by the motor
44 to pump 12. The energy waveform developed by the integrator 62
is delivered to a switch controller 64 that latches the final value
of the energy waveform in response to a signal developed, for
example, on a line 66, and compares the latched value with a
predetermined level to detect a motor underload condition. If the
amplitude of the energy waveform is below a predetermined reference
level, an underload condition is detected and the switch controller
64 opens the switch 50 to disconnect the power source 46 from the
motor 44. In this manner, the motor 44 provides the function of an
SVRS during a suitable underload condition.
[0058] The integrator 62 is reset by a microprocessor 70 in
conjunction with a switch 72. The microprocessor 70, which
inherently contains or enables a clock function or timing means,
counts the cycles of the line voltage appearing across the
impedance and produces a reset signal after a predetermined number
of line cycles. The reset signal closes the switch 72 in order to
reset the integrator 62 and thereby to reset the energy waveform to
a value of zero. The microprocessor 70 can reset the integrator 62
every half-cycle so that the integrator 62 produces an energy
waveform indicative of the energy delivered to the motor 44 during
any particular line voltage half-cycle or, alternatively, the
microprocessor 70 can reset the integrator 62 after a predetermined
number of line cycles. The latter configuration enables the
integrator 62 to integrate the modulated current signal produced by
the switch 60 over a number of consecutive line cycles, enabling
the load-sensor 48 to measure comparatively small amounts of energy
over a number of line cycles to produce an accurate indication of
the motor loading condition. The microprocessor 70 produces a
latching signal on the line 66 prior to resetting the switch 72.
The latching signal enables the switch controller 64 to latch the
energy waveform produced by the integrator 62.
[0059] Alternatively, the operation of the switch controller 64 can
be performed by the microprocessor 70. In this alternative, the
output of the integrator 62 is converted into a digital signal by
an ND converter (not shown). The digital signal is provided to the
microprocessor 70, which determines whether an underload condition
exists by comparing the signal with a reference load value. In this
alternative, the microprocessor 70 directly controls the switch 50
in order to disconnect power from the motor 44 when an underload
condition occurs.
[0060] In load-sensors using a microprocessor 70, programming
readily sets the shut off period of the switch controller 64. For
use as an SVRS, the programming should call for a predetermined
shut off period on the order of five minutes. This period provides
adequate time to an entrapped bather to recover and remove himself
from the suction outlet fitting. Thus, it is adequate and
acceptable for the circulation pump motor to restart automatically
after a five-minute shut off cycle. The microprocessor 70 can
monitor the shut off period by use of its contained timing
function. After the predetermined period, the microprocessor can
signal the switch controller 64 to close switch 50 and thereby
restart the pump motor 12.
[0061] The present disclosure also relates to an SVRS for an
aquatic facility which incorporates an electronic flow-rate
indicator operatively connected to a circulation system of an
aquatic facility. A flow-rate activated SVRS functions
substantially similar to the load-sensing SVRS described above. The
flow-rate activated SVRS, however, relies upon the measured
flow-rate of the water within the circulation system 1 to identify
and remedy a suction entrapment event. By way of example and not
limitation, a flow-rate activated SVRS continuously measures the
rate of flow of water within the circulation system 1. If the
flow-rate activated SVRS measures a flow-rate that falls outside of
a normal operating range, thereby indicating an abnormal blockage
at an intake, the system interrupts the power supplied to the
circulation pump in order to stop the pump to break the vacuum at
the intake.
[0062] FIG. 3 is a schematic diagram of a flow-rate activated SVRS
100 according to one embodiment. The flow-rate activated SVRS 100
includes a control device 102 that is in communication with a
flow-rate sensor 104, a pool circulation pump 12, a computing
device 200, and a power source 46. In addition, the control device
could include optionally a pump and heater time clock to set daily
swimming pool filtration cycles. In one embodiment, the computing
device 200 is incorporated into the control device 102. In one
embodiment, the system shown in FIG. 3 may be incorporated into the
aquatic system of FIG. 1. For example, the flow-rate sensor 104 may
be incorporated between the pool circulation pump 12 and the filter
34 of FIG. 1. Thus, in this embodiment, the flow-rate activated
SVRS works in conjunction with the load-sensor SVRS described
above. In alternate embodiments, the flow-rate SVRS may provide the
safety measures described without the load-sensor.
[0063] In various embodiments, the control device 102 may also
include a display device 106 and an input device 108 and may be
located remotely from the circulation system 1. The display device
106 may be an LCD display that is incorporated in to the control
device 102. In other embodiments, the display device 106 may be
external to the control device 102 and may be any display device
suitable for displaying data. The input device 108 may be as a
keyboard or a pointing device (e.g., a mouse, trackball, pen, or
touch pad), for receiving input at the control device 102. One or
both of the display device 106 and the input device 108 may be
incorporated in to the control device 102. Alternately, one or both
of the display device 106 and the input device 108 may external to
but in communication with the control device 102.
[0064] The flow-rate sensor 104 measures the flow-rate of water
traveling through the circulation system 1 of the aquatic facility.
The flow-rate sensor 104 may also measure the velocity of water
traveling through the circulation system 1. The flow-rate sensor
104 can be attached to the circulation system 1 of the aquatic
facility such that the sensor is non-invasive to the circulation
system 1. For example, the flow-rate sensor 104 may be clamped onto
a pipe of the circulation system. In various embodiments, the
flow-rate sensor 104 may be connected to a discharge pipe 110 of
the circulation pump. In general, however, the flow-rate sensor 104
may be incorporated anywhere along the circulation system 1 to
measure the rate of flow of water through the system.
[0065] A number of commercially available off the shelf electronic
flow-rate sensors may be employed in accordance with the teachings
as herein set forth including, a Doppler Ultrasonic Flow Meter and
a Transit Time Ultrasonic Flow Meter, both manufactured by
Dynasonics of Racine Federated Inc., of Racine, Wis. and Shenitech
LLC of Woburn, Mass. By way of illustration and not by limitation,
other types of flow-rate sensors including, magnetic paddlewheel,
vortex shedding, turbine, deflector, ultrasonic transit time,
ultrasonic Doppler, and differential pressure sensors may be used.
In a preferred embodiment, an ultrasonic transit time flow-sensor
would be employed, inasmuch as ultrasonic flow-sensors are
accurate, dependable, and non-invasive (e.g. installed by clamping
onto the discharge pipe 110 without coming into contact with the
water).
[0066] In one example, a Doppler-ultrasonic flow meter or a transit
time ultrasonic flow meter is attached to the outside surface of
the pump discharge pipe 110 of the circulation pump 12 of the
aquatic facility to measure the flow-rate through the pipe
non-invasively. This arrangement allows the flow-rate to be
determined without direct interference in the circulation system 1.
Moreover, the flow-rate sensor 104 may be attached easily and at
little cost, by using an injection-molded plastic clip that snaps
onto the discharge pipe 110. In addition, because the flow-rate
sensor 104 provides the actual water flow-rate through the
circulation system 1, the cutoff threshold can be set at a level
that reduces the occurrences of false tripping of the switch 50
that disconnects power supplied to the pump motor 44. In one
example, the cutoff threshold may be set at 20-30 gallons per
minute (GPM), which would provide the pump 12 a greater operating
range, thereby reducing the occurrence of inadvertent tripping of
the switch 50 due to the changes in the rate of flow under normal
swimming pool operation.
[0067] The flow-rate sensor 104 is robust in relation to the types
and number of pumps and circulation systems from which the
flow-rate can be measured, as the flow-rate sensor is independent
of vacuum and pressure levels within the circulation system 1. Any
suitable flow-rate sensors, such as the flow-rate sensor 104, may
be used regardless of the pump location relative to the water level
of the aquatic vessel.
[0068] The flow-rate activated SVRS 100 may further incorporate a
delay mechanism (not shown) that allows the pump 12 to be restarted
after a high vacuum level has been detected and the pump has been
shut off. In one embodiment, a timer (not shown) may disable the
pump shut-off response for a specified amount of time when the pump
is first powered up. For example, the delay may disable the shut
off mechanism while the pump primes and accelerates water to a
stable flow-rate. In one embodiment, the delay mechanism and/or
timer may be incorporated into the control device 102. The system
100 may also verify that the flow through the circulation system 1
has exceeded the cut-off level and then initiates the safety vacuum
release feature to reduce the vacuum pressure level in the event a
slow blockage occurs. Additionally, an automatic restart feature
may be incorporated into the system that attempts to restart the
system a specified amount of time after the safety vacuum release
feature has been activated. This automatic restart feature may
prevent the water from stagnating in a situation where the pump has
been shut off by the SVRS.
[0069] In operation, the computing device 200 may execute one or
more software programs and/or applications which determine and
monitor the maximum and minimum flow-rates allowed by the
circulation system 1. In addition, the computing device may read a
computer-readable medium encoded with instructions, one or more
software programs, or applications to determine and monitor the
maximum and minimum flow-rates allowed by the circulation system 1.
Data regarding the maximum and minimum flow-rate limits may be
stored within memory 216 of the computing device 200. If the
real-time flow-rate exceeds either of these limits, the control
device 102 interrupts the power from the power source 46 by
generating a signal or opening a relay to the pump motor 44 to stop
the operation of the pump 12. In one embodiment, the computing
device 200 is preprogrammed, such that the only on-site programming
required would be to indicate the nominal pipe diameters for the
circulation system 1. By way of example and not limitation, the
circulation system may use pipes having nominal diameters of
1.25'', 1.5'', 2.0'', 2.5'', 3.0'', or 4.0''.
[0070] In one embodiment, the control device 102 receives the
signals from the flow-rate sensor and displays the water flow-rate,
in real-time, on the display device 106; although other means of
displaying flow-rate may be used without departing from the scope
of the present disclosure. In another embodiment, the computing
device 200, as shown in FIG. 4, receives and processes data from
the flow-rate sensor 104. The computing device 200 also transmits
data from the flow-rate sensor 104 in real-time to the display
device 106.
[0071] Alternately, the control device 102 could be programmed to
provide the pool operator with a real-time turnover rate. In
general, the turnover rate is the amount of time, typically
expressed in hours, for the total volume of the swimming pool 10 to
pass through the filter 34. The computing device 200 may be
programmed with data related to pool volume, and then the control
device 102 may display the real-time turnover rate in hours. The
computing device 200 may also be programmed to provide the
real-time percentage of clean filter flow. Therefore, the control
device 102 may then display what percentage of the current
flow-rate is equal to the clean flow-rate.
[0072] Other features may also be programmed or otherwise included
in the flow-rate activated SVRS 100. For example, as described
above, the control device 102 may be configured to provide an
indication of a dirty filter in the circulation system 1 of the
aquatic vessel. In one embodiment, the dirty filter indicator may
be provided when the flow-rate of the circulation system 1 has
dropped to 50% of clean filter flow-rate. In another example, the
control device 102 may be programmed to control the pump 12 to
maintain an optimum flow-rate through the circulation system 1 by
gradually increasing the pump speed as hydraulic resistance to the
flow is increased due to a dirty filter. In yet another example,
the control system may include a freeze preventer feature that
would activate the pump to circulate water through the system in
the event that the ambient air temperature drops below a specified
temperature. For example, in one embodiment, the control system may
activate the pump when the ambient air temperature drops below 40
degrees F. to prevent freeze damage to the circulation system
1.
[0073] The methods and operations of the flow-rate activated SVRS
100 described herein may be performed by the control device 102
that includes or is at least in communication with the computing
device 200. FIG. 4 is a block diagram of the computing device 200
for operating the flow-rate activated SVRS 100 according to one
embodiment. The computer system (system) includes one or more
processors 202-206. Processors 202-206 may include one or more
internal levels of cache (not shown) and a bus controller or bus
interface unit to direct interaction with the processor bus 212.
Processor bus 212, also known as the host bus or the front side
bus, may be used to couple the processors 202-206 with the system
interface 214. System interface 214 may be connected to the
processor bus 212 to interface other components of the computing
device 200 with the processor bus 212. For example, system
interface 214 may include a memory controller 218 for interfacing a
main memory 216 with the processor bus 212. The main memory 216
typically includes one or more memory cards and a control circuit
(not shown). System interface 214 may also include an input/output
(I/O) interface 220 to interface one or more I/O bridges or I/O
devices with the processor bus 212. One or more I/O controllers
and/or I/O devices may be connected with the I/O bus 226, such as
I/O controller 228 and I/O device 230, as illustrated.
[0074] I/O device 230 may also include an input device (not shown),
such as an alphanumeric input device, including alphanumeric and
other keys for communicating information and/or command selections
to the processors 202-206. Another type of user input device
includes cursor control, such as a mouse, a trackball, or cursor
direction keys for communicating direction information and command
selections to the processors 202-206 and for controlling cursor
movement on the display device.
[0075] The computing device 200 may include a dynamic storage
device, referred to as main memory 216, or a random access memory
(RAM) or other computer-readable devices coupled to the processor
bus 212 for storing information and instructions to be executed by
the processors 202-206. Main memory 216 also may be used for
storing temporary variables or other intermediate information
during execution of instructions by the processors 202-206. The
computing device 200 may include a read only memory (ROM) and/or
other static storage device coupled to the processor bus 212 for
storing static information and instructions for the processors
202-206. The system set forth in FIG. 2 is but one possible example
of a computer system that may employ or be configured in accordance
with aspects of the present disclosure.
[0076] According to one embodiment, the above techniques may be
performed by computing device 200 in response to processor 204
executing one or more sequences of one or more instructions
contained in main memory 216. These instructions may be read into
main memory 216 from another machine-readable medium, such as a
storage device. Execution of the sequences of instructions
contained in main memory 216 may cause processors 202-206 to
perform the process steps described herein. In alternative
embodiments, circuitry may be used in place of or in combination
with the software instructions. Thus, embodiments of the present
disclosure may include both hardware and software components.
[0077] A machine readable medium includes any mechanism for storing
or transmitting information in a form (e.g., software, processing
application) readable by a machine (e.g., a computer). Such media
may take the form of, but is not limited to, non-volatile media and
volatile media. Non-volatile media includes optical or magnetic
disks. Volatile media includes dynamic memory, such as main memory
216. Common forms of machine-readable medium may include, but is
not limited to, magnetic storage medium (e.g., floppy diskette);
optical storage medium (e.g., CD-ROM); magneto-optical storage
medium; read only memory (ROM); random access memory (RAM);
erasable programmable memory (e.g., EPROM and EEPROM); flash
memory; or other types of medium suitable for storing electronic
instructions.
[0078] For the various embodiments, a number of experiments were
conducted to determine the operating range for the SVRS and to
verify the consistency of operation under a variety of conditions.
In one such experiment, a Shenitech.TM. ST301 Transit Time Flow
Meter was used as the flow-rate sensor in an embodiment of the
flow-rate activated SVRS. The SVRS was programmed to shut off the
circulation pump 12 when the water flow in the circulation system 1
dropped below 20 GPM.
[0079] Various combinations of pump horsepower, pump elevation
(relative to the water level of the pool), and line voltages were
tested under conditions where the flow of water gradually decreased
or was abruptly restricted within in-line valves of the pump
suction intakes and the pump discharge pipes. These various
combinations and conditions were chosen to simulate real life
blockages in an aquatic facility. The actual pump shut off points
(in GPM) are presented below in table 1.
TABLE-US-00001 TABLE 1 PUMP ELEVATION TO RESERVOIR WATER LEVEL
Center of Pump Intake to Reservoir WL 24'' Above WL At WL 18''
Below WL 1 HP Pump at 208 V Line Voltage PUMP SUCTION INTAKE
BLOCKAGE 20 GPM 20 GPM 20 GPM PUMP DISCHARGE BLOCKAGE 20 GPM 20 GPM
20 GPM 1 HP Pump at 240 V Line Voltage PUMP SUCTION INTAKE BLOCKAGE
20 GPM 20 GPM 20 GPM PUMP DISCHARGE BLOCKAGE 20 GPM 20 GPM 20 GPM 2
HP Pump at 208 V Line Voltage PUMP SUCTION INTAKE BLOCKAGE 20 GPM
20 GPM 20 GPM PUMP DISCHARGE BLOCKAGE 20 GPM 20 GPM 20 GPM 2 HP
Pump at 208 V Line Voltage PUMP SUCTION INTAKE BLOCKAGE 20 GPM 20
GPM 20 GPM PUMP DISCHARGE BLOCKAGE 20 GPM 20 GPM 20 GPM
[0080] During the experiments, a programmable flow-rate damper was
set at zero (0) seconds to achieve a fast pump shut-off. As shown,
the flow-rate activated SVRS of the present disclosure accurately
shut off the circulation pump when the flow-rate sensor measured a
flow-rate below 20 GPM in all experimental combinations.
[0081] In addition, during the gradual pump discharge blockage
experiments, the circulation pump produced vapor bubbles which
caused the flow-rate sensor to read values approximately 30% above
the actual flow-rates at flow-rates below 35 GPM. Therefore, based
on these experiments various embodiments of the flow-rate activated
SVRS may be programmed according to the power of the circulation
pump as provided in Table 2.
TABLE-US-00002 TABLE 2 PUMP LOW FLOW HORSEPOWER SHUT OFF .75
HP/1-Speed 20 GPM 1.0 HP/1-Speed 22 GPM 1.5 HP/1-Speed 25 GPM 2.0
HP/1-Speed 28 GPM 3.0 HP/1-Speed 30 GPM 3.0 HP/Variable 30 GPM
[0082] The foregoing is considered as illustrative only of the
principles of the disclosure. Further, since numerous modifications
and changes will readily occur to those skilled in the art, it is
not desired to limit the disclosure to the exact construction and
operation shown and described, and accordingly all suitable
modifications and equivalents may be regarded as falling within the
scope of the disclosure.
* * * * *