Abstract:
A float control valve for liquid treatment apparatus is located sufficiently far above the level of the liquid being treated that forces created by the liquid, or forces created during movement of the apparatus, do not harm the control valve or interfere with its functioning.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to liquid treatment apparatus, and more particularly to the control of the captive pressurized air volume in liquid treatment tanks. Control valves using the position of a float in a liquid being treated do not always operate reliably when the liquid is being treated at a relatively high pressure (e.g. above 50 psi). Prior art valves of this type frequently sputter air and the liquid being treated when they vent the treatment tanks to the atmosphere. Also, when the float itself is located at or closely adjacent the level of a liquid being treated, currents and movement of the liquid may interfere with the movement of the float and cause the control mechanism to malfunction; short cycling of a pressure pump activated by the control mechanism may also occur. 
     OBJECTIVES OF THE INVENTION 
     Accordingly, it is an object of this invention to provide improved liquid treatment apparatus and controls therefor. 
     Another object is to provide float controls for liquid treatment apparatus in which the float itself is located a sufficient distance above the surface of the liquid to prevent currents and movement of the liquid from interfering with the operation of the float. 
     An additional object is to provide controls for a pump that pressurizes a tank that prevent short cycling of the pump. 
     A further object is to provide pressurized liquid containing tanks with controls that facilitate detection and repair of leaks and malfunctioning components. 
     Another object is to provide a float control valve arrangement that flushes out a pipe that brings liquid to the float. 
     A further object is to provide a float control valve for large tanks that can be easily changed to operate at different liquid levels in such tanks. 
     An additional object is to prevent damage to liquid level controls during shipment of the apparatus in which the controls are used. 
     Another object is to provide for the easy replacement of float control valves in the field. 
     A further object is to provide the pressure control line, pressure gage and float valve assembly of a liquid treatment tank with pressure through a drop pipe in a way that isolates the pressurized air space in the tank from these components so as to prevent a leak or failure of any of these components from causing the system to shut down as a result of loss of air pressure in the tank. 
     A further object is to provide liquid level float control valves that are durable, economical, easy to use and to maintain and to repair, and which do not possess defects found in similar prior art float valves. 
     Other objects and advantages of the liquid treatment controls incorporating this invention will be found in the specification and claims and the scope of the invention will be set forth in the claims. 
    
    
     DESCRIPTION OF THE DRAWING 
     FIG. 1 is a partially cross sectional schematic view of prior art liquid treatment apparatus. 
     FIG. 2 is a partially cross sectional schematic view of liquid treatment apparatus in accord with this invention. 
     FIG. 3 is an enlarged cross sectional view showing the float control from the embodiment of FIG. 2 in closed position. 
     FIG. 4 is an enlarged cross sectional view showing the float control from the embodiment of FIG. 2 in open position. 
     FIG. 5 a top plan view of the main body portion from the embodiment of FIGS. 2 and 3. 
     FIG. 6 is a side view of the main body portion 
     FIG. 7 is a cross sectional view taken along the line  7 — 7  in FIG.  6 . 
     FIG. 8 is a bottom view of the stopper from the embodiments of FIGS. 2 and 3. 
     FIG. 9 is a side view of the stopper. 
     FIG. 10 is a cross sectional view taken along the line  10 — 10  in FIG.  9 . 
     FIG. 11 is front view of the float from the embodiment of FIGS. 2 and 3. 
     FIG. 12 is a side vie of the float. 
     FIG. 13 is a top plan view of the float. 
     FIG. 14 is a bottom view of the float. 
     FIG. 15 is a top plan view of the gate from the embodiment of FIGS. 2 and 3. 
     FIG. 16 is a bottom view of the gate. 
     FIG. 17 is a front view of the gate. 
     FIG. 18 is a side view of the gate. 
     FIG. 19 is a rear view of the gate. 
     FIG. 20 is a partially cross sectional expanded view showing the float, gate and stopper in assembled relationship. 
    
    
     DESCRIPTION OF THE INVENTION 
     The drawing in FIG. 1 is a simplified depiction of the apparatus for removing hydrogen sulfide from potable water shown in FIG. 1 of my U.S. Pat. Nos. 6,074,562 and 6,080,306. The level of the liquid in a tank  1  fluctuates between an upper level  2  and a lower level  3 , leaving an air space in the upper part of the tank. The pressure in tank  1  is maintained at level for treatment (e.g. 60-75 psi) by a liquid pump  4  that is connected to a source  5  of the liquid being treated. The pump  4  is turned on and off by a conventional electrical pressure switch  6  that is connected by an air line  7  to the top of tank  1  through an air line connector  8 . An atmospheric air vent  9  is connected to a drop pipe  10  that extends downwardly into a float actuated ballast vent valve  11 . The float actuated valve  11  is located at or closely adjacent the liquid level that it controls. The drop pipe  10  is vertically offset from the influent riser pipe  12  to prevent eddies and currents in the tank incoming water supply from interfering with the operation of the float actuated valve  11 . Accumulated compressed air in the top of tank  1  lowers the water to the level  3 , at which level the float opens valve  11  and releases air to the atmosphere through drop pipe  10  and air vent  9 . This lowers the pressure in air line  7  and closes switch  6  and turns on pump  4 . The liquid that is pumped in raises the liquid level to the level  2 , where the float closes the valve  11 . This shuts off the air vent  9 , which raises the pressure in the air line  7  and opens switch  6  shutting off the pump  4 . A pressure gage  14  may be connected to the tank  1 , which may be supported on a stand  15 . Hydrogen sulfide may be removed from potable water, and a valve  16  may be used to control the flow of treated water through an effluent pipe  17  and a valve  18  used to control the flushing of precipitated sulfur and waste from tank  1  through a waste pipe  19 , as disclosed in my above patents. 
     The invention shown in FIGS. 2-20 improves the apparatus disclosed in my above patents by locating the float in the pressurized air volume control valve a distance remote from the level of the liquid being treated. FIG. 2 shows liquid treatment apparatus that is essentially the same as the prior art disclosed in FIG. 1, except for the structure and operation of the float control valve  20 . Incoming liquid to be treated enters a tank  21  through an inlet riser pipe  22 . The liquid may be treated as disclosed in my above mention patents, and treated liquid may leave tank  21  through an effluent outlet pipe  23  controlled by a valve  24 . Precipitated and waste particles may be flushed from the bottom of tank  21  through a waste outlet pipe  25  controlled by a valve  26 . 
     During the liquid treatment process that takes place in tank  21  an air space  28  is maintained in the upper part of the tank, and the level of the liquid will fluctuate between an upper level  29  and a lower level  30 . The pressure in the tank  21  is maintained at the elevated treatment level (e. g. 60-75 psi) by a liquid pump  31  that is connected to the source  32  of untreated liquid, such as potable water containing hydrogen sulfide. The pump  31  is actuated by a conventional electrical pressure switch  33  that is connected by an air line  34  to a removable stopper  35  in control valve  20 , which has an atmospheric air vent  36 . A straight, hollow, cylindrical drop pipe  37  has its upper terminal end  38  connected to the control valve  20 . The pipe  37  extends vertically downwardly so that its lower terminal end  39  is at the level of the liquid in tank  21  directly in line with the inlet riser  22  at the center of the tank. The pipe  37  is completely unobstructed throughout its length, which is many times its diameter (e.g. length 24 inches—diameter 1 inch). 
     Accumulated compressed air in the top of tank  21  lowers the liquid to the level  30 , at which level the control valve  20  opens the air vent  36  and releases air to the atmosphere through drop pipe  37  and the air vent. This lowers the pressure in air line  34  and closes switch  33  which turns on the pump  31 . The liquid that is pumped in raises the liquid level to the level  29  which causes water to displace the escaping air in the pipe  37  until liquid reaches a float in the valve  20  and causes the float to rise so as to close the air vent  36 . Closing the air vent raises the pressure in the air line  34 , which opens switch  33  shutting off the pump  31 . Tank  21  may be supported on a stand  40  and may have a pressure gage  41 . Hydrogen sulfide may be removed from potable water in tank  1 , as disclosed in my above patents. 
     Valve  20  has a main body portion  45  with external threads  46  that mate with threads  47  in the upper center hole  49  of tank  21 , which is centered on the central axis  48  of the tank. A peripheral flange  50  extends from the main body portion, and a gasket  51  is compressed between the flange and the top edge  52  of the tank when the main body portion is screwed into the hole  47 . Stopper  35  has external threads  53  that mate with internal threads  54  in a center hole  56  in the main body portion so as to provide a pressure tight fit. Stopper  35  has a hollow interior chamber  55 , and air line  34  is pneumatically connected to chamber  55  through a port  57 . A grommet  58  and gasket  59  may be used to secure the air line in place. Air vent  36  is connected to chamber  55  through a small hole  60  in the tapered conical end  61  of a nipple  62  that extends downwardly from a stub pipe  63  at the end of the vent. A length of flexible tubing  64  may be a held in vent  36  by a grommet  65  and gasket  66 . The tubing  64  is flexible in order to deter intrusion into the valve by insects such as wasps. A threaded hole  67  may be provided in stopper  37  for an air pressure gage  41 . 
     Vent  36  is opened and closed by a movable closure member or gate  70 , which has a pair of aligned cylindrical axles  71  and  72  protruding from the ends of opposed arms  73  and  74 . Stopper  37  has a pair of aligned bearings  75  and  76  projecting from its lower end. Gate  70  is made from flexible resilient material, so the arms  73  and  74  can be squeezed toward each other, and this enables insertion of the axles  71  and  72  into circular holes in the bearings  75  and  76  so as to pivotally attach an end of the gate to the stopper. Gate  70  has a T-shaped opening  77  with a main slot  78  and cross slot  79  in its center portion  80 . A vent closing plastic seal  81  is held in a hole  82  adjacent the end of the center portion. 
     A hollow cylindrical float  85  moves upwardly and downwardly with the level of liquid in a hydropneumatic float chamber  86  in main body portion  45 . The float has several ridges  87  along its sides and bottom to center the float and provide space for liquid to flow around the float in chamber  86 . A T-shaped rod  88  extends upwardly from the top of float  85 . The stem  89  of the rod  88  is sized to slide in the main slot  78  in gate  70 . The cross arm  90  of the rod can be inserted through the cross slot  79 , and the movement of the cross arm  90  in the slot  78  will pivotably connect the opposite end of the gate  70  to the float  85 . The upper terminal end  38  of pipe  37  is secured in a hole  91  in the bottom of main body portion  45  below float  85 . The float chamber  86 , internal threads  54  and external threads  46  on the main body portion and the pipe  37  are all coaxial with the central axis  48  of the tank  21 , and the vent closing seal  81  is offset from the axis  48 . Ridges  92  on the outside of the main body portion strengthen its bottom end in the area where the pipe  37  is attached. 
     In FIG. 3 the valve  20  is shown in the position that closes the air vent  36 . The liquid level  29 ′ is above the level  30 , so liquid has filled drop pipe  37  and risen into the float chamber  86 . The liquid level  93  in chamber  86  has raised float  85  upwardly and caused gate  70  to pivot upwardly in bearings  75  and  76  until seal  81  bears against the end  61  of nipple  62  and closes hole  60 . This seals the vent  36  from the chamber  86 , which keeps the pressure in chamber  86  and air line  34  above the set point that opens switch  33  and turns off pump  31 . 
     In FIG. 4 the valve  20  is shown in the position that opens the air vent  36 . The liquid level is at the level  30  below the lower terminal end  39  of the pipe  37 . The liquid that was in chamber  86  and pipe  37  has drained out into tank  21 . The falling liquid has moved float  85  downwardly to the bottom of chamber  86 . Lowering of the float has caused the cross arm  90  to pivot the gate  70  downwardly and unseat seal  81  from contact with nipple  62 . This has opened hole  60  and pneumatically connected the chambers  55  and  86  to the atmosphere through vent  36 . This will lower the pressure in the chambers and air line  34  to the set point that will turn on the pump  3 . The pump will run until the liquid rises to the level  29  where liquid in the chamber  86  will raise float  85  and pivot gate  70  to close the vent. Closing vent  36  will raise the pressure in air line  34  until switch  33  shuts off the pump  3 . 
     It has thus been shown that by the practice of this invention, locating the float  85  a significant distance above the uppermost level reached by the liquid in tank  21  prevents the currents and motion of the liquid from interfering with the operation of the control valve  20 . When the vent  36  is opened by control valve  20 , all of the water drains out of the down pipe  37 , and the water must rise for the full length of the pipe  37  before the water can raise float  85  in chamber  86  so as to close the vent and shut off the pump  3 . The time lag built in to the control circuit because of the necessity of the emptying and the filling of pipe  37  before the pump  3  will stop and start prevents short cycling of the pump. The emptying of the pipe  37  also flushes out the pipe and prevents precipitates resulting from the treatment process in tank  21  from clogging the pipe  37  or causing the float  85  to malfunction. If experience shows that the liquid levels in any specific treatment tank should be changed after the tank has been installed, this can be accomplished easily by unscrewing the control valve  20  and screwing in another control valve with a different length of pipe  37  that will maintain the new liquid levels. Also, the fact that the float and other components of the control valve  20  are at the top of the tank, and not at the lower end of a long down pipe  37 , eliminates torque and stress that could damage the pipe or its joint if sudden or violent movements occur when the apparatus is shipped to the site where it is installed. Isolating the pressure control components at the upper end of the drop pipe  37  also makes detection and repair of leaks easier, and prevents system failure resulting from loss of the air space  28 . The float control  20  and its components and attached pipes may be made from any metal or injection moldable plastic usable for potable water service, such as stainless steel or PVC or ABS. 
     While the present invention has been described with reference to particular embodiments, it is not intended to illustrate or describe all of the equivalent forms or ramifications thereof. Also, the words used are words of description rather than limitation, and various changes may be made without departing from the spirit or scope of the invention disclosed herein. It is intended that the appended claims cover all such changes as fall within the true spirit and scope of the invention.