US1468106A - Electric heater - Google Patents

Description

Sept. 18 1923. 1,468,106 v w. s. HADAWAY, JR

ELECTRIC HEATER 3 vwewfoz MM; M

WMQ-MW Sept..18, 1923.

W. S. HADAWAY, JR

ELECTRIC HEATER Original Fi 1ed na 23, .1917 2 Sheets-Sheet 2 a nve'wl'oz a attorney; 3% WM +-M Patented Sept. 18, 1923- UNITED, STA

WILLIAM S. HADAWAY, JR, OF NEW ROCHELLE, NEW YORK.

ELECTRIC HEATER.

Application filed Kay 23, 1917, Serial No. 170,859. 7 Itenewed August 5, 1921. Serial No. 490,109.

To all whom it may concern:

'Be it known that 1, WILLIAM S. Hana- WAY, J r., a citizen of the United States, and a resident of New Rochelle, county of vWestchester, and State of New York, have invented certain new and useful Improvements. in Electric Heaters, of which the following is a specification, reference being had to the accompanying drawings, forming a part thereof. .s

My invention relates to electric heaters and heater units or structures and it has special reference to such as are adapted and intended to be put to a wide variety of uses without material change in the structure of the heater. In other words, my invention has reference to a heater element or fundamental member which leads itself to general use in the arts.

One object. of m invention is to provide a heater element 0 the aforesaid character, that shall be adapted to' utilize effectively both alow cost source of heat such as lowpressure steam, and, a'relatively high cost 2 source such as electricity.

.Another object is to concentrate the heat at any particular part or portion of the I heater and to minimize the heat losses when the device is in service.

Another object is to provide a heating element that shall not onl rugged like the armore type as hitherto constructed, but furthermore one in which the necessity for high pressure between the heat generating element, its insulation and the sheath is avoided and the heat is transferred to the sheath by a particularly effective medium which is not hindered by the electrical insulation disposed between the generating element and the sheath.

. The requirements of the design of an electric heater suitable for use on a circuit of ordinary voltage, are such that it is very diflicult and often expensive to produce a '46 heater which effectively supplies heat to a small area such as the point of a small soldering iron or the end of abranding tool or the like, and low voltage windings have been employed in some cases, the line voltage being reduced by translating devices such as transformers, motor generators, etc.

be mechanically- It has been my aim to provide a heater,

element that shall automatically build up its seat to ahigh temperature and concentrate it at a small area, at one end for example, without the use of a translating device such as a transformer or other means for applying low voltage current to the heater. i

In order that my invention may be thoroughly understood 1 Will now proceed to describe the same in the'following specification, and then point out the novel features thereof in appended claims.

Referring to the drawings:

Figure 1 is an elevation of a heater element or unit constituting an embodiment of my invention.

Figure 2 is a longitudinal section of the same unit as adapted to the use of a'branding tool or iron but drawn to a relatively large scale to show the details of the structure.

An end view of the same is shown in Figure 3. v

Figure 4 is a transverse "section on the line 4-F4 of Figure 2.

1 working ends of the heater units modified for use as a soldering tool and as a cautery. Figure 7 corresponds 'to Figure 2 and shows a modified structure which also constitutes an embodiment of my invention. Figure 8 is a section taken on the line 88 of Figure 7 One of the .units is shown as adapted for use as a pyrographicinstrument in Figure 9. 4 Figure 10 is a bottom plan view, the handle and casing omitted, of a, laundry iron provided with the heater units or elements of my invention.

Figure 11 is a sectional elevation of the same men. I i I Figure 12 is a partially sectional plan view of the iron, with the electric circult connections shown diagrammatically.

Figure 13 shows one of the heaters as applied to the iron, in longitudinahsection, and I Figure 14 shows the same heater in transverse section. v

res 5 and 6 are sections showing the.-

- is supplied from the conductor 17 for ex Figure 15 corresponds to Figure 2, and shows still another modification of my invention.

Special reference may first be had to Figures 1 to 1 inclusive, from which it appears that the unit or heater element comprises an elongated tubular casing or armor 10 of metal, an inner tubular member 11 which is substantially coextensive with the casing, and is smaller in diameter being spaced therefrom by an insulating granular mass 12 which may be composed of particles of carborundum. Within the inner tube is an electric heating coil 13 which is connected at the working end of the device to the inner tube 11, and is separated from the inner tube throughoutits length by finely divided insulating particles 1 which may constitute a porous or granular mass similar to the mass 12.

The coil may extend the entire length of the structure but it may be preferable in many cases to make it somewhat shorter than the tubes and locate it adjacent to the working end of the device which is designated 15. in the structure illustrated in Figures 1 to i, the working member is formed into .a branding die 16.

The tube 11 constitutes one of the electrical terminals of the device, a supply circuit conductor 17 being connected thereto. The terminal 18 or" the coil 13 constitutes the other terminal of the device and is connected to a supply circuit conductor 19. The inner tube 11 extends slightly beyond the casing and is connected to a pipe 20 through which low temperature steam or other suitable fluid is supplied to the device.

The unit, as already explained, will usually be long relative to its diameter and as hereinafter explained, it may be bent into any convenient form such as a helix or spiral in' order that it may be more compact and better adapted for use in the arts.

When the device is in use, electric energy ample, thrhugh the tube 11 in which more or less heat is generated, thence through the c011 13 in which a large proportion of the heat is generated, then through the terminal 18 to the conductor 19. The fluid supplied to the unit may be a permanent gas as air, but I prefer to utilizelow pressure steam which may enter for example, at a temperature of 225 F;

This steam percolates through the porous mass 14 formed by the granular particles within the inner tube and heats the mass to its own temperature. iAs the steam pro-.

gresses its temperature is very materially increased by taking up the heatgenerated in the coil 13 and 111 the tube 11. This heat is cumulative, the temperature of the steam being built up until it finally emer s through a screen 37 at the working end df the inner tube into the casing at the temperature desired to produce the best working results.

The heat is given up to the work and the temperature of the steam is reduced at this point to some extent. It then flows backwardly through the porous mass 12 in the casing. This mass 12 is an insulating mass which prevents the short-circuiting of the inner tube and coil to the casing and it is heated by the steam to a relatively high temperature and hence operates very efiectively in preventing loss of heat from the tube and coil in which it is generated electrically.

Steam in passing back to the casing is at a suificiently high temperature to give up heat to the incoming steam. This heat transfer takes place to a greater extent as the steam travels away from the working member, and it will be clearly understood that a large porportion of the heat remaining in the steam as it passes through the casing is taken up by the incoming steam as it enters the inner tube. By this means the steam which finally escapes from the casing at 22 through a screen 38 is only slightly higher in temperature than the steam which is supplied to the inner tube.

It is therefore evident that the loss of hea when the structure is in use, is very slight. lVhen the device is not in use the electric energy may be shut oil and the steam allowed to percolate through the tool. The steam constitutes a relatively low cost source of heat and without the use of electric current will maintain the tool at a temperature materially above that of the atmosphere. In many classes of workthe standbylosses under ordinary conditions are relatively great when electricity is utilized as the sole source of heat.

A particularly important feature of my inventidn however, is the rapid and effective concentration of heat at the working member even though the member may be small in size. It is for this reason that the structure of my invention overcomes the usual difficulties of providing electric heaters for small tools and like purposes, and avoids the expense usually involved inresorting to translating devices as already explained.

Attention is directed to the fact that I do not depend upon conduction through metal to carry heat to the working member and the working member may of course be formed in various ways. It may constitute a soldering point 21 as shown in Figure 5, or a cautery 23 as shown in Figure 6. The heat is supplied as fast as required by'the flow of the steam or other fluid which constitutes a,heat carrier. 7

In addition to the aforesaid advantages the exchange of heat between the outgoing vapor in the outer casing and the incoming vapor is highly important and advantageous.

Still further advantages which will be readily understood by those skilled in this art are-secured by my present invention on account of the simplicity of the structure itself and on account of the fact, that the heat is effectively transferred from the heat generating elements to the casing or armor without the necessity of subjecting any of the parts to compression.

While my invention is well adapted to concentrate heat at a very small area such as at the end of the unit, it is by no means limited in this regard, and it will be understood that heat is transferred to the casing or armor 10 from which heat may be taken for any useful purpose. If the heat is only to be utilized near the end of the structure the remainder may of course be covered by a suitable heat insulation designated 24 in Figure 6.

The forming of the unit into a coil is illustrated in Figure 9, the coil is designated 25 and the point of the instrument which may be adapted for pyrographic work, is designated 26. The coil is provided with a tubular casing 27, the fluid supply pipe being designated 28, and the electrical conducting leads 29.

The structure of the unit or element may be varied within the spirit and scope of my invention. For example, attention may be directed to Figures 7 and 8 in which the electrical heat generating unit comprises an inner tubular member which is bent into U- shape and is perforated at or near the bend in the U as indicated at 31. The two branches of the tube are electrically separated by a porous insulating mass 32 which corresponds to the mass 12, andthe ends of the tube are connected electrically to the circuit conductors 17 and 19 and mechanically to the steam inlet pipe 33.

The tube is surrounded by a casing or armor 34 corresponding to the armor 10. The end of the unit is shown enlarged at 35 to constitute a stove or aheater for any suitable purpose. The tube 30 may be flattened as shown in Figure 8 so that the casing may be circular in form without material waste space within. In this case the returned vapor escapes at 22 through the screen 39.

Still another modification of my invention is shown in Figures 13 and 14 which comprises an outer casing and a pair of inner tubes 41 and 42, which are spaced apart and from the casing by amass 43 of insulation. Each of the tubes is formed to correspond to the inner tube 11. The tube 41 for example,

is closed at one end except for perforations 44 and has a heating coil 45 within it and connected to it near its perforated end. The coil is electrically separated from it except at the point of connection by an insulating mass 46 correspondingto the mass 14.

Within the same outer casing 40 there are two tubes and two coils" and'they' may be connected electrically in series as clearly' shown in Figure 13 or in any other suitable relation. The structure shown in Figures- 13 and 14 may be utilized in various ways. It may for example, be applied to an electric laundry iron'as shown in Figures 10, 11 and a laundry iron and it is particularly difficult to accomplish this'result because of the constant demand for heatat this point.

By utilizing a pair of heater structures of the character just described and bringing their hot ends together at the point of the iron, a high temperature/is produced and maintained at the point. As shown in Figures 10, 11 and 12, there are two lengths of tubular casings 4O curved to correspond to the curvature of the body of the iron into which the units are cast.

In casting'the body 47 of the iron the tubes 40 are arranged with their open ends extending into a pocket or chamber 48 near the pointof the iron. Atthe heel of the iron the tubes 40 are bent upwardly and. come out of the casting at the top. The inner tubes 41 and 42 are joined bya connecting tube 50 to which a fluid supply pipe 51 is connected.

The tubular casings 40 open into a chamher or jacket 52 which is formed by a'cov'er plate 53 of the iron. This chamber is sealed except near the point of the iron where it opens through a narrow channel 54 and discharges downwardly onto the work.

The pipe 51 may have'the form of a fiexi ble tube and steam is supplied therethrou-ghto the inner tubes 41 and 42. It flows forwardly through these tubes and; is he'ated't high temperature by' the electric heating elements comprising the tubes themselves and the coils 45. It is finally discharged into the chamber 48 and then flows back through the tubular casings 40, giving up its heat to the iron and also preheating the incoming vapor. It is finally discharged into the chamber 52 and through the passage 54 onto the goods. I

If the ironing operation is-ju-st' begun and the gddds are cold. the vapor will be conden sed and the goods will be moistened, thus avoiding the necessity of moistening in advance. When the goods are heated and the ironing operation is practically complete the hot steam which is still at asuliiciently-high temperature to be dry, is discharged without having any material efi'e'ct on the goods. I As further indicating the scope of my inlike.

for example, in small furnace work, or the like, I prefer to employ for at least a portion of the structure, elements which are better adapted than ordinary metals to withstand the high temperature conditions imposed.

As shown in the drawings 60 designates the metallic portion of the outer casing and-61 the high temperature portion which may be formed of a. quartz tube, a fulgarite or the This tube is joined in some suitable manner to one end of the metal tube 60, the sleeve 62 being indicated as a convenient means for this purpose. Within the casing is a relatively small tube 63 which corresponds to the tube 11 of Figure 2 and which may be formed into a coil as shown in order to increase its length relative to the metal casing 60.

Joined to the inner tube 63 is a tubular member 64 which may be formed of molybdenum, tungsten or like material. In some instances this high temperature section of the inner tube may be formed of some suitable fulgarite which will act as a conductor when its temperature is sufliciently high. The device further comprises an electric heater. 65 which may correspond to the coil lation.

13 of Figure 2 and one terminal 66 of which extends throughthe tube 63 and the other terminal may conveniently be wrapped around the molybdenum or tungsten element 64: and then brought back through the casing section to the terminal end 67.

In the casing member 60 I have shown vapor taps 68 and 69 to which suitable tubes or pipes 70 and 71 may be connected.

The electric heater is spaced from the inner tube and the inner tube is held in position and spaced from the casing by a porous mass 7 4 of suitable insulating material which may consist ofv carborundum particles in granular form as already described in connection with the arrangement shown in Figures 1 and 2.

The concentration of heat is not only effected by the flow of the vapor which carries the heat towardcthe hot end of the device. but may also be considerably assisted by the positive temperature coefficient of the electric'heater under the influence of the temperature produced by the vapor accumu- The concentration .of heat may be still furtheraugmented by making the insulating mass through which the vapor must percolate, finer; grained near or at the high temperature portions of the device. For example, the casing section 61 and the inner tube section 64 which make up the hot end of the device illustrated, may be filled with grains or particles designated 75 which are finer than those in the sections 60 and 63 where the temperatures are comparativel low and where the design makes it practlcable to largely increase the surface of the inflowing tube compared to that of the outgoing vapor. 1

For example, the inner tubular member 63 may be coiled within the casing as shown, in order to increase the length of the path and the resistance to the inward flow relative to the outward floiv of vapor through the casing section 60. Under these conditions it will be desirableto permit the vapor to fiow' more rapidly through the outer casing and hence larger insulating particles maybe advantageously used as above indicated.

The tubes 68 and 69 may be used as independent sources of hot vapor, their temperature depending on the position of the taps, or they may be employed as an inlet and the other as an outlet for supplying heat from superheated steam or some other available source which is at an intermediate temperature between the incoming vapor supplied to the inner tube 63 and the working temperature of the device.

It is evident that while I have only illustrated a few Ways in which the heater element of my invention may be employed, it is capable of very wide application, and I intend that only such limitations be imposed as are indicated in the appended claims.

What I claim is: I

1. A heater comprising a heat intensifying member having a fluid passage. means for electrically generating heat therein. and an outer casing adapted to provide a heat exchange chamber.

2. A heater comprising a heat intensifying member having a fluid passage and means for electrically generating heat therein, and an outer casing adapted to provide a heat exchange chamber communicating with the fluid passage and constituting an outlet therefor.

3. A heater comprising a heat intensifying member having a relatively long fluid passage and means for electrically generatlng heat therein, and an outer casing coextensive with the intensifying member and spaced therefrom to provide a heat exchange chamber. I

4. A heater comprising aheat intensifying member having a relatively long fluid passage and means for electrically generating heat therein, and an outer casing coextensir-e with the intensifying member and spaced therefrom to provide a heat exchange chamher, said casing being connected to the fluid passage at one end-whereby fluid may pass through the passage and return through the exchange chamber. 1

5. A heater comprising a heat intensifying member having a fluid passage, heat absorbent material therein adapted to permit the gradual flow of fluid therethrough, means for electrically generating heat in the passage, and. an outer casing adapted to provide a heat exchange chamber.

6. A heater comprisin a heat intensifying member having a fluid passage, heat absorbent material therein adapted to permit the gradual flow of fluid therethrough, means for electrically generating heat in the passage, an outer casing, interposed insulatin material adapted to permit the flow of flui therethrough, whereby the outer casing constitutes an exchange chamber.

7 A heater comprising an elongated heat intensifying member having a fluid passage, means for electrically generating heat therein, an outer casing coextensive with the heat intensifying member, interposed porous insulation for electrically separating the easing from the heat intensifying member. said passage being in communication 'with the casing, so that the CflSlIlg'CDIlStltlltQS a heat exchange chamber.

8. A heater comprising an elongated heat intensifyin member having a fluid passage, means for e ectrically generating heat therein, an outer casing coextensive with the heat intensifying member, interposed porous insulation for electrically separating the casing from the heat intensifying member, said passage being in communication with the casing at one end whereby fluid may pass through the passage in one direction and back through the casing in the opposite direction.

9. A heater comprising an elongated heat intensifying member havmg a fluid passage,

a porous heat absorbent material within the passage, means for electrically generating heat in the passage, an outer casing coextensive with the heat intensifying member, and interposedporous insulation for electrically separating the casing from the heat intensifying member, said passage being in communication with the casing so that the cas:

ing constitutes a heat exchange chamber.

10. A heater comprising an elongated heat intensifying member having a fluid passage, a porous heat absorbent material within the passage, means 'for electrically generating eat in the passage, an outer casing coextensive with the heat intensifying member, interposed porous .insulation for electrically separating the casing from the heat intensifying member, said passage being in communication with the casing at one end, whereby fluid may pass through the passage in one direction and back through the casing in the opposite direction.

11. A heater comprising an electric heating element, a sheath or armor in which the heater is disposed, porous insulation between the heater and the sheath, and means with which the heating element is associated for conducting hot vapor through the device to rapidly increase the temperature and then through the insulation to transfer the heat to the sheath and preventrloss of heat from the. element.

12. A heater comprising an inner conductor constituting an electric heating element and a fluid inlet pipe, means in the pipe to retard the flow of vapor therethrough, an outer sheath spaced from the inner conductor and connected thereto at one end, and insulating means between the inner conductor and the sheath adapted to permit the flow of vapor therethrough.

13. A heater comprising an electric heating element forming an inner passage through which hot vapor may be supplied, porous insulation surrounding the heating element, and a. sheath forming a vapor chamber and spaced from the heating elemeht by the orous insulation.

14. A heating element adapted to dissipate heat comprising an outer meta sheath or armor, an electric heating element within, and interposed porous insulation, said heater constituting-means' for conducting heated vapor into the element, and said sheath constituting means for leading vapor away, whereby the heat is transferred from the heating element to the, sheath by the vapor and whereby .the vapor prevents loss of heat from the element. 1

15. A heater comprising an electric heating element, a vapor inlet passage receiving heat from the heating element, a heat conducting sheath comprising an outlet passage and porous insulation in the outlet passage to support the electric heating element without prevening the flow of vapor through the outlet passage.- I

16. A heater comprising an elongated heated tubular resistance element, a sheath of conducting material surrounding the 613-.- ment and interposed porous insulation, said tubular resistance" element being in communication with the sheath at one end whereby vapbr may be supplied to the heater element, then flow slowly through the insulation to'transfer heat to the sheath.

17. A heater comprising a heat intensifying member having a fluid passage, means for generating heat in one portion of said passage, and an outer casing adapted to having a relatively low temperature heat 130 exchange section and a high temperature fluid passage heat intensifying section, means for generating heat in the heat intensifying section, and an outer casing arranged to provide a return passage for the fluid adjacent to the heat exchange section of the inner member.

20. A heater comprising an inner tubular member having a heat exchange coil, and a high temperature section, means for generating heat in the high temperature section, a casing having a high temperature working member surrounding the heat intensifying member Within, and a heat exchange section surrounding the coil of the inner member, said casing providing a return connection for the fluid.

21. A heater comprising a tortuous fluid passage, a heat intensifying member connected thereto, an electric heater for gencrating heat in the heat intensifying member, a casing surrounding the inner member and interposed porous insulation for spacing the casing therefrom.

22. i heater comprising a tortuous fluid passage, a heat intensifying member connected thereto, an electric heater for generating heat in the heat intensifying member, a casing surrounding the inner member and comprising a high temperature working section of refractory material, and a relatively low temperature heat exchange section of metal, and means for separating the casing from the inner member without preventing the flow of heat carrying fluid therethrough.

23. A heater comprising a heat intensifying member having a fluid passage, means for electrically generating heat therein, an outer casing adapted to provide a heat exchange chamber, and spaced taps in said heat exchange member.

24. A heater comprising a heat intensifying member having a fluid passage,heat absorbent material therein adapted to permit the gradual flow of fluid therethrough, means for electrically generating heat in the passage, an outer casing adapted to provide a heat exchange chamber and a porous mass offering a graded resistance to the return flow of vapor through the casing.

25. A heater comprising a heat intensifying member having a fluid passage, heat absorbent material therein adapted to permit the gradual flow of fluid therethrough, means for electrically generating heat in the passage, an outer casing, interposed insulating material adapted to permit the flow of fluid therethrough, whereby the outer casing constitutes an exchange chamber, said interposed insulating material being arranged to concentrate the heat at a predetermined portion of the casing.

26. A heater comprising a heat intensifying member having a fluid passage, heat absorbent material therein adapted to permit the gradual flow of fluid therethrpugh,

means for electrically generating heat in the passage, an outer casing, interposed insulating material adapted to permit the flow of fluid therethrough, whereby the outer casing'constitutes an exchange chamber, said interposed insulating material being composed of a fine grain section to concentrate the heat and a coarser grain section to permit the flow of fluid therethrough.

27. A heater comprisin a heat intensifying member having a fluid passage, an electric heater within the passage having a positive temperature coeflicient, and an outer casing adapted to provide a heat exchange chamber.

28. A heater comprising a heat intensifying member having a relatively long fluid passage, an electric heater within the passage having a positive temperature coeflicient and an outer casing coextensive with the intensifying member and spaced therefrom to provide a heat exchange chamber, said casing being connected to the fluid passage at one end where-by fluid may pass through the passage and return through the exchange chamber.

29. A heater comprising a tubularbody having a tool or working member constituting a closure at one end of the tube, an inner tubular member adapted to discharge heating fluid into the outer member near the tool, and means for generating heat in the inner member.

30. A heater comprising an outer member having a discharge opening at one end and a working member or tool at the opposite end, a heating fluid conductor extending. close to the working member or tool within said tubular member, and means for generating heat in the inner member.

31. A heater comprising an outer member having a discharge opening at one end and a working member or tool at the opposite end, a heating fluid conductor extending close to the working member or tool within said tubular member, and means for electrically generating heat in the inner member so as to cumulatively increase the'temperature of the heating fluid.

32. A heater comprising an outer membe hvaing a discharge opening at one end and a working member or tool at the opposite end, a heating fluid conductor extending close to the working member or toolwithin said tubular member, an insulating mass adapted to hold the inner and outer members in spacedrelation, said mass being porous to constitute means for retarding the flow of the heating fluid. I

33. A heating tool comprising a tubular body having a working member at one end, an inner heating fluid conducting tube extending into thetubular body and adapted to discharge close to the working member, in-

terpose granular insulation for retarding I the not be heating fluid and spacing the outer from the innermember. anelectric conductor -'connected' to the tubular member at its inner end and imbedded in the insula'ting material, said electric conductor and body having a working member atone end, an nner heating fluid conducting tube extendin into the tubular body and adapted todisc ar e close 'to the working member,

fine-- granu a'r' insulation between the discharge end of the inner tube and the workingmember' and relatively coarse granular insulating material between the outer and innertubular members, and means co-operatin with the inner tube for establishing an e ectric heat generating circuit.

35."A heater comprising a tubular body having a working member at one end and a discharge outlet at the opposite end, a tubular inner member of U-shaped formation, perforated at the bend of the U and extending into the outer tubular body close to the working member thereof, means for supplying heating fluid to both branches of the U-shaped inner member, and means for establishing a heat generating circuit through said inner member.

36. A heater comprising a tubular body having a working member at one end and a discharge outlet at the opposite end, a tubular inner member of U-shaped formation, erforated at the bend of the U and exten ing into the outer tubular body close to the working member thereof, means for supplying heating fluid to both branches of the U-shaped inner member, means for estabsaid inner member, and porous heat insulalishing aheat generating circuit through tion interposed between the inner and outer members and constituting means for retarding the flow of the heating fluid.

37. A heater comprising a tubular body of circular section having a working member at one end and a dischage outlet at the opposite end, a tubular inner member of U- s'haped formation flattened in section, perforated at the bend of the U and extending into the outer tubular body close to the working member thereof, means for supplying heating fluid to 'both branches of the U- shaped inner member, means for establishing a heat generating circuit through said inner member, and porous heat insulation interposed between the inner and outer members and constituting means for retarding the flow of the heating fluid.

'38. Ina heating tool, a heat generating element, means for conducting a heat transferring medium from said element to a desired portion of said tool, and means for discharging said medium upon the work.

39. In a heating tool, a heat generating element, means for conducting a vapor from said element to a desired portion of said tool whereb heat is transferred thereto, and means or discharging the vapor upon the'work.

40. A heating tool comprising means for injecting a vapor into sald tool, a heating element for raising the temperature of the vapor, a vapor conductor adapted to conduct the heated vapor to a desired portion of the tool, and means for discharging the vapor upon the work.

41. A heater comprising a casing, a heat generating element, means for circulating a heat transferring medium within said casing, and a porous material for maintaining said element positioned within said casing for retarding the circulation of the medium.

42. A heater comprising a casing, a heat generating element, means for circulating a heat transferring medium within said casing, and a porous material for maintaining said element positioned within said casing for concentrating the heat at a desired portion of said casing.

43. A heater comprising a casing, a heat generating element, means for circulating a heat transferring medium withln said casing, and a porous material for maintain-.

a fluid inlet conduit, and meansfor returning the heated fluid along the outside of the conductor.

47 Intercommunicating inlet and outlet heat exchange conduits and an electrical heater integrally combined with' the inlet conduit.

48. Intercommunicating inlet and outlet heat exchange conduits, a heater in the inlet conduit, and' means in at least one of said conduits for breaking .up the fluid and retarding the flow thereof.

49. Interoommunicating inlet and outlet heat exchange conduiw, a heater in the in let conduit, and means in said conduits for breaking up the fluid and retarding the flow thereof.

50. Inlet and outlet heat exchange conduits, a chamber interconnecting said conduits, and means associated with the inlet conduit for cumulatively heating vapor therein as it approaches said chamber.

51. A fluid inlet conduit, a chamber at. the discharge end thereof, means for progressively increasing the heat. of fluid in said conduit, and means for returning the heated fluid from the chamber along the outside of the conduit.

52. A fluid inlet conduit, a chamber at the discharge end thereof, means for progressively increasing the heat of fluid in said conduit, and means for returning the heated fluid from the chamber around the outside of the conduit.

53. A member constructed to form a fluid conduit, means for progressively heating a fluid as it passes therethrough, a casing forming a chamber adapted to receive the heated fluid at the discharge end of the conduit, and providing means for returning the fluid from said chamber along the outside of the conduit.

54. A member constructed to form a fluid conduit, means for progressively heating a fluid as it passes therethrough, a casing forming a chamber adapted to receive the heated fluid at the discharge of the conduit to form' 'a heat exchange jacket surrounding the conduit.

55. A fluid inlet conduit, a chamber at the discharge end thereof, means for progressively increasing the heat of fluid in said conduit, means in said conduit for breaking up the fluid and retarding the flow thereof, and means for returning the heated. fluid from the chamber around the outside of the conduit.

56. A member constructed to form a fluid conduit, means for progressively heating a fluid as it passes, therethrough, a casing forming a chamber adapted to receive the heated fluid at the discharge of the conduit to form a heat exchange jacket surrounding the conduit, and means in said conduit and jacket for breaking up the fluid and retarding the flow thereof.

In Witness whereof I have hereunto set my hand this 18 day of May, 1917 WILLIAM S. HADAWAY, J R.

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