CA1245261A

CA1245261A - Device for thawing frozen lines

Info

Publication number: CA1245261A
Application number: CA000483250A
Authority: CA
Inventors: Ernest Chretien
Original assignee: Individual
Current assignee: Individual
Priority date: 1985-06-05
Filing date: 1985-06-05
Publication date: 1988-11-22

Abstract

ABSTRACT
A heater for use in thawing frozen plastic water pipes has an apertured housing with rounded ends which may be manipulated along a pipe. The housing contains heating elements mounted on insulating supporting plates. The plates are formed with further apertures to promote circulation of liquid and improved heat transfer to the plastic pipe. The heat dissipation of the heater is less than that necessary to melt the plastic pipe in the absence of liquid.

Description

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I'he present invention relates to a heater for use in thawing frozen plastic water pipes. In this application the term "water pipe" is intended to include both supply and return pipes and pipes carrying waste water such as sewage lines.
It is known to use electric heating to thaw frozen water pipes. U.S. Patent No. 2,516,950 issued August 1, 1950 to Bragy shows a heater suitable for use with metallic water pipes consisting of a sealed heating unit advanced into the water pipe by means of the metallic conduit sheathing the power cable. U,S. Patent No.
3,519,023, issued July 7, 1970 to Burns ee al. sliows the use of an external collar for defrosting pipes. U.S.
Patent No. 3,900,0~7, issued August 19, 1975 to Heppell deals with the thawing of plastic pipe and teaches the use of an internal conductor permanently formed on the pipe.
Clearly, the thawing of plastic pipe raises additional problems in that overheating can cause sub-stantial damage to the pipe itself. The device of the present invention provides a specific amount of heat dissipation for any particular situation which is such that it will not melt the plastic pipe, even in -the absence of liquid, or burn out by i-tself. By making the device of this invention of the immersion type, heat is conveyed from the heater to the plastic pipe by the melted liquid.
Further, the hot water generated by the heater rises and can thus operate ahead of or behind the lo_ation of the heater.

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Specifically, the present invention relates to a heater for use in thawing a frozen plastic water pipe, comprising an apertured housing with rounded ends, whereby liquid in the pipe may enter the apertures. ~n electrical heating element is carried by an insula-ting plate suppor-ted within the housing and terminal means are positioned on the insulating plate adjacent the rear end of the housing for connecting the heating element to a source of electrical power. The heat dissipation of the heating element is less than that necessary to melt the plastic pipe in the absence of liquid.

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~Z~52~i1 Particular embodiments of the invention will now be described in conjunction with the accompanying drawings, in which:
Figures lA, lB and lC are front, side and rear views, respectively, of a heating device useful to be manipulated around bends in larger diameter pipes, such as sewage lines;
Figures lD, lE and lF are corresponding views with the housing shown in phantom;
Figures 2A, 2B and 2C are front, side and rear views, respectively, of a heating device using a coiled tubular element;
Figures 2D, 2E and 2F and Figures 2G, 2H and 2I
are corresponding views with the housing shown in phantom;
Figures 3A, 3B and 3C are front, side and rear views, respectively, of a heating device useful in low wattage applications;
Figures 3D, 3E and 3F are corresponding views with the housing shown in phantom;
Figures 4A, 4B and 4C are front, side and rear views, respectively, of a heating device useful in higher wattage applications; and Figures 4D, 4E and 4F are corresponding views with the housing shown in phantom.

Figure 1 show~ a heater in which the housing 10, preferably made of copper is of relatively stub configuration, the length being less than twice the diameter. This is kh/

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intended for use with relatively large plastic lines such as are used for sewage. The configuration of the heater enables it to be manipulated around bends in the line.
Typically, it will be 4" long and 2~" in diameter. The housing is formed in two sections detachably connected by screws 11. This enables the heating element to be easily changed deper.ding on the wattage required or in the event of failure. Housing 10 is formed with apertures 12 permitting liquid in the line to be thawed,to enter the housing and thereby facilitate heat transfer.
The heating element contained in housing 10 consists of asbestos cards or plates 13 arranged in a cross configuration with stainless steel resistance wire 14 wound therearound.
A shoulder 15 is formed in the asbestos cards so that they are held in position between the two portions of the housing.
The wire 1~ forms an inner and outer winding to provide a relatively high wattage heater. The inner winding passes through apertures 16 formed in the insulating cards. These apertures also permit circulation of liquid in the heater and thus promote heat transfer. Terminals 17 are provided whereby the heating element can be connected to a source of electrical power through an insulated conductor, not shown.
Figure 2 shows another embodiment of a heating device in accordance with the present invention. The housing 20 is of more elongated configuration, typically of copper and of length 6" and diameter 1". Again, apertures 22 are formed in the housing to permit liquid in the pipe to be thawed,to reach the heating element.

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The single insulating plate 23 carries a tubular coiled heating element 24 passing through apertures 25.
The apertures permit circulation of the liquid inside the housing to promote heat transfer. Terminals 27 are provided for connection to an insulated conductor supplying the necessary electrical power.
Figure 3 shows a different embodiment of a heater for low wattage applications in accordance with the present invention. The copper housing 30 again is of elongated configuration, typically of length 10" and diameter 11". The apertures 32 are smaller than in the heaters shown in Figures 1 and 2.
The heating element is formed on asbestos cards 33 arranged in a cross configuration and consists of a single winding 34 of stainless steel wire terminating in terminals 37. It will be noted that no apertures are formed in the asbestos cards 33 since in -this low wattage application there is no requirement for enhanced circulation.
Figure 4 shows a heater similar to that of Figure 3 but adapted for higher wattage applications. Housing 40 is of elongated configuration, typically formed of copper, with length 9" and diameter 2". Rows of apertures 42 are formed in the housing. The heating element consists of stainless steel wire 44 wound on asbestos cards 43 arranged in a cross configuration. Apertures 46 are provided in the asbestos cards to promote circulation of the liquid from the pipe to be thawed and hence increase heat transfer. Terminals 47 are provided for wire 44.

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Thus, there have been disclosed heaters for thawing frozen plastic water pipes which operate as immersion type devices. The hot water ~enerated by the heater rises and, thus, can operate ahead of or behind the location of the heater. The heaters are advanced towards the frozen section of the pipe by means of a rubber covered, insulated power line. Some embodiments can be manipulated around bends in the line. In all cases, the heat generated by the heater is selected to be less than that which would melt the plastic pipe under the worst conditions, i.e. in the absence of liquid. Clearly, the invention is not restricted to ~he particular dimensions and confi~urations shown.

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Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY OR
PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A heater for use in thawing a frozen plastic water pipe and movable along the interior of the pipe, comprising an apertured housing with rounded ends, whereby liquid in the pipe may enter the apertures, an electrical heating element carried by an insulating plate supported within the housing, terminal means positioned on the insulating plate adjacent the rear end of the housing for connecting the heating element to a source of electrical power, the heat dissipation of the heating element being less than that necessary to melt the plastic pipe in the absence of liquid.

2. A heater for use in thawing a frozen plastic water pipe and movable along the interior of the pipe, comprising an apertured housing with rounded ends, whereby the housing may be manipulated around bends in the pipe and liquid in the pipe may enter the apertures, an electrical heating element wound on an insulating plate supported within the housing, said insulating plate being formed with further apertures to promote circulation and transfer of heat to liquid entering by the apertures in the housing, terminal means positioned on the insulating cord adjacent the rear end of the housing for connecting the heating element to a source of electrical power, the heat dissipation of the heating element being less than that necessary to melt the plastic pipe in the absence of liquid.

3. A heater as set out in claim 2 wherein the length of the housing is less than twice the diameter.

4. A heater as set out in claim 1 or claim 2 wherein a pair of insulating plates are provided arranged in a cross configuration and the heating element comprises a wire wound around the extremities of the cross.

5. A heater as set out in claim 1 or claim 2 wherein the heating element is a coil encased in a tube, the tube extending through apertures in the insulating plate.

6. A heater as set out in claim 1 or claim 2 wherein the housing is formed with a removable cap permitting the heating element to be changed.