CA1197277A - Propane tank warmer - Google Patents
Propane tank warmerInfo
- Publication number
- CA1197277A CA1197277A CA000421443A CA421443A CA1197277A CA 1197277 A CA1197277 A CA 1197277A CA 000421443 A CA000421443 A CA 000421443A CA 421443 A CA421443 A CA 421443A CA 1197277 A CA1197277 A CA 1197277A
- Authority
- CA
- Canada
- Prior art keywords
- heating device
- vessel wall
- self
- backing
- vessel
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B3/00—Ohmic-resistance heating
- H05B3/40—Heating elements having the shape of rods or tubes
- H05B3/54—Heating elements having the shape of rods or tubes flexible
- H05B3/58—Heating hoses; Heating collars
Abstract
ABSTRACT OF THE DISCLOSURE
A portable electrical heating device for spot-warming of a vessel containing pressurized liquid and vapor phases is described. The heating-device comprises an electrically and thermally insulating weather-resistant backing, a self-limiting electrically resistive element secured to the backing, and attachment strips for securing the heating device to the wall of a vessel bringing the self-limiting element into heat-transfer relation to the wall so as to spot-warm a portion of the vessel walls and vaporize liquid phase in proximity to this portion.
A portable electrical heating device for spot-warming of a vessel containing pressurized liquid and vapor phases is described. The heating-device comprises an electrically and thermally insulating weather-resistant backing, a self-limiting electrically resistive element secured to the backing, and attachment strips for securing the heating device to the wall of a vessel bringing the self-limiting element into heat-transfer relation to the wall so as to spot-warm a portion of the vessel walls and vaporize liquid phase in proximity to this portion.
Description
~g7277 This invention relates to an electrical heating device and, more particularly, to a portable 'iheat-patch" adapted to warm a portion of the surface of a vessel to promote vaporiza-tion of fluid contained therein.
Northern exploration and deve:Lopment is expanding rapidly across the continent. In most cases, these activities are centered around isolated camps. In many of these camps, pro-pane and similar gases are used as fuel. Due to the remoteness of the locations and the need for camp portability such fuels are generally transported and stored in relatively small tanks or other vessels which do not require the specialized handling equipment necessary for larger and heavier containers. Propane, one of the preferred multi-purpose fuels, for example, is often transported and stored in tanks containing between about lO0 and 500 pounds.
In northern latitudes, temperatures frequently drop below -40C and often approach or exceed -50C. Since at such low temperatures a number of these gases cease to vaporize or have vaporization rates which are insufficient to maintain the desired gas pressure, heating devices are required. In the case of propane, vaporization rates become insufficient to pro-vide an adequate supply of propane gas as the temperature ap-proaches -40C. At approximately -42C, the vaporization rate of propane becomes zero and all appliances dependent on a steady supply of propane gas such as furnaces, cooking stoves, water heaters, etc~, become inoperative.
Heaters for large mostly stationary containers of the kind used in industrial and residential applications of fuels such as propane are known. Such heaters are in general inap-propriate for use with portable containers, because they mostly are designed to be semi-permanently fi~ed to a stationary tank, and they do not conform to the physical configurations of the portable tanks. Furthermore, the known heating devices generally generate too much heat so that they tend to create excessive and dangerous vapor pressure levels in the smaller containers and require a level of electrical energy which is found in ~972~
areas where commercial feeds are available, but which is seldom available from the very limited reser~es produced by the portable generating units used in most camps.
In an effort to vaporize sufficient fuel to run the necessary appliances in cold weather, users of portable fuel tanks have resorted to warming the tank with a battery heating blanket strapped onto the side of the tank. Generally these blankets produce more than enough heat, but lack ade~uate insulation, thus wasting scarce electrical energy. As such blankets are often cumbersome to secure to the tank, damage to the internal heating coils may occur-and cause the coils to burn out~ Moreove~, such blankets are often regulated by a thermostat which for reasons of safety is not usually acceptable in hazardous locations.
Various other methods for warming portable vessels have been employed such as the use of a light bulb covered by a cardboard box or a can~as, the use of a live flame, etc.
Besides being only temporary solutions, these methods are often quite hazardous.
It has now been found that a relatively small electrical heating device, also referred to as a "heat-patch", applied to a portion of the surface of a vessel containing a vaporizable liquid can produce the desired vapor pressure at the outlet of the vessel. The heating device according to the invention is not intended to heat an entire vessel and its contents, but rather to supply only enough warmth to promote the necessary vaporization. The heating device transmits heat only to a portion of the vessel surface and supplies only sufficient heat to cause liquid close to this portion of the surface to vaporize. The ~apor then l'bubbles" to the surface and becomes available for use.
The heating device according to the invention is designed for use with relatively small portable vessels of the kind used for transporting propane or other gases to remote locations. Such portable propane tanks often come in sizes of 100 or 420 pounds.
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Accordingly, the invention provides a portable electrical heating device adapted for spot-warming of a vessel containing vaporizable liquid. The heating device comprises:
a) an electrically and thermally insulating and weather-resistant backing including an inner surface, adapted to face a portion of a vessel surface, and an outer surface;
b) a self-limiting electrically resistive wire secured to the inner surface of the hacking; and c) means for removably attaching the heating device to a vessel surface.
The heating èlement is a commercially available self-limiting electrically resistive element which is adapted for use in hazardous locations. Such an element may be encased in a metal weave jacket and covered with plastic material.
At low temperatures the self-limiting element allows maximum conduction of electricity resuIting in high power output. As the temperature rises, the conduction of electricity and consequently, the output of the element decreases. As a result of this, the temperature drops allowing the power out-put of the element to increase again. In this way the element is self-limiting, providing, when in use, sufficient heat to promote vaporization of liquid in the vessel, while substan-tially avoiding potentially dangerous overheating as well as unnecessary consumption of electricity.
The self-limiting electrically resistive element is secured to a backing which is electrically and theremally insulating and which, at the same time, can withstand adverse weather conditions. The backing generally consists of an electrically and thermally insulating layer and a covering sheet. The covering sheet typically extends over all surfaces of the insulating layer which, when the heating device is attached to a vessel, are exposed to the weather. The element is attached to one surface, the inner surface~ of the insulating layer such that, when the heating device is secured ~ ~ y ~
to a vessel surface, the element is in contact with or proximate to the outside of the vessel. Maximum heat transfer is achieved when the element touches the vessel wall A distance between the element and the wall of a few thous-andths of an inch generally has iittle adverse effect, however,a distance of one eighth inch or more may resuIt in inadequate vaporization when high gas flow is required in very cold weather.
Between the element and the insulating material there may be a layer of r~flective material such as aluminum foil.
When the heating device is in use, this layer further assists in reducing heat loss to the outside. In this sase, the element is in contact with the reflective layer and may be held in place by tape such as reflective foil tape. The reflective material may e~tend over the entire inner surface of the backing or it may be in form of a strip which is wider than the element and which extends only below the element.
The heating device is either formed to fit a certain type and size of vessel or it is made sufficiently flexible to be adjustable to the curvature of various vessel walls.
The flexibility of the heating device will depend on the type and thickness of the backing. In either case, the heating device has to be sufficiently rigid to retain its shape once it is in place on the vessel.
The attachment means may ~e magnetic allowing the heating device to removably adhere to any vessel surface of ferrous material. The magnetic attachment means are preferably in the form of magnetic strips fastened to the heating device along the outside of the inner surface so that, when the strips are in contact with the vessel, the heating device adheres tightly to the vessel wall. Such magnetic strips advantageously consist of flexible plastic material impregnated with magnetized material. This flexibility allows the strips to readily conform to the curvature of the backing. The magnetic strips enhance the ~727'7 ~5--ease of removing the heating device from one vessel and reapplying it to another, since no straps, slots, supports, etc., are needed.
Alternatively, the heating device may also be attached to a vessel by straps or the like. In this way the heating device may be used with non-ferrous vessels. Pre~erably, the straps are flat elastic straps which extend around the vessel and are equipped with Velcro-type tTrademark) fasteners for ease of adjustment. In most cases it is desirable to install the heating device at the bas of the vessel wall.
The size of the heating device is largely governed by the size or length of ~he self-limiting element which, in turn, generally depends on the desired heat output. The siæe of the heating device need only be sufficient to accommodate the element and the attachment means.
~ hether the heating device is provided with magnetic attachment means or with straps or the like, it is easy to handle, and since the heating device is of compact shape it is readily movable from one location to another.
~0 The heating device is designed and constructed for outdoor use even in extremely cold temperatures. The heating element as well as the backing can withstand precipitation, wind, and many commonly used industrial oils, solvents and the like. Due to the self-limiting feature of the heating element temperature control is inherent in the element and does not depend on thermostats or the like. For this reason the heating device can be used on tanks containing potentially explosive substances. The insulating properties of the backing and the generally tight fit of the heat-patch on the vessel surface ensures that a high proportion of the generated heat is transmitted to the vessel. Energy efficiency and portability of the heating device as well as the fact that it can be used in potentially hazardous surroundings make the heating device particularly suitable for use in remote locations ~ith limited energy supplies.
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The present in~ention may more readily be understood by reference to the accompanying drawings which illustrate, by way of example, one preferred embodiment of the invention and in which Figure 1 is a perspective view of the outside of the heating device;
Eigure 2 is a perspective view of the surface of the heating device which is adapted to contact the vessel wall; and Figure 3 is a cross-section along lines III-III in Figure 2.
Figures 1 to 3 show a heating device or heating device 10 for use in adverse weather conditions such as in extreme cold. The heating device comprises heating element 30 secured to a backing 13, attachment strip 40 for attaching the heating device to the outside of a container 4, and a plug 36 for connecting the heating device to the electrical supply.
Heating element 30 is a self-limiting electrically resistive wire which is commercially available under the name 'IChemelex" (Trademark of Raychem Corporation). The element comprises bus wires in a self~limiting conductive core material, The core material is surrounded by jackets of insulating material, shielding metal and corrosion resistant plastic.
For the illustrated embodiment of the invention which is intended for use on a standard 420 pound propane tank two feet of Chemelex wire having an output of 6W/ft at 50F produces adequate heat to provide sufficient fuel even in very cold weather. As the wire is fairly rigid, the configuration of a reverse J proved to be convenient as well as efficient.
Element 30 is attached to a reflective layer of aluminum foil 20 with several strips of reflective adhesive tape 22~ In the illustrated embodiment, the element is J-shaped and is secured to the reflective layer 20 with aluminum foil tape which is substantially resistant to heat and minimizes heat loss since heat is readily transferred ,,
Northern exploration and deve:Lopment is expanding rapidly across the continent. In most cases, these activities are centered around isolated camps. In many of these camps, pro-pane and similar gases are used as fuel. Due to the remoteness of the locations and the need for camp portability such fuels are generally transported and stored in relatively small tanks or other vessels which do not require the specialized handling equipment necessary for larger and heavier containers. Propane, one of the preferred multi-purpose fuels, for example, is often transported and stored in tanks containing between about lO0 and 500 pounds.
In northern latitudes, temperatures frequently drop below -40C and often approach or exceed -50C. Since at such low temperatures a number of these gases cease to vaporize or have vaporization rates which are insufficient to maintain the desired gas pressure, heating devices are required. In the case of propane, vaporization rates become insufficient to pro-vide an adequate supply of propane gas as the temperature ap-proaches -40C. At approximately -42C, the vaporization rate of propane becomes zero and all appliances dependent on a steady supply of propane gas such as furnaces, cooking stoves, water heaters, etc~, become inoperative.
Heaters for large mostly stationary containers of the kind used in industrial and residential applications of fuels such as propane are known. Such heaters are in general inap-propriate for use with portable containers, because they mostly are designed to be semi-permanently fi~ed to a stationary tank, and they do not conform to the physical configurations of the portable tanks. Furthermore, the known heating devices generally generate too much heat so that they tend to create excessive and dangerous vapor pressure levels in the smaller containers and require a level of electrical energy which is found in ~972~
areas where commercial feeds are available, but which is seldom available from the very limited reser~es produced by the portable generating units used in most camps.
In an effort to vaporize sufficient fuel to run the necessary appliances in cold weather, users of portable fuel tanks have resorted to warming the tank with a battery heating blanket strapped onto the side of the tank. Generally these blankets produce more than enough heat, but lack ade~uate insulation, thus wasting scarce electrical energy. As such blankets are often cumbersome to secure to the tank, damage to the internal heating coils may occur-and cause the coils to burn out~ Moreove~, such blankets are often regulated by a thermostat which for reasons of safety is not usually acceptable in hazardous locations.
Various other methods for warming portable vessels have been employed such as the use of a light bulb covered by a cardboard box or a can~as, the use of a live flame, etc.
Besides being only temporary solutions, these methods are often quite hazardous.
It has now been found that a relatively small electrical heating device, also referred to as a "heat-patch", applied to a portion of the surface of a vessel containing a vaporizable liquid can produce the desired vapor pressure at the outlet of the vessel. The heating device according to the invention is not intended to heat an entire vessel and its contents, but rather to supply only enough warmth to promote the necessary vaporization. The heating device transmits heat only to a portion of the vessel surface and supplies only sufficient heat to cause liquid close to this portion of the surface to vaporize. The ~apor then l'bubbles" to the surface and becomes available for use.
The heating device according to the invention is designed for use with relatively small portable vessels of the kind used for transporting propane or other gases to remote locations. Such portable propane tanks often come in sizes of 100 or 420 pounds.
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Accordingly, the invention provides a portable electrical heating device adapted for spot-warming of a vessel containing vaporizable liquid. The heating device comprises:
a) an electrically and thermally insulating and weather-resistant backing including an inner surface, adapted to face a portion of a vessel surface, and an outer surface;
b) a self-limiting electrically resistive wire secured to the inner surface of the hacking; and c) means for removably attaching the heating device to a vessel surface.
The heating èlement is a commercially available self-limiting electrically resistive element which is adapted for use in hazardous locations. Such an element may be encased in a metal weave jacket and covered with plastic material.
At low temperatures the self-limiting element allows maximum conduction of electricity resuIting in high power output. As the temperature rises, the conduction of electricity and consequently, the output of the element decreases. As a result of this, the temperature drops allowing the power out-put of the element to increase again. In this way the element is self-limiting, providing, when in use, sufficient heat to promote vaporization of liquid in the vessel, while substan-tially avoiding potentially dangerous overheating as well as unnecessary consumption of electricity.
The self-limiting electrically resistive element is secured to a backing which is electrically and theremally insulating and which, at the same time, can withstand adverse weather conditions. The backing generally consists of an electrically and thermally insulating layer and a covering sheet. The covering sheet typically extends over all surfaces of the insulating layer which, when the heating device is attached to a vessel, are exposed to the weather. The element is attached to one surface, the inner surface~ of the insulating layer such that, when the heating device is secured ~ ~ y ~
to a vessel surface, the element is in contact with or proximate to the outside of the vessel. Maximum heat transfer is achieved when the element touches the vessel wall A distance between the element and the wall of a few thous-andths of an inch generally has iittle adverse effect, however,a distance of one eighth inch or more may resuIt in inadequate vaporization when high gas flow is required in very cold weather.
Between the element and the insulating material there may be a layer of r~flective material such as aluminum foil.
When the heating device is in use, this layer further assists in reducing heat loss to the outside. In this sase, the element is in contact with the reflective layer and may be held in place by tape such as reflective foil tape. The reflective material may e~tend over the entire inner surface of the backing or it may be in form of a strip which is wider than the element and which extends only below the element.
The heating device is either formed to fit a certain type and size of vessel or it is made sufficiently flexible to be adjustable to the curvature of various vessel walls.
The flexibility of the heating device will depend on the type and thickness of the backing. In either case, the heating device has to be sufficiently rigid to retain its shape once it is in place on the vessel.
The attachment means may ~e magnetic allowing the heating device to removably adhere to any vessel surface of ferrous material. The magnetic attachment means are preferably in the form of magnetic strips fastened to the heating device along the outside of the inner surface so that, when the strips are in contact with the vessel, the heating device adheres tightly to the vessel wall. Such magnetic strips advantageously consist of flexible plastic material impregnated with magnetized material. This flexibility allows the strips to readily conform to the curvature of the backing. The magnetic strips enhance the ~727'7 ~5--ease of removing the heating device from one vessel and reapplying it to another, since no straps, slots, supports, etc., are needed.
Alternatively, the heating device may also be attached to a vessel by straps or the like. In this way the heating device may be used with non-ferrous vessels. Pre~erably, the straps are flat elastic straps which extend around the vessel and are equipped with Velcro-type tTrademark) fasteners for ease of adjustment. In most cases it is desirable to install the heating device at the bas of the vessel wall.
The size of the heating device is largely governed by the size or length of ~he self-limiting element which, in turn, generally depends on the desired heat output. The siæe of the heating device need only be sufficient to accommodate the element and the attachment means.
~ hether the heating device is provided with magnetic attachment means or with straps or the like, it is easy to handle, and since the heating device is of compact shape it is readily movable from one location to another.
~0 The heating device is designed and constructed for outdoor use even in extremely cold temperatures. The heating element as well as the backing can withstand precipitation, wind, and many commonly used industrial oils, solvents and the like. Due to the self-limiting feature of the heating element temperature control is inherent in the element and does not depend on thermostats or the like. For this reason the heating device can be used on tanks containing potentially explosive substances. The insulating properties of the backing and the generally tight fit of the heat-patch on the vessel surface ensures that a high proportion of the generated heat is transmitted to the vessel. Energy efficiency and portability of the heating device as well as the fact that it can be used in potentially hazardous surroundings make the heating device particularly suitable for use in remote locations ~ith limited energy supplies.
., 27 ~
The present in~ention may more readily be understood by reference to the accompanying drawings which illustrate, by way of example, one preferred embodiment of the invention and in which Figure 1 is a perspective view of the outside of the heating device;
Eigure 2 is a perspective view of the surface of the heating device which is adapted to contact the vessel wall; and Figure 3 is a cross-section along lines III-III in Figure 2.
Figures 1 to 3 show a heating device or heating device 10 for use in adverse weather conditions such as in extreme cold. The heating device comprises heating element 30 secured to a backing 13, attachment strip 40 for attaching the heating device to the outside of a container 4, and a plug 36 for connecting the heating device to the electrical supply.
Heating element 30 is a self-limiting electrically resistive wire which is commercially available under the name 'IChemelex" (Trademark of Raychem Corporation). The element comprises bus wires in a self~limiting conductive core material, The core material is surrounded by jackets of insulating material, shielding metal and corrosion resistant plastic.
For the illustrated embodiment of the invention which is intended for use on a standard 420 pound propane tank two feet of Chemelex wire having an output of 6W/ft at 50F produces adequate heat to provide sufficient fuel even in very cold weather. As the wire is fairly rigid, the configuration of a reverse J proved to be convenient as well as efficient.
Element 30 is attached to a reflective layer of aluminum foil 20 with several strips of reflective adhesive tape 22~ In the illustrated embodiment, the element is J-shaped and is secured to the reflective layer 20 with aluminum foil tape which is substantially resistant to heat and minimizes heat loss since heat is readily transferred ,,
2~
through the tape to the vessel surface.
Reflective layer 20 is adhesively attached to a layer of a thermally and electrically insulating-material 15 which, in the illustrated embodiment, consists of polyurethane foam S of about two inches in thickness which is formed to fit the curvature of a standard 420 pound propane tan~.
All surfaces of the insulating material 15 except for the inner surface to which heating element 30 is attached are covered by a covering sheet 17. The covering sheet in the illustrated embodiment is made of polyvinyl chloride material which is substantially impermeable to precipitation as well as to many commonly used industrial oils and solvents and which is adhesively attached to the insulating material. The covering sheet, insultaing layer and reflecting layer form lS the bac~ing of the heating device.
The heating element 30 is connected to an electrical cord 35 which passes through a small opening in the backing to the outside where it is connected to a plug 36.
Magnetic strips 40 consisting of flexible plastic material impregnated with magnetized material are secured to the inner surface of the insulating layer along its perimeter.
In order to use the ~eating device 10 it merely has to ~e brought into contact with a vessel made of ferrous material. The magnetic strips 40 tightly adhere to the vessel wall 5 supporting the heat-patch on the vessel. In the embodiment illustrated in Figure 3, the heating element is in direct contact with the vessel. Generally the heating device is applied as close to the bottom of the vessel as convenient.
Once the element is connected to the electrical supply the element warms up the small area of the vessel wall which is close to ~he heating device t thereby causing the li~uid proximate to this part of the vessel wall to vaporize~ The vapor travels upwardly to the top of the vessel and fresh liquid comes into contact with the warm portion of the vessel wall. In this way a steady supply of gas is provided fGr use in appliances.
7;277 As the self-limiting heat:ing element warms up, its output of heat and use of electricity automatically decreases, thereby avoiding overheating as well as unneccessary use of energy. Similarly, as the heating element cools off again, its output increases, so as to ensure a steady supply of gas.
The insulating layer minimizes the loss of heat to the surrounding cold air and the weather-resistant covering sheet ensures that the insulating valué of layer 15 is not affected by precipitation, etc. Even though the use of a reflective layer as part of the backing of the heating device is not necessary to accomplish the object of the present invention, such a reflective layer further assists in rendering the heating device energy efficient.
The heating device can have any shape as long as it is compact, produces sufficient heat and allows efficient use of energy and tight fit to the respective vessel walls. Thus instead of being rectangular the heating device may be s~uare, circular, oval ox the like. Similarly, the desired length of the heating element may be arranged on the inner surface of the backing in any convenient way such as in the shape of a U, an open circle, a spiral, an open rectangle and the like Attachment of the heating element to the backing can be effected in any way which allows effic~ent exchange of heat between the heating element and the vessel wall and which contributes to the durability and ease of handling of the heating device.
The inner surface of the backing may be dished such that the periphery of the backing is in direct contact with the vessel wall, whereas the heating element is only in close proximity thereto.
The heating device can be secured to the vessel wall not only by magnetic strips or the like but also by way of straps, preferably elastic straps, which are fastened to the heat-patch and extend around the vessel. For convenience, such straps which may, for example, be about 5 cm in width, :
7~
and may be provided with Velcro type hook-and-loop fasteners.
Other suitable fasteners may be used as long as they allow the heating device to be attached to and detached from vessels with sufficient ease to render the heating device readily portable.
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through the tape to the vessel surface.
Reflective layer 20 is adhesively attached to a layer of a thermally and electrically insulating-material 15 which, in the illustrated embodiment, consists of polyurethane foam S of about two inches in thickness which is formed to fit the curvature of a standard 420 pound propane tan~.
All surfaces of the insulating material 15 except for the inner surface to which heating element 30 is attached are covered by a covering sheet 17. The covering sheet in the illustrated embodiment is made of polyvinyl chloride material which is substantially impermeable to precipitation as well as to many commonly used industrial oils and solvents and which is adhesively attached to the insulating material. The covering sheet, insultaing layer and reflecting layer form lS the bac~ing of the heating device.
The heating element 30 is connected to an electrical cord 35 which passes through a small opening in the backing to the outside where it is connected to a plug 36.
Magnetic strips 40 consisting of flexible plastic material impregnated with magnetized material are secured to the inner surface of the insulating layer along its perimeter.
In order to use the ~eating device 10 it merely has to ~e brought into contact with a vessel made of ferrous material. The magnetic strips 40 tightly adhere to the vessel wall 5 supporting the heat-patch on the vessel. In the embodiment illustrated in Figure 3, the heating element is in direct contact with the vessel. Generally the heating device is applied as close to the bottom of the vessel as convenient.
Once the element is connected to the electrical supply the element warms up the small area of the vessel wall which is close to ~he heating device t thereby causing the li~uid proximate to this part of the vessel wall to vaporize~ The vapor travels upwardly to the top of the vessel and fresh liquid comes into contact with the warm portion of the vessel wall. In this way a steady supply of gas is provided fGr use in appliances.
7;277 As the self-limiting heat:ing element warms up, its output of heat and use of electricity automatically decreases, thereby avoiding overheating as well as unneccessary use of energy. Similarly, as the heating element cools off again, its output increases, so as to ensure a steady supply of gas.
The insulating layer minimizes the loss of heat to the surrounding cold air and the weather-resistant covering sheet ensures that the insulating valué of layer 15 is not affected by precipitation, etc. Even though the use of a reflective layer as part of the backing of the heating device is not necessary to accomplish the object of the present invention, such a reflective layer further assists in rendering the heating device energy efficient.
The heating device can have any shape as long as it is compact, produces sufficient heat and allows efficient use of energy and tight fit to the respective vessel walls. Thus instead of being rectangular the heating device may be s~uare, circular, oval ox the like. Similarly, the desired length of the heating element may be arranged on the inner surface of the backing in any convenient way such as in the shape of a U, an open circle, a spiral, an open rectangle and the like Attachment of the heating element to the backing can be effected in any way which allows effic~ent exchange of heat between the heating element and the vessel wall and which contributes to the durability and ease of handling of the heating device.
The inner surface of the backing may be dished such that the periphery of the backing is in direct contact with the vessel wall, whereas the heating element is only in close proximity thereto.
The heating device can be secured to the vessel wall not only by magnetic strips or the like but also by way of straps, preferably elastic straps, which are fastened to the heat-patch and extend around the vessel. For convenience, such straps which may, for example, be about 5 cm in width, :
7~
and may be provided with Velcro type hook-and-loop fasteners.
Other suitable fasteners may be used as long as they allow the heating device to be attached to and detached from vessels with sufficient ease to render the heating device readily portable.
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Claims (12)
1. A portable electrical heating device adapted for spot-warming of a vessel containing pressurized liquid and vapor phases, said device comprising:
a) an electrically and thermally insulating and weather-resistant backing including an inner surface adapted to face a portion of a vessel wall;
b) a self-limiting electrically resistive element secured to the inner surface of the backing and adapted to be in heat-transfer relation to a portion of a vessel wall;
c) the backing including a layer of electrically and thermally insulating material defining said inner surface and to which the self-limiting element is secured, and a covering sheet of weather-resistant material covering outwardly directed surfaces of the insulating layer;
d) the backing further including a reflective layer disposed on said inner surface between the insulating layer and the self-limiting element;
e) means for removably attaching the heating device to a vessel wall, so as to spot-warm a portion of the vessel wall and heat liquid phase in proximity thereto at least to its boiling point.
a) an electrically and thermally insulating and weather-resistant backing including an inner surface adapted to face a portion of a vessel wall;
b) a self-limiting electrically resistive element secured to the inner surface of the backing and adapted to be in heat-transfer relation to a portion of a vessel wall;
c) the backing including a layer of electrically and thermally insulating material defining said inner surface and to which the self-limiting element is secured, and a covering sheet of weather-resistant material covering outwardly directed surfaces of the insulating layer;
d) the backing further including a reflective layer disposed on said inner surface between the insulating layer and the self-limiting element;
e) means for removably attaching the heating device to a vessel wall, so as to spot-warm a portion of the vessel wall and heat liquid phase in proximity thereto at least to its boiling point.
2. A device as in claim 1 wherein power output of the self-limiting element decreases in response to increasing ambient temperature and increases with decreasing temperature.
3. A device as in claim 1 wherein power output of the self-limiting element is inversely proportional to the temperature of the portion of the vessel wall with which the element, in use is in heat-transfer relation.
4. A device as in claim 1 wherein the attachment means are magnetic means adapted to removably adhere the heating device to a vessel wall made of ferrous material.
5. A device as in claim 4 wherein the magnetic means are strips of magnetic material secured to the perimeter of the inner surface of the backing.
6. A device as in claim 1 wherein the attachment means are elastic straps adapted to removably secure the heating device to a vessel wall.
7. A device as in claim 1 wherein the reflective layer is aluminum foil.
8. A device as claimed in claim 1 wherein the heating device is of arcuate shape such that, when attached to a portion of a vessel wall, the heating device closely corresponds to the shape of the respective wall portion.
9. A device as claimed in claim 2 wherein, when the heating device is attached to a portion of a vessel wall, the self-limiting element and the peripheral edge of the backing are in contact with the vessel wall.
10. A device as in claim 1 wherein the self-limiting element is arranged in the shape of a letter U with legs of uneven lengths.
11. A device as in claim 1 wherein the heating device is sufficiently flexible to adapt to the curvature of a vessel wall when being attached thereto.
12. A device as claimed in claim 1 wherein an electrical connection, adapted to be connected to an electrical supply, passes from the self-limiting element through the backing to the outside.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000421443A CA1197277A (en) | 1983-02-11 | 1983-02-11 | Propane tank warmer |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000421443A CA1197277A (en) | 1983-02-11 | 1983-02-11 | Propane tank warmer |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1197277A true CA1197277A (en) | 1985-11-26 |
Family
ID=4124552
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000421443A Expired CA1197277A (en) | 1983-02-11 | 1983-02-11 | Propane tank warmer |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1197277A (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4912303A (en) * | 1989-02-17 | 1990-03-27 | Beavers Allan E | Electric heating belt for liquid propane bottles |
| EP0407027A2 (en) * | 1989-05-26 | 1991-01-09 | Shinko Pantec Co., Ltd. | Method for repairing glasslined equipments by sol-gel process |
| FR2656682A1 (en) * | 1990-01-03 | 1991-07-05 | Electricite De France | DEVICE AND METHOD FOR PROTECTION AGAINST CORROSION OF A CALORIFIED METAL ENCLOSURE. |
| SE2151413A1 (en) * | 2021-11-22 | 2023-05-23 | Husqvarna Ab | Control unit and method for a gas tank heating arrangement on a concrete surface processing machine |
| WO2023091064A1 (en) * | 2021-11-22 | 2023-05-25 | Husqvarna Ab | Control unit and method for a gas tank heating arrangement on a concrete surface processing machine |
-
1983
- 1983-02-11 CA CA000421443A patent/CA1197277A/en not_active Expired
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4912303A (en) * | 1989-02-17 | 1990-03-27 | Beavers Allan E | Electric heating belt for liquid propane bottles |
| EP0407027A2 (en) * | 1989-05-26 | 1991-01-09 | Shinko Pantec Co., Ltd. | Method for repairing glasslined equipments by sol-gel process |
| EP0407027A3 (en) * | 1989-05-26 | 1991-01-30 | Shinko Pantec Co., Ltd. | Method and apparatus for repairing glasslined equipments by sol-gel process |
| FR2656682A1 (en) * | 1990-01-03 | 1991-07-05 | Electricite De France | DEVICE AND METHOD FOR PROTECTION AGAINST CORROSION OF A CALORIFIED METAL ENCLOSURE. |
| EP0438941A1 (en) * | 1990-01-03 | 1991-07-31 | Electricite De France | Device and method for preventing corrosion of a metallic insulated casing |
| SE2151413A1 (en) * | 2021-11-22 | 2023-05-23 | Husqvarna Ab | Control unit and method for a gas tank heating arrangement on a concrete surface processing machine |
| WO2023091064A1 (en) * | 2021-11-22 | 2023-05-25 | Husqvarna Ab | Control unit and method for a gas tank heating arrangement on a concrete surface processing machine |
| SE545342C2 (en) * | 2021-11-22 | 2023-07-11 | Husqvarna Ab | Control unit and method for a gas tank heating arrangement on a concrete surface processing machine |
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