FLOW-RATE ACTIVATED SAFETY VACUUM RELEASE SYSTEM
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.
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 DISCLOSUREThe 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.
BACKGROUNDSwimming 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.
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.
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.
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.
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.
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.
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.
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 DISCLOSUREThe 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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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
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).
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.
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.
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.
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.
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.
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.
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.
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) (˜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.
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.
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.
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.
With reference to
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.
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.
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.
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.
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.
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.
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.
As an example of a modern, commercial load-sensor, the block diagram of
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.
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.
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.
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.
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.
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.
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.
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.
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.
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).
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.
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.
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.
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″.
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
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.
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.
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.
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.
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
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.
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.
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™ 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.
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.
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.
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.
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.
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.
Type: Application
Filed: Sep 27, 2011
Publication Date: Mar 29, 2012
Inventor: Joseph D. Cohen (Denver, CO)
Application Number: 13/246,629
