Embodiments of the present invention generally relate to a stock tank, and, more particularly, to a system and method of insulating a stock tank.
Stock tanks are commonly used in livestock operations to provide drinking water to animals. Generally, stock tanks are located outdoors within a pen where animals are kept. As such, the stock tanks may be exposed to temperature extremes as well as wind, rain, and snow.
Typically, care is taken to ensure that water within a stock tank does not freeze during winter months, as livestock are unable to drink frozen water. To this end, an electric stock tank de-icer may be used to supply heat to the water within the stock tank.
Many modern stock tank de-icers are thermostatically-controlled to activate when the water temperature approaches freezing and deactivate when the water is heated to a predetermined temperature. The de-icers are typically rated at 1000 watts or more in order to provide enough heat to the tank.
In order for a de-icer to heat the water and then deactivate, heat loss from the stock tank must be less than the heat input from the de-icer. If the heat loss is greater than the heat input, the water will continue to lose heat and will eventually freeze even if the de-icer is running all the time. Because a 1000 watt heater can be expensive to operate continuously, it is desirable to reduce its duty cycle by reducing the heat loss from the water by insulating the tank.
Farmers and ranchers often position a stock tank against a wall of an outbuilding or partially surround the tank with straw bales in order to block the wind. While this is effective in reducing the accelerated heat loss due to wind chill, it does not ameliorate the normal heat loss via convection and radiation.
U.S. Pat. No. 4,100,885 (“Kapplinger”) discloses a specialized stock tank having insulated structural components that are configured to prevent heat loss during the winter. Kapplinger includes a well that extends down into the water as an integral part of the unit. The well is configured to minimize the amount of water that is exposed to the cold air. However, while the specialized stock tank of Kapplinger significantly reduces heat loss, as a specialized tank, it is inapplicable to numerous existing conventional stock tanks.
U.S. Pat. No. 5,921,230 (“Vessells”) discloses an insulating blanket for a hot water heater where the blanket contains piping for circulating of hot waste gases. The blanket disclosed in Vessels forms a part of the heating system itself, and is not a passive insulating device.
U.S. Pat. No. 4,808,356 (“West”) discloses a jacket around a water heater where expanding foam may be used to fill the intervening space. However, the expanding foam jacket is susceptible to saturation and degradation when exposed to water, thereby adversely affecting the insulating properties.
Other enclosures have been proposed for jacketing hot water heaters. The jacketed hot water heaters are configured to contain water in the event of a leak in the water tank. These jacketed water heaters do not, however, provide thermal insulation in an outdoor environment while providing access to the water.
With respect to swimming pools, for example, in order to reduce heat loss from the water surface, floating insulation is often used. Foam or bubble wrap is often floated on the surface of the water to provide a layer of trapped air thereby significantly reducing heat loss. However, while the water level in a swimming pool stays constant, the water level in a stock tank is continually changing.
The walls 14 of the stock tank 10 taper downward from the lip 16 to the base 12. The walls 14′ of the stock tank 10′ step down from the lip 16′ to the base 12′.
A water-retaining cavity 18 is defined between the walls 14 and the base 12. Similarly, a water-retaining cavity 18′ is defined between the walls 14′ and the base 12′. The water-retaining cavities 18 and 18′ are configured to retain water for animals to drink.
Because the retaining walls 14 and 14′ slope and step inwardly from the lips 16 and 16′, respectively, to the base 12 and 12′, respectively, as animals drink water within the cavities 18 and 18′, the water level drops in the tank and the exposed surface area of the water surface decreases. Accordingly, if a slab of rigid foam on the surface of the water were to be used to insulate the stock tanks 10 and 10′, as an animal drank and the water level decreased, the slab would wedge in the tank and an air gap would open between the foam slab and the water, thereby adversely affecting the effectiveness of the insulation. Conversely, if the foam slab was sized to fit the bottom of the tank, there would be exposed gaps around its edge when the tank is full, thereby exposing around 20% of the water surface to the cold air.
Overall, exposure to rain and snow limits the materials that are used to insulate a stock tank. Additionally, care should be taken to ensure that animals are discouraged from chewing the insulating materials. Additionally, the insulating material should prevent free movement of air between the insulating material and the walls of the stock tank in order to preclude heat loss by convection. The systems and methods explained above, however, do not adequately address all of these considerations.
Certain embodiments of the present invention provide a system for insulating a conventional stock tank configured to retain drinking water for an animal. The system includes at least one insulating member configured to secure to the conventional stock tank. The at least one insulating member is configured to trap air between the at least one insulating member and one or both of a retaining wall of the conventional stock tank or a surface within a water-retaining cavity of the conventional stock tank.
The at least one insulating member may include an insulating jacket configured to wrap around the conventional stock tank.
The insulating jacket may include a flexible lining, and a foam blanket attached to, or enclosed within, the flexible lining. The foam blanket may be formed of a water-resistant, closed-cell material. Alternatively, the foam blanket may be formed of open-cell foam. The flexible lining may be formed of an elastomeric material. At least one draw string may be secured to the flexible lining.
The insulating jacket may include a plurality of vertical air pockets. The insulating jacket may include a plurality of spacer tubes, wherein the spacer tubes are configured to be sandwiched between the insulating jacket and the retaining wall of the conventional stock tank.
The at least one insulating member may include a cover suspended above an opening of the conventional stock tank by a rigid frame. The cover may include at least one flap over at least one opening. The flap is configured to be engaged by an animal. For example, the animal may nudge the flap open and position its head through the opening to gain access to the water within the stock tank. The at least one flap may be spring-biased, connected to the cover through at least one hinge, or the like.
The at least one insulating member may include a plurality of flexible vertical straps connected to a covering wall. The plurality of flexible vertical straps are configured to be positioned about an opening of the conventional stock tank.
The insulating member may include a drinking chute configured to be secured to the conventional stock tank, and a flexible cover that stretches from an upper portion of the conventional stock tank to upper portions of the drinking chute. A float may be positioned within the drinking chute.
The at least one insulating member may include a floating cover including a plurality of floating, interlocking insulating blocks.
Certain embodiments of the present invention provide a system for insulating a conventional stock tank configured to retain drinking water for an animal. The system includes an insulating jacket configured to securely wrap around a retaining wall of the conventional stock tank. The insulating jacket is configured to trap air between the insulating jacket and the retaining wall. The system also includes a flexible cover suspended above the conventional stock tank by a rigid frame. The flexible cover is configured to trap air between the flexible cover and a surface (such as a water surface or base of the conventional stock tank) within a water-retaining cavity of the conventional stock tank.
The insulating jacket and the flexible cover may be integrally formed as a single unit.
The system may also include a floating cover including a plurality of floating, interlocking insulating blocks. The floating cover is configured to float on water within the water-retaining cavity of the conventional stock tank.
The foregoing summary, as well as the following detailed description of certain embodiments of the present invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there are shown in the drawings, certain embodiments. It should be understood, however, that the present invention is not limited to the arrangements and instrumentalities shown in the attached drawings.
As noted above,
Heat transfer through the walls of a stock tank, such as the stock tanks 10 and 10′, is given by:
Q=−kA(ΔT/Δx)
where Q is the rate in watts at which heat is transferred, k is the coefficient of thermal conductivity for the wall material, A is the wall area through which the heat passes, ΔT is the difference in temperature on opposite sides of the tank wall, and Δx is the thickness of the tank wall.
For a given area A, the heat flow Q for a certain temperature difference ΔT can be reduced by either choosing a material with a small thermal coefficient k or by increasing the thickness Δx of the material. For water, the coefficient k is 0.6 watts/meter-degree Kelvin (w/m·K), but for glass-filled polymer, of which most plastic stock tanks are formed, the coefficient is also around 0.6 w/m·K. For a stock tank made of galvanized steel, the value for k can be as high as 50. Thus, the walls of the stock tank provide little to no insulation for the water in either case.
On the other hand, air has a thermal coefficient of 0.025 w/m·K and provides good insulation. A layer of trapped air (around ten times thicker than the walls of the stock tank) between the stock tank and the outside environment would decrease the heat flow through the tank walls by a factor of around 240. Accordingly, a stock tank losing heat through its walls at a rate of 400 watts would instead lose heat at a rate of less than 2 watts. Thus, for a tank having walls that are 0.25 inches thick, surrounding the tank with air insulation 2.5 inches thick could reduce the heating required to keep the water ice-free by around 280 kilowatt-hours per month. Therefore, an enclosure that traps air around the stock tank would form an effective way of insulating the tank.
The jacket 20 includes a foam blanket (hidden from view) that is attached to, or enclosed within, a flexible, durable lining 22. The foam blanket is a water-resistant, closed cell construction. Optionally, the foam blanket may be formed of open-cell foam, as long as the lining 22 is water-tight and completely encloses the foam blanket. Accordingly, the lining 22 may be formed of an elastomeric material, such as rubber, or the like.
As shown in
The jacket 20 is configured to wrap completely around a large stock tank, such as a 150 gallon tank, while also being able to wrap around smaller tanks. When wrapped around a smaller tank, portions of the jacket 20 may overlap other portions of the jacket 20.
As shown in
A clip 36 may be used to securely fasten the upper edge 28 of the jacket 20 to the lip 16 of the stock tank 10. For example, a first end 38 of the clip 36 may latch around the draw string 24, while the opposite end 40 of the clip 36 wraps around an inner surface of the lip 16, thereby securely clipping the upper edge 28 of the jacket 20 to the lip 16. The clip 36 may be formed of metal or plastic, for example. A plurality of clips 36 may be used to secure the jacket 20 to the stock tank 10, thereby ensuring that the upper edge 28 of the jacket 20 does not slide down the retaining walls 14.
The jacket 20 and the air gap 34 between the jacket 20 and the retaining wall 14 provide water and air-tight insulation for the stock tank 10.
As shown in
As shown in
Once the jacket 42 is inflated, the air trapped within the air pockets 44 provides an insulating layer around the stock tank 10 or 10′ The vertical orientation of the air pockets 44 allows the jacket 42 to be easily wrapped around the stock tank 10 or 10′ without creasing the jacket 42. Optionally, the air pockets 44 may be horizontally oriented.
Also, the draw strings shown and described with respect to
The relationship between air pressure and volume within the inflated jacket 42 at various temperatures is given by:
p
1
V
1
/T
1
=p
2
V
2
/T
2
where p is pressure, V is volume, and T is temperature. For a given pressure of 1 atmosphere for p1 and p2, a decrease in temperature will cause a decrease in the volume that the air occupies. If the jacket is filled to a pressure of 1 atm when the air temperature is 300 K (80° F.), the volume V2 occupied by the air when the temperature drops to 233 K (−40° F.) will be 0.78V1, or 22% less, and the jacket 42 will sag. To compensate, the jacket 42 may be filled to a pressure of at least 1.29 atm so that, when the temperature drops, the air inside the jacket 42 will be greater than 1 atmosphere and the jacket 42 will not sag. To that end, the jacket 42 may be inflated when the temperature is low. As the outside temperature increases towards the approach of spring, the pressure inside the pockets 44 of the jacket 42 will increase but the construction allows it to easily withstand 1.5 atmospheres.
The tubes 54 space the air-tight wall 58, or cover, from the stock tank 10 or 10′. The tubes 54 and the cover 58 form an air pocket between the cover 58 and the retaining walls of the stock tank 10 or 10′. The tubes 54 may be formed of foam or the like, or can be plastic inflatable tubes.
The tubes 54 may be secured in position with tape or straps that extend downwardly from the walls of the stock tank 10 or 10′. Alternatively, short sections of the tubes 54 may be attached to the walls of the stock tank 10 or 10′ and spaced around the periphery of the stock tank 10 or 10′ to form spacers for the cover 58. Such a configuration may be used when the walls of the stock tank 10′ are stepped, such as in
The draw strings shown and described with respect to
The lip of the stock tank 10 or 10′, therefore, acts as a spacer that holds the jacket 60 out and away from the retaining walls. The drawstring 64 is engaged to decrease the size of the opening of the jacket 60 so that its diameter is less than that of the diameter of the opening defined within the lip of the stock tank 10 or 10′.
The jacket 60 may also include a lower drawstring, such as shown in
The cover 82 may include a draw string (not shown) in order to securely cinch the cover 82 around the lip 16 or 16′.
The cover 82 includes flaps 84 that cover openings (hidden by the flaps 84). The flaps 84 are pivotally connected to the cover 82 at upper edges 86. The flaps 84 may pivotally open about the upper edges 86, which define connection joints with the cover 82.
While the cover 82 is shown having two flaps 84 on one side, the cover 82 may include more or less flaps 84 than those shown. For example, the cover may include one large flap that spans from the area shown by one flap 84 to another flap 84, in order to accommodate animals of varying sizes. For example, a steer with large horns may need a large opening in order to pass its head through an opening. Accordingly, the covered stock tank 80 may include one large opening and flap 84 on each side that spans over most, if not all, of the length of the cover 82.
An animal may poke its head through the openings covered by the flaps 84 in order to drink water within the stock tank 10 or 10′.
The flap 84 may be hinged so that it closes through gravity. Optionally, the flap 84 may include a connection joint that is spring-loaded, counterbalanced, or the like.
Also, alternatively, the flap 84 may be connected to an underside of the cover through a spring-biased mechanism. In this manner, the animal would push the flap open into the enclosed area of the covered stock tank 80. When the animal 90 removes its head, the spring-biased mechanism forces the flap 84 back into a closed position.
The covered stock tank 100 allows animals of varying shapes and sizes to gain access to water within the stock tank 10 or 10′. Because animals may poke their heads through the straps 108 at various points around the stock tank 10 or 10′, there is no need for strategically placed openings covered by flaps.
A jacket 122 is secured around the stock tank 10′, as discussed above. Spacers 124 may be used to space the jacket 122 from the retaining wall 14′ of the stock tank 10′. The jacket 122 may be integrally connected to a cover 126 that extends and stretches over the lip 16 and onto an upper edge of a drinking chute 128. The cover 126 traps air between the inner surface of the retaining wall 14′ and the drinking chute 128.
A float 130 is positioned within the drinking chute 128. The float 130 may be formed of plastic, foam, wood, or the like. As the water level drops, the float 130 recedes within the drinking chute 128. As such, the float 130 covers the water within the drinking chute 128. However, an animal may push the float downward to gain access to the water.
Referring to
The blocks 152 include shell extensions 154 that extend underneath top surfaces 156 of the blocks 152. The shell extensions 154 prevent adjacent blocks 152 from sliding underneath one another when an animal pushes the block(s) 152 underwater to get a drink.
Thus, an animal may push the block(s) 152 under water in order to gain access to the water. When the animal removes its head from the blocks 152, the buoyancy of the blocks 152 causes them to float on the surface of the water, thereby covering and insulating the water within the stock tank 10′.
Thus, embodiments of the present invention provide systems and methods of insulating conventional stock tanks. Embodiments of the present invention may be used with any stock tank. That is, the embodiments of the present invention do not require a specialized stock tank.
Instead of a specialized stock tank, embodiments of the present invention provide systems and methods of retrofitting conventional stock tanks so that they are insulated.
Embodiments of the present invention provide systems of insulating a stock tank that are formed of materials that are not degraded by the elements, such as rain or snow. Additionally, embodiments of the present invention provide insulating systems that do not include components that may be chewed by animals. Further, embodiments of the present invention provide insulating systems that prevent free movement of air between the insulating material and the walls of the stock tank in order to preclude heat loss by convection.
While various spatial terms, such as upper, bottom, lower, mid, lateral, horizontal, vertical, and the like may used to describe embodiments of the present invention, it is understood that such terms are merely used with respect to the orientations shown in the drawings. The orientations may be inverted, rotated, or otherwise changed, such that an upper portion is a lower portion, and vice versa, horizontal becomes vertical, and the like.
While the invention has been described with reference to certain embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from its scope. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.
The present application claims priority to U.S. Provisional Application No. 61/258,942, entitled “Stock Tank Insulator,” filed Nov. 6, 2009, which is hereby incorporated by reference in its entirety.
Number | Date | Country | |
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61258942 | Nov 2009 | US |