US 3331946 A
Description (OCR text may contain errors)
July 18, 1967 J. E. 5mm 3,331,946
ELECTRIC PIPE HEATER Filed 001;. 8, 1964 l/CY/YYQJ f. [SO/bro mvsmon ATTORNEVJ United States Patent 3,331,946 ELECTRIC PIPE HEATER James E. Bilbro, Houston, Tex., assignor to Thermon Manufacturing Co., a corporation of Texas Filed Oct. 8, 1964, Ser. No. 402,543 2 Claims. (Cl. 219535) ABSTRACT OF THE DISCLOSURE Heat transfer apparatus including a channel member with heat transfer material disposed therein prior to mounting on a pipe or similar structure, wherein a heat conductor element is disposed in the heat transfer material without air gaps and the entire assembly is clamped on the pipe for improving the transfer of heat between the heat conductor element and the pipe.
Background of the invention In United States Patent No. 2,982,992, an applicator apparatus for applying heat transfer material in a puttylike or plastic condition is disclosed.
Summary of the invention The present invention includes a heat transfer material which is preformed in a channel member and which improves heat transfer rather than serving as an insulator. A heat conductor element or elements such as electrical resistance wires are embedded in the heat transfer material. The channel member is clamped onto the pipe so that its longitudinal edges engage the external surface of the pipe, whereby the heat transfer material and heat conductor element are confined to prevent a loss of the heat transfer material and the formation of air gaps in such material during the use of the apparatus.
It is therefore an object of this invention to provide an applicator for heat transfer material which is an improvement on the apparatus of United States Patent No. 2,982,- 992 in that it is prefabricated so as to facilitate application of the heat transfer material and so as to provide an improved final installation of such material.
An important object of this invention islto provide a new and improved heat transfer apparatus which is adapted to apply an evenly distributed covering of a heat transfer material on electrical heating wires, steam tracing, and the like whereby gaps in such material are avoided.
Another object of this invention is to provide a new and improved heat transfer apparatus which is adapted to apply the heat transfer material in a plastic condition and which may be immediately used after installation without delaying for a curing or solidifying of the heat transfer material.
A particular object of this invention is to provide a new and improved heat transfer apparatus wherein heat transfer material in a plastic condition is packaged in a channel member and is adapted to be pressed over a heating and/ or cooling element or elements and thereafter secured by bands or other holding means to a pipe, plate or other object to be heated or cooled by the heating and/ or cooling element or elements, whereby an installation is obtained in which no air spaces or gaps in the heat transfer material occur.
A specific object of this invention is to provide a new and improved heat transfer apparatus wherein electrical heating wires are embedded in a heat transfer material which is confined on an object by a channel member.
Still another object of this invention is to provide a new and improved prefabricated package for heat transfer material and applicator wherein a pair of applicators are assembled together, and wherein the heat transfer material is protected from contamination.
The preferred embodiment of this invention will be described hereinafter, together with other features thereof, and additional objects will become evident from such description.
The invention will be more readily understood from a reading of the following specification and by reference to the accompanying drawings forming a part thereof, where in an example of the invention is shown, and wherein:
FIG. 1 is a view, partly in elevation and partly in section, illustrating the heat transfer apparatus of this invention when mounted on a pipe for use;
FIG. 2 is a vertical sectional view taken on line 22 of FIG. 1;
FIG. 3 is a vertical sectional view illustrating a package for facilitating the use of a prefabricated applicator of this invention;
FIG. 4 is a vertical sectional view illustrating a modified shape for the channel member of the prefabricated applicator of this invention prior to the insertion of the wires or other heat conductor element therein;
FIG. 5 is a view similar to FIG. 4, but illustrating another modification of the channel member of the prefabricated applicator of this invention;
FIG. 6 is a vertical sectional view similar to FIG. 4, but illustrating a further modification of the shape of the channel member of the prefabricated applicator; and
FIG. 7 is also a vertical sectional view illustrating still another modification of the shape of the channel member for the prefabricated applicator of this invention.
In the drawings, the letter A designates generally the heat transfer apparatus of this invention. Such apparatus A is adapted to be mounted on and secured to an object to be heated or cooled such as indicated by the pipe P. Briefly, the heat transfer apparatus A includes a prefabricated applicator which is adapted to be positioned over a heat conductor element or elements H, whereby heating or cooling with such elements H may be effectively accomplished, so as to transfer heat to or from fluid or other material within the pipe P or other object to which the heat transfer apparatus A is attached.
Considering the invention more in detail, the heat transfer apparatus A includes a channel member 10 which is formed of steel, rigid plastic or other relatively rigid material. Such channel member 10 may take numerous shapes as will be more evident hereinafter, but in each instance, the channel member 10 is provided with a longitudinal channel such as indicated at 1001 (FIGS. 2 and 3). In the form of the invention illustrated in FIGS. 1-3, the channel member 10 is semi-cylindrical in shape so that the channel 104: is a convex groove which terminates in longitudinally extending edges 10b.
The length of the channel member 10 may be substantially the same as the length of the heat conductor element or elements H, or in some instances, the channel member 10 may be formed by a plurality of relatively short lengths as compared to the length of the element or elements H which are joined together when applied to the pipe P or other object to be heated or cooled so as to completely cover that portion of the element H extending along the pipe P or other object.
To facilitate the installation of the heat transfer apparatus A on the pipe P or other object, it is preferable to provide a prefabricated applicator which includes the channel member 10 and heat transfer material 12 disposed therein (FIG. 3). The heat transfer material 12 is preferably of the type sold under the trademark Thermon, which is a material that is in a putty-like state or plastic condition at normal room temperatures. Such material may be thermosetting and therefore adapted to harden upon the application of heat, or it may be nonhardening. By way of example, such heat transfer material may have the following components in the percentages by weight indicated: polybutene 50%; 4,4 methylene bis (2,6 di-tert-butylphenol).5% pyrogenic colloidal silica (sold under the trademark Cab-o-Sil)2.0%; and graphite47.5%. Various organic binders may be used instead of the polybutene, such as butyl rubber and uncatalyzed epoxy resin or silicone and such organic binder may be present in an amount of from about 40 to about 60% by weight. In place of the 4,4 methylene bis, hydroquinone may be used, preferably in an amount of about .05 Instead of the graphite, other metals in powdered granular or particulate form, metal oxides or other metallic compounds and any form of divided carbon may be used, either by themselves or in a mixture of one or more of such heat conducting agents.
To facilitate the storage and handling of the prefabricated applicator of this invention, the package illustrated in FIG. 3 may be employed wherein a pair of such prefabricated applicators is mounted together with the heat transfer material 12 in engagement with a separator strip 14 formed of a silicone sheet or a polyethylene sheet or of some similar material which is readily releasable from the heat transfer material 12 and the channel members 10. With the package illustrated in FIG. 3, the heat transfer material 12 is protected against contamination by foreign objects while in storage and is prevented from being exposed until ready for actual use.
In the preferred embodiment, the heating element or elements H is in the form of a pair of electrical wires 20 and 21 which are preferably carried as a unit in a layer of insulation or other covering 22. Normally, each of the electrical wires 20 and 21 is provided with a sleeve of insulating material and an outer covering of metallic wire braid is used to form the composite heating element H. Such wire braid is indicated in FIG. 1 at 22.
In any event, in the final installation of the heat transfer apparatus A, the heat conductor element H is embedded in the heat transfer material 12 with both disposed on the pipe P or other object to be heated or cooled as best seen in FIGS. 1 and 2. The longitudinal edges b of the channel member 10 rest in contact with the external surface of the pipe P or are substantially in contact therewith so that the heat transfer material 12 surrounds the heating element or elements H and eliminates any air spaces between the heating element Hand the pipe P, thereby assuring an effective transfer of heat to or from the heating element or elements H to the pipe P and the contents thereof.
The channel .member 10 is secured to the pipe P by longitudinally spaced bands or straps 30 formed of metal or any other material such as plastic. The straps or bands 30 are preferably locked around the pipe P and the channel member 10 by any type of crimped locking element 31 or other suitable means for accomplishing a locking of the strap or band in the encircling position to thereby secure the channel member 10 firmly on the pipe P. In FIG. 1, the locking element 31 is shown with suitable crimps 31a which are of a conventional construction for clamping bands.
In the use of the form of the invention illustrated in FIGS. 1-3, the prefabricated package shown in FIG. 3 is first assembled for storage or transportation to the point of use. The length of the channel members 10 may vary, as previously pointed out, but normally they will be substantially co-extensive with the length of the heat conductor elements H which are to be employed therewith. At the point of installation, the heat transfer apparatus A may be applied to a pipe P or to any fiat or other type of surface. As illustrated in FIGS. 1 and 2, the object to be heated is a pipe P and the heat conductor element H is a pair of electrical heating wires and 21 which are of course suitably connected to a source of electrical current 'for resistance type heating. In other instances, the heat In any event, the heating or cooling element or elements H are embedded in the heat transfer material 12 by pressing the heat transfer applicator downwardly on top of such element or elements H to embed or substantially cover the element or elements H. In that way, all air spaces are eliminated around the element H and a very efficient heat transfer is obtained. The presence of the channel member 10 prevents any shifting of the heat transfer material 12 and assures its proper application around the element or elements H.
When the channel member 10 is thus in place on the pipe P or other object, the channel member 10 is secured in place by the clamping bands or straps 30 or other suitable securing means. With such construction, the heating or cooling elements H can be immediately used, whether the material 12 is thermosetting or non-hardening, the channel 10 serves to prevent harmful movement of the elements H and the material 12 relative to each other and the pipe P. When the heat transfer material 12 is a thermosetting material, it may be hardened by transmitting heat through the element or elements H so that the heat transfer material 12 becomes a relatively hard material permanently locking the electrical wires or other heating elements H to the pipe P. In this connection, it should be noted that when the heat conductor elements H are electrical wires 20 and 21, the channel member 10 is of particular importance since it prevents any movement of the heating elements when they expand due to the resistance heating. In other words, if the electrical wires are placed in a heat transfer material, or are simply covered by a heat transfer material, and allowed to heat up, they will expand prior to the time the heat transfer material has hardened and this will result in local areas of expansion, causing air spaces and consequent over-heating of the wires at such air spaces. The presence of the channel member 10 and the securing bands 30 prevents any such over-heating due to local areas of expansion of the heater wires.
Also, it should be noted that use of the channel member 10 provides a prefabricated applicator which assures an even distribution of the heat transfer material 12 with respect to the heating element or elements H so as to avoid leaving any air gaps or uneven areas around the heating element or elements H to again assure against the over-heating at localized areas which might otherwise occur.
In FIGS. 4, 5, 6 and 7, different shaped channel members 110, 210, 310 and 410 are illustrated, each of which has its inner channel filled with a heat transfer material 12. The modifications of FIGS. 4-7 are illustrated to make it clear that the invention is not limited to any particular shape of the channel member 10 since each of the modifications of FIGS. 4-7 may be employed in the heat transfer apparatus A instead of the semi-cylindrical channel member 10 of FIGS. 1-3.
The foregoing disclosure and description of the invention is illustrative and explanatory thereof and various changes in the size, shape and materials, as well as in the details of the illustrated construction, may be made within the scope of the appended claims without departing from the spirit of the invention.
What is claimed is:
1. Heat transfer apparatus, comprising:
(a) a pipe adapted to be heated;
(b) a channel member having a pair of longitudinally extending edges and a longitudinal cavity formed between said edges;
(c) a heat conductor element extending longitudinally within said cavity;
'(d) heat transfer material disposed and filling all of the space in said cavity except for the portion occupied by said heat conductor element;
(e) said heat transfer material and said channel member being preformed and disposed as a unit on said (f) said longitudinal edges of said channel member engaging the curved longitudinal surface of said pipe;
(g) said heat transfer material including a heat conducting agent for increasing the heat transfer between said heat conductor element and said pipe as compared to the heat transfer with the heat conductor element alone; and
(h) a plurality of clamping bands encircling said pipe and said channel member to hold said longitudinal edges of said channel member in contact with the external curved surface of said pipe for preventing the formation of air gaps in the heat transfer material between the heat conductor element and the pipe and for maintaining an increased heat transfer between the heat conductor element and the pipe.
2. The structure set forth in claim 1, wherein:
(a) said heat conductor element includes a pair of electric resistance heating wires.
6 References Cited UNITED STATES PATENTS 2/1917 Heller 219-436 5/1922 Stranszky 219-544 X 3/1928 Hynes 219-535 X 5/1942 Place 219-544 X 1/ 1957 Palmer. 4 11/1957 Fulham 219-535 X 5/1961 Brown et al 219-535 X 10/1965 Indoe 219-535 X FOREIGN PATENTS 7/1921 Sweden.
ANTHONY BARTIS, Primary Examiner.