Abstract:
A safety valve for swimming pools that senses and then instantly relieves excessively high vacuum levels in the pool&#39;s drain line. Such high vacuum levels occur when an individual becomes trapped by the suction at the pool&#39;s drain port which is connected to the drain line. The valve relieves the high vacuum level in the pool&#39;s drain line and the suction at the drain port by bleeding air into the pool&#39;s drain line, causing the pump connected to the drain line to lose prime. The valve is equipped with means for adjusting the vacuum level at which it actuates to accommodate varying vacuum levels found at different pools.

Description:
This application claims benefit of U.S. Prov. No. 60/274,954 filed Mar. 12, 2001. 
    
    
     BACKGROUND 
     1. Field 
     The present invention relates to pool safety valves that bleed air into the pool&#39;s drain line to relieve excessively high vacuum levels causing the pool&#39;s pump to lose prime and more particularly to such valves that include provisional to adjust on site the trip level at which air is bled into the pool&#39;s drain line. 
     2. Prior Art 
     There have been numerous cases of serious injuries and deaths caused by high vacuum levels at a pool&#39;s drain port which holds an individual to the drain port and in some cases causes disembowelment. When such an incident occurs, the vacuum level in the drain line leading from the drain port to the pool&#39;s pump rises sharply. 
     Various safety valves have been developed in which the high vacuum level occurring during such incidents is sensed and used to trip the valve and allow air to bleed into the drain line, causing the pump to lose prime. Although such valves function to some degree, they generally exhibit two problems. The first is they are often set at the factory to a predetermined trip level which does not always correspond to an appropriate level for a particular pool. Variations in pumps, pipe diameters, pipe length and the number of turns and pitches in a pipe line, all affect the vacuum level at which a safety valve&#39;s trip level should be set. This setting is best done at the pool site. 
     The second problem is related to the valve&#39;s reliability. Virtually all valves include gaskets which must remain sealed if the valve is to function properly. If a gasket becomes dislodged from its seat, it can allow air to leak around the closure elements of the valve, causing the pump to lose prime when there is no emergency. This effectively shuts down the pool and can only be remedied by removing the valve and having it repaired, which often requires the valve to be returned to the factory. 
     A safety valve is needed which can be easily adjusted in the field by a service technician to a trip level that is appropriate for each site. For improved reliability, a safety valve is needed that overcomes the leakage past gaskets that often occurs because the gasket becomes unseated. These needed improvements are provided by the valve of the present invention described in the following sections. 
    
    
     BRIEF DESCRIPTION OF THE FIGURES 
     FIG. 1 is a prospective view of the present invention showing it to include a safety valve housing, a connection to the pool&#39;s drain line, a lock out pin release, an end cap, an air vent, and a vacuum gage. 
     FIG. 2 is an exploded view of the present invention showing the internal elements of the valve. 
     FIG. 3 is an enlarged cross sectional view of the valve&#39;s end-cap showing the valve closure elements including a gasket, an “O”-ring and a cone shaped plunger which is designed to engage the “O”-ring to close the valve. 
     FIG. 4A is a side cross sectional view of the end of the safety valve housing which contains the valve adjustment access port point. 
     FIG. 4B is a side cross sectional view of the end cap valve closure elements and the lock out pin 2mechanism for maintaining the valve open once the valve has been tripped. 
    
    
     SUMMARY 
     An object of the present invention is to provide a pool safety valve which can be adjusted on site to a selected trip level to accommodate the varying vacuum level found at different pools. 
     An object of the present invention is to provide a valve with a cone-shaped plunger element that adjusts for wear to extend the operating life of the valve. 
     An object of the present invention is to provide a pool safety valve which prevents air leakage about the valve closure elements to further extend the opening life of the valve. 
     The present invention is a safety valve for swimming pools that senses and then instantly relieves excessively high vacuum levels in the pool&#39;s drain line. Such high vacuum levels occur when an individual becomes trapped by the suction at the pool&#39;s drain port. The drain port is connected to the pool&#39;s pump by way of the drain line. The valve relieves the high vacuum levels in the pool&#39;s drain and the suction at the drain port by bleeding air into the drain line, causing the pump to lose prime. The valve is equipped with means for adjusting the vacuum level at which it actuates to accommodate varying vacuum levels found at different pools. 
     The valve closure element includes a cone-shaped plunger which engages a sealing O-ring. Wear or ageing of these elements is accommodated by the cone shaped plunger which simply moves further into the O-ring as the opening in the O-ring increases to insure closure of the valve. Another failure which occurs with some valves with age is in a gasket seal which is usually positioned behind the O-ring. If the gasket becomes separated from its seat, air is then allowed to leak about the O-ring, which will cause valve failure. In the present invention, the gasket is clamped in place, preventing it from loosening its position and preventing air from leaking past the O-ring. The valve life is significantly improved by these features. 
     The pressure applied to keep the valve elements closed determines the vacuum level at which the valve will open or be tripped. In the present invention, a screw adjustment which increases the spring pressure placed against the valve closure elements is accessible from outside of the valve to allow the valve to be easily set at each pool site by the installer to a different trip level as necessary to accommodate the different vacuum levels found at each pool site. 
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 is a prospective view of the present invention  1 , showing it to include a safety valve housing  2 , a coupling section  3  located beneath the housing, a lock out pin release  4  on the lower section of the housing, an end cap  20  located at the left end of the housing, an air vent  6  and a screen  6 A located to the left in the end cap and a vacuum gage  5  located on top of the housing. In the use of this valve, a stub line connected to the drain line by means of a “T” rises upward from the drain line and is connected to the coupling section  3 . This stub couples the vacuum in the drain line to the valve. This vacuum level can be read at the vacuum gage  5  and this reading is used to set the trip level of the valve. 
     A security cap  8  on the right side of the housing is removed with a special tool  8 A and a screw driver is inserted, engaged and then rotated to set the trip level. When the valve is tripped, it allows air through vent  6  to pass through the valve and the coupling  3  to the drain line, causing the pump which is connected to the drain line to lose prime and free anyone trapped at the pool&#39;s drain port. Once the valve has been tripped, it is locked in the open or venting position by a lock out pin until it is manually released by pressing the lock out pin release  4 . 
     FIG. 2 shows the valve in an exploded view of the internal components of the valve which include from right to left in this Figure, a security cap  8 , a second “O”-ring  9 , an adjustment screw  10 , a sleeve for the main piston  11 , a spring guide retainer  12 , a screw  12 A which holds the retainer to the sleeve, a main spring  13 , a main piston  14 , a bearing ring  15 , a cone-shaped plunger  16 , a sealing bushing  17 , a gasket  18 , a first “O”-ring  19 , a third “O”-ring  19 A, the end cap  20 , a compression bushing  21  and interconnected threads  22  of the sealing bushing  17  and compression bushing  21 . These components are placed together within the safety valve in the same order as they are listed above. The security cap  8  is used to close the right end of the housing and discourage unauthorized adjustment of the valve&#39;s trip level. 
     FIG. 3 is an enlarged cross sectional view of the valve&#39;s end cap  20  showing the valve&#39;s closure elements including the gasket  18 , the first “O”-ring  19 , and the cone shaped plunger  16 . The plunger is designed to engage the “O”-ring  19  and close the valve. The cone shaped plunger  16  is in reality a truncated cone. The flattened area at the truncation is designed to permit the plunger to contact the “O”-ring without receiving interference from the sealing bushing  17 , located just to the left of the “O”-ring in this Figure. 
     In the operation of the closure elements, the tapered edges  16 A of the plunger are pushed into engagement with the “O”-ring to make contact with the “O”-ring and seal off the air from a passageway  23  which passes through the center of the end cap. When the valve is opened, air flows through the screen  6 A at the vent  6  on the left of the end cap, through the passageway  23 , and the coupling  3  and then on to the pool&#39;s drain line. The screen  6 A, located over the vent is designed to keep debris and insects from entering and clogging the valve. As the “O”-ring wears with age, the tapered edges of the cone shaped plunger simply move further into the “O”-ring to maintain contact with the “O”-ring, thereby extending the life of the valve. 
     A second factor extending the life of the valve is in the design of the gasket  18 , the sealing bushing  17 , and the compression bushing  21 , all of which are located in the end cap  20 , as shown in FIG.  3 . The gasket  18  is formed of two parts, a vertical or flat gasket portion and a horizontal web portion which is attached at its right end to the first “O”-ring  19 . 
     In some prior art valves, the gasket only has a horizontal web portion which is located in a round slot in the end cap. If the web is dislodged or simply separated from the wall of the slot, air from the passageway  23  will find its way about the web and leak past the closure elements, the “O”-ring and plunger, to defeat the valve. In this case, the valve appears to be open when it is intended to be closed. The pump loses prime and the pool cannot be operated. 
     To overcome this problem in the present invention, the flat gasket portion is clamped between the sealing bushing  17  and compression bushing  21 . This prevents any air from leaking around the bushing. These two bushings are threaded together to clamp the flat gasket between them. The intermeshed threads of these bushings is at location  22 , as can be seen in FIG.  3 . 
     The way in which the closure elements are drawn together to close the valve and the force used to open the valve is best explained with reference to FIG.  2 . The closure elements are urged into contact by the force of the spring  13  that presses against the main piston which in turn presses against the plunger  16 . The plunger  16  is attached to the main piston and is pressed against the “O”-ring to close the valve. 
     The “O”-ring  19  in this Figure is actually attached to the flat gasket as shown in FIG.  3 . When an excessive vacuum occurs in the drain line, it is transmitted through the coupling  3  into the housing and through holes in the main piston  14 , drawing the plunger back which, in this case, is to the right in FIG.  3 . That action draws the plunger back and away from the “O”-ring. The result of this action is the opening of the closure elements which allows air in the passageway  23  to flow past the closure element to the coupling section and the drain line. 
     The pressure applied by the spring can be varied to adjust for the normal operating vacuum level found at different pool sites. This is done by first removing the security cap, which is simply threaded out of the housing. A screw driver is applied to the adjustment screw  10  which has t threads on it periphery that engage the housing. As the adjustment screw  10  is advanced into the housing, it passes through a central hole in the sleeve  11  and presses against the spring, increasing the spring&#39;s pressure against the main piston and the cone plunger  16 . Threading the adjustment screw in the opposite direction has the opposite effect, resulting in reducing the pressure on the plunger. 
     At a particular site, the actual required spring adjustment can be determined by installing the safety valve and adjusting the spring tension until no air leakage occurs through the vent  6 . Once properly set, vacuum levels above “normal” operating will cause the plunger to pull back and the valve is opened. 
     Once the valve is opened, it must be locked in the open position to allow individuals trapped at the drain port to leave the vicinity of the drain port. This is done by means of a lock out pin  7  which rides on a bearing ring  15  The bearing ring is mounted on the main piston  14 . As the piston  14  is pulled back by the excess vacuum, the pin first rides on the ring  15  and then falls in front of the main piston  14 , preventing it and the plunger, to which it is attached, from returning to a closure position against the first “O”-ring  19 . The only way that the piston can be released is by manually releasing it. This is done by pushing the lock pin release  4  on the lower side of the pump housing. This is only done after any individual that has been trapped at the drain port is well clear of the port. 
     It should be noted that the bearing ring  15  serves an important function other than as a bearing surface for the lock out pin  7 . It is also used to seal the piston about its periphery, preventing air from the passageway  23  from bypassing the main piston. Once the valve closure elements have opened, the air presses against the main cylinder forcing it back to the position where it is locked by the lock pin. 
     A portion of the air pressing on the face of the piston is allowed to pass through holes  14 A and  14 B and on through the coupling section  3  to cause the pool pump to lose prime. These holes are large enough to allow sufficient air to pass to cause the loss of prime, but are small enough to allow the pressure of the air to move the cylinder. There is a critical range in hole size that is maintained to accomplish both functions. 
     The remaining components shown in FIG. 2 have simple mechanical function and require no further explanation as their functions are obvious from their respective name which are listed in connection with the description of FIG. 2 above.