US2101922A - Spraying apparatus - Google Patents

Description

Dec. 14, 1937. L. sToEsLlNG SPRAYING APPARATUS Filed Feb. 19, 1935 2 Sheets-Sheet l I/v VEN TOR L U0 w/G STOESL//VG A rroR/vy.

Dec. 14, 1937. g STOESUNG 2,101,922

SPRAYING APPARgTU Filed Feb. 19, 1935 2 sheets-sheet 2 Y [NVE/v70@ LuDw/G SToEL//VG A TToR/VEY.

ZNE RECEIVING JUD/V/DED MATER/AL Patented Dec. 14,- 1937 UNITED STATES PATENT OFFICE sPnAnNG APPARATUS Ludwig Stoesling, Monrovia, Calif. Application February 19, 19a-esami No. 7,237

21 Claims.

- My invention relates to devices and methods for applying coatingsor deposits on a surface, and more particularly to a novel method and apparatus for spraying various materials onto such a surface for protecting or other purposes vsuch as for water-proofing, acid-proong, alkali-proofing, etc.v

For purpose of definiteness and illustration the invention will be particularly described in co'njunction with a novel water-proofing process which also produces an acid-proof and alkaliproof, though it should be understood that various materials can be applied and that various functions can be-y performed by the applied coating materials. v

Various processes of. applying water-proong coatings are known to the art, but all are subject to many objections as to mode of application, effectiveness, or cost. Thus, it has been proposed to apply parailin coatings to porous surfaces such as concrete, brick, rock, etc. by application of paraiiin in melted condition by means of a brush. This process is not only objectionable in its mode of application but tests have demonstrated that the paraiiin does not penetrate to the desired depth to be completely effective in the -absence 'of auxiliary steps performed only at prohibitive cost. So also, 'one of the-most widely used processes applies paraiiln while dissolved in a solvent, evaporation of this solvent leaving a deposit of paraffin. This process is unsatisfactory `for many existing conditions in that the resultant deposit is of a spongelike character and will not completely prevent the passage therethrough of -water or other liquids.

Generally speaking, the invention has two aspects, especially with regard to the problem of spraying materials such as parafiln. These two factors or aspects involved can best be explained and illustrated in conjunction with a parainspraying system, and for this reason the invention will be particularly described with reference thereto, though it will be clear that somewhat similar factors are present in the spraying of Avarious materials. In the ilrst place'. spraying any material such as parailin has beenyheretoiore impractical due to the fact that the atomized parafn solidies to form a snow as soon as it is discharged rom the spraying device, thus preventing any material amount of penetration. In the present invention the atomized stream of parafn or other material is protected from contact with the atmosphere as it moves toward the surface on which the deposit is to be formed. In the second place, the problem as to how to secure greater penetration of the coating material has been a serious and unsolved one. In the present invention greater penetration of the material is obtained'by the proper application of heat, the spraying devices herein illustrated eiecting a novel pre-heating and post-heating of a particular zone in the surface, as will be hereinafter described.

It is an object of the present invention to provide a-novel method of spraying a material onto a suriaceand which has superior penetrating and pressure-withstanding powers, and which produces a coating which has superior protecting properties.

It is a further object of the invention to spray a liquid or powdered material onto a surface in such a manner that the material is protected from contact with the atmosphere during its travel from the spraying device to the surface.

Another object of the invention is to provide fa novel spraying method in which the spray of subdivided material is surrounded by a moving 'stream of gas as it is projected toward the suriace to be coated.

It is another object of the present invention to provide a novel method of spraying which is very satisfactory for use with materials which solidify upon cooling, such as parann, the material being atomized while in melted state and being prevented from cooling while in this atomized state by heat applied to the atomized material before it reaches the surface,l or by surrounding the atomized material with an envelope of gas preventing direct heat transfer between the atomized material and the atmosphere.

A further object of the present invention is to provide a novel method of pre-heating and postheating a zone of the surface to increase the penetration or otherwise increase the effectiveness or integrity oi the coating.

It is another object of the' present invention to provide a novel low-pressure method of spraying applicable to various uses and very satisfactory for spraying various materials.

The' apparatus for supplying such a coating, constructed as shown or suggested herein, is also believed to be novel, and it is an object of the present invention to provide a novel concentricstream spraying device for sprayingY various materials in subdivided form. y

It is a further object of the present invention to provide a novel spraying device having a novel l relationship between a heating means and the other elements of the device and also a device in which the heating means is of novel construction.

It is a-further object of the linvention to provide a heat-responsive structurein such a spraying device for indicating or controlling the temperature developed.

A further object of the invention lies in the provision of a spraying device with a main passage in which is positioned a tube, a stream oi'v gas being moved ,through this tube and another stream of gas being moved through anv annular space betweenthe tube and the walls of the main Passage- It is a further object of the invention to provide an outer Venturi tube in conjunction with a tube therein, or sometimes in conjunction with a structure in which this tube is in` the form of an inner Venturi tube, this 'double-venturiy having -beenfound to be very effective in producing the concentric streams.

Another object of the invention lies in thel provision of a novel low-pressure spraying device. and is very satisfactory in spraying materials which solidify when exposed to the atmosphere. K

Further objects and advantages of the invention will be made'evident to those skilled in the art from the following description of several embodiments of the invention. i

Referring to the drawings:

Fig. l is a vertical sectional view of one em-' ffalls within the objects enumerated above: The

spraying device therein shown is of the manual'- ly-supported or portable type and includes a body structure Il. 'I'his body structure may be formed of a singlemember, but is preferably formed of a cylindrical shell il with a plate i2' 'extending across the forward end thereof and detachably connected thereto as by screws Il,

this body structure forming a chamber i4 inside the shell il.

Extending rearwardly in the chamber il are inner and outer tubular members il and i1 suitably secured at their forward ends lto the body structure Il. In the embodiment shown. the inner tubular member i. is pressed into an opening of the plate I2, while the outer tubular member I1 is pressed into an opening of the shell. Il.

These tubular members 'are spaced from Veach other to define an' annular space il into which a heating unit 2l extends.

This heating unit 2l may take any one of a various number of forms. In the embodiment illustrated it includes a rear head`2| and a for` ward-extending sleeve 22 formed integrally or separately of a suitable heat-resistant material such as baked fireclay, the material which I prefer using being fA1undum". The rear head 2| may be vused to whollyor partially Aclose the rear end of the chamber Il, beingfshown as belns ing connected to the shell Il by screws/22 which extend through a protecting ring 2l and through a picking of asbestos or lother material 2B sep arating this ring from the rear head 2l.

'I'he sleeve 22 divides the annular space' i! between the inner and outer tubular members It and I1 into inner and intermediate annular passages 21 and 28; 'I'he forward end of the' sleeve 22 terminates short of the plate i2 so as to .throw the forward ends of these annular passagesl into communication, thereby providing a tortuous passage through which 'a stream of gas may be moved, as will be hereinafter described. y

A -suitable heating means 2! is supported by the sleeve 22 and is shown as comprising a coil of resistance wire wound helically around` the sleeve 22. Ihe several turns of this helicallydisposed winding are permanently spaced from each other by winding the coil in a helical groove 3U which is preferably of greater radius of curvature than \the ycoil itself. -With such a construction it is possible to obtain a maximum heating of the gas moving through the intermediate passage 28 for the gas comes into contact with substantially all portions of the resistance wire, the only portion not contacted by the gas being the smallyportion thereof engaging the bottom of the helical groove 30. This gas is also heated vby contact with the heated sleeve-'22 as it flows therealong. Y

'I'he requisite current may be supplied to the heating unit 20 through conductors 3i and 22 connected to suitable terminals of a socket retained in the rear head 2|. A plug 28 provides correspondingly placed terminals supplied with current through two conductors oi a cable 31. these .conductors being indicated by' the numerals 3l and '39.

A stream of gas is supplied tothe spraying device preferably through a handle Il which may be formed of a. length of pipe, the. cable 81 extending therealong and being held in place by a cord or other member wound therearound. In many instances this gas can be air supplied to the handle ll through a hose 42 detachably connected thereto, fa suitable pumping means 43 being utilized, this pumping means being illustrated as a conventional low-pressure blower. The air moving upward in the handle 4U isv discharged into an annularspace 45 between the shell il and the outer tubular member I1, flowing peripherally around this tubular member and toward th'e rear end thereof as indicated by the arrows I8. This stream of gas then moves lthrough the intermediate annular spaceA 28 as .indicated by the arrows I1, being therein heated by the coll of resistance wire and by contact with the heated sleeve 22. 'Ihis air continues its movement through the` tortuous passage by movlng through the inner annular space 21 as indicated by the arrows 48. being additionally heated therein by contact with the sleeve 22 and being then guided so as to move as a main stream through the inner tubular member it, as indicated by the arrows 49. If desired, this main stream may be given a rotary movement as it moves through the inner tubular menber I6 by riding the passage "defined thereby or by po' viding helically-disposed vane means '5| therein.

' However, it should be clear that it is not essential to the operativeness of the device that such a rotary movement be imparted to the main stream of gas, though this auxiliary factor is desirable incertain instances.

While separate sources maybe utilized for supplying the concentric streams of atomized material and gas moving toward the surface to be coated, I prefer to divide the main stream of gas moving through the passage 58 into inner and outer streams, the inner stream being utilized to carry the subdivided material to the surface. In the embodiment shown in Fig. 1 this is accomplished by the use of a head structure Ell shown as comprising a head 6I detachably connected to the plate I2 and carrying a nozzle 62 extending forwardfrom this head. The head structure 60 provides an opening 84 forming a part of the main passage and which, in the embodiment shownv in Fig. 1, is in the form of an outer Venturi providing a throat 85 which is somewhat smaller in diameter than the rearward and forward flared portions-66 and 81 thereof. A tube 88'iscentrally disposed in the opening 64, being preferably secured to the head 8| as by an arm 69.'. Ihis tube 68 is'of smaller diameter than the opening 64, the forward end vthereof bounding an inner orifice means 10, this sleeve cooperating with the opening 64 in defining an outer orifice means 1I of'annular shape.

Means is provided for `supplying to the innerA orifice means 10 the subdivided material. In the embodiment shown in Fig. l this is accomplished by forming the tube 68 as an inner venturi, the atomized material being discharged therefrom in or near the throat 85 of the outer venturi'. This inner venturi is shown as providing apas- 'sage including a throat 13 and forward and rear;

Ward diverging portions 14 and 15. The rear end thereof is relatively sharp so as to divide the main stream of gas into two streams, one flowing through the passage of the inner venturi, and the other flowing through the annular space between the tube 68 andthe walls of the opening il. i

The material to be atomized or subdivided isA moved into the tube 88 preferably at a position adjacent the throat 13. A suitable passage means is utilized in this regard, being shown as including a vertical passage 11 extending throughvthe arm S9 and communicating with a horizontal' passage 18, the flow of material through these passages being controlled by the setting of a valve 19 shown in open position. A handle 8D serves to permit manual movement of this valve, the

valve being closed when this handle is in its dotted-line position. n

While any suitable conduit means may be utilized to supply the material to the passages 18 and `11, the preferred embodiment of the invention includes a receptacle 8| vfor this material and, positioned in heat-transferring relation with the same heating unit 20 as is utilized for heating the gas. As best shown in Fig. 2 this receptacle is secured to Afianges-82 extending sidewise from the shell I I and cooperates with the upper periphery `of this shell in defining a chamber 83, the lower portions of which are below the uppermost part of this shell, extending downward therearound. The material therein receives heat through the shell II. Thus, in spraying paraffin the paraffin can be introduced into the chamber 83 in solid state, being therein melted.

The material flows from the lowermost portions of the chamber 83 through` one.or more passages 84 extending through the shell II and the plate I2 and opening 'on an annular chamber or groove 85 formed in the forward face of the plate I2, this groove bein'g in communication at its upperV end with the horizontal passage 18. The material thus flows by gravity from 'the receptacle 80 to the throat of the inner venturi.

, In addition, Athe 'reduced-pressure in the throat of thel inner venturi (due to rthe increased vestate untill they reach the surface 88.

locity of the gas flowing therethrough) acts to forcibly withdraw the material from 'the receptacle 8l). In this connection it is possible with the lstructure shown to completely drain the chamber 83, a very desirable factor.

If desired, a nipple 81 may be positioned in the passage ,11 to extend a distance into the throat of the inner venturi, the lower end being angled as shown. However, the use of such a nipple is usually not necessary, the' device being entirely satisfactory if the material flows directly from lthe passage 11 into the throat 13. Regardless of whether or not the nipple 81 is utilized, it will be clear that the material moving through the passage 11 is picked up by the stream of gas moving through the inner venturi and is subdivided or atomized, the atomized material being delivered by the forward-diverging passage 14 to the inner orifice means 10. In the embodiment illustrated this atomized material is discharged toward a I changes in the material being sprayed or to hold the spray more intact.

If paraiiin is being sprayed,\it is essential that the liquid paraffin particles in this spray be maintained in liquid particles are allowed to cool, either by contact with a cool atmosphere or by excessive expansion of the gases discharged from the inner orifice means 10, solidiiication thereof will take place and it will be impossible to spray the paraffin in liquid state onto the surface 88. Such solidiflcation canbe avoided by applying heat to the atomized material after it is discharged from the spraying device, or by separating the atomized Amaterial from the atmosphere by a heatinsu lating stream of gas which is usually itself heated, or by both of these expedients. In the embodiment shown in Fig. l, both expedients are uti lized, though it will be clear that these expedients can be separately utilized. In this connection it will be noted that the annular orifice means 1I discharges an annular stream of gas which is con- If these centric with the stream of atomized material,

the outer boundaries of this stream of gas `being indicated by the dotted lines of Fig. l. This stream of gas tends to heat-insulate the stream of atomized material from the surrounding atmosphere. Further, in the embodiment' shown in Fig. 1 this annular stream of gas is heated, thus further tending to prevent cooling of the atomized' material. It is sometimes preferable to maintain this stream'of gas at a temperature somewhat above the temperature of 'theatomized material, thus actually heating the atomized ma'- terial further during *its passage from the spraying device to the surface 88. In' this connection it will be clear that while the temperature of the f.

gas entering the inner venturi is the same as the gas moving through the annular space between the tube |58- and thewallsof the opening 64, vthe atomized material moving from the inner orifice means 10 is somewhat cooler due to the addition of the somewhat cooler material to be atomized and due to any expansion which takes placein the forward-diverging passage 14. Thus, the temperature of the annular stream of gas discharged from the outer orifice means 1I is considerably higher, and by proper design the ternperature of the surrounding conical stream of air the forwardfdiverging passage 'M is an important i one.l I have found that in spraying such materials it is impossible to secure goodi'results it lv thepressure of the pump means 43 is too high. Heretofore all .spraying processes with which I am familiar have utilized pressures of from to 100 lbs./sq. in. or more. While such pressures can be sometimes utilized in my spraying device y 1,5 in spraying certain materials, these pressures are entirely ineectual to produce best results when spraying other materials such as paramn, or

other materials which solidify uponpexposure to .they atmosphere. With such materials I have 20 found it desirable to utilize much`lower pressures, using, in fact, as low a pressure as pos/sible and still secure the desired atomiz'ing'action. With such materials best results are secured if the pressure in the main passage -'doe`s not exceed a few pounds per square inch, with one or two exceptions pressures of not to exceed three pounds per square inch have been entirely satisfactory. In spraying paramnand certain other `materials I prefer to utilize as low a pressure as possible, the pressure being'only sufficient to insure that the atomized material will move to the surface to be y coated. Entirely satisfactory results have been obtained by utilizing pressures of twelve inches of water or less. One factor in this connection is', of

course, the direction of movement of the sprayed material. If thespray isdirected'vertically upward, it is usually necessary to use pressures oi' l between eight and twelve inches o f water. When the spray is directed -horizontally or vertically 40 downward, pressures as low as four l water are very satisfactory. 1

There are several reasons for my utilization of low pressures in the'p'referred embodiments of my invention. In the, first place,- it is very desirable that the atomized particles be not impinged upon the surface 98 at such high velocity that they will rebound therefrom. This factor is especially importantif the atomized lstream is in 'the form of a cone, for if the velocity of the atom- 5'@ ized particles is too nigh these particles wiu rebound from the surface B8 outward towardthe I surrounding stream of gas and sometimes therethrough so as to contaminate the surrounding at mosphere or be prematurely deposited in solid gform on surfaces which are to be later coated.

In the second place, it is important to maintain the atomized parain particles in liquid state during passage from-the spraying device to 'the- .surface 88,.v In this connection it is importantto Icooling the atonized particles.

o0 prevent cooling of 'these' atomized'particles to any great degree. If high-pressure gas is utilized for` formation of the spray of atomized material, this gas excessively expands upon being discharged from the inner.A orice means, thus 'necessarily As an example of this, -I have found that `if the temperature of the atomized stream of paraflin is 600, F. at the forward end-of the nozzle l2, the temperature onehalf inch in front of this positionwill be 590 In'the spraying of parain or certain other may agendas I utilizing high pressures, the temperature of the atomized materiali as it leaves the' spraying device' m-ay b'e 300v F., vdropping, to .i 300 F. by the time that the atomized material reaches` the surface, a drop in temperature of 400 F. This excessive drop in temperatureis caused primarily by the greater expansion of `the gas in the atomizedv spray, but isinuenccd also by the higher velocity of the outerV stream of gaswhich tends to suck in a portion of the surrounding atmosphere, thereby cooling. this stream of gas. y

. In the third place, higher pressures result in higher velocities of the concentric streams. As to the surrounding stream `of gas,v such higher velocities are detrimental in that excessive turbulence is set up when this stream contacts the surface 8d. If lower velocities are utilized, this surrounding stream will fiare outward adjacent the surface 88, creeping therealong rather than rebounding therefrom or' creating excessive turbulence. 'This creeping action of the outer stream of gas is indicated'by the dotted lines 90 of Fig. l. Such a slower-moving stream'of surrounding gas also oiers greater resistance to spreading of the atomized stream when it contacts the surface 88. In the fourth place, it is desirable that this surrounding stream of gas transmit to the surface 8S as many of the heat units per unitof'time as y to use a relatively large quantity of heated gas mitting to the surface 88\the desired quantity of heat units. This expedient -alsoavoids the ex'- at higher velocity and thus incapable of trans-- cessive lover-heating `of the .gas resulting if a high velocity stream is Aused and if Vthetem'pera- 1 will often dtrimentally aifect the material to be sprayed, many of these materials losing their effectiveness if heated to too great a degree preparatory to application to a surface.

I 'usually find it desirable to provide on or adjacent the spraying device a heat-responsive means'e'ither in the form of 'a simple thermometer or in the form of a thermostatso connected as to lregulate the temperature'of Vthe gas. In the embodiment shownin Fig. 1, `I position such a Aheat-responsive means-in the path of flow of the l gas as it moves from, the intermediate passage 2i!v to the passage 50, being thus responsive to. the final temperature of the gasdelivered to this main passage. A sshown, this heat-responsive means includes a coil of bi-/metallic material 95 secured at on'e end throughv ai pin 96 to a dial 91 offa heat-indicating means 98.' This means is suitably encased in a shell 99 lclosed by a glass |00, the` 'shell 99 being retained in a cavity of the rear head .2i infthe -preferredembodiment of the invention. The other end of the bi^metallic strip :4 is securedv to a pin -lill which Vciairries a hand or. pointer |02 moving across suitable graduati'ons on the dial l1. Such a heat-responsive means will indicate to the operator the temperature'of the gas entering the main passagev 50.

` In addition, it issometimes desirable to utilize the heat-responsive means 88 as a thermostat to regulate the temperature of this stream of gas. In the embodiment shown this is accomplished by extending the hand |02 below the pin |0| to form a movable contact |04, which engages a stationary spring contact |05 when the temperature increases to or exceeds the desired degree, remaining out of Contact therewith at temperatures between atmospheric t-emperature and the desired temperature to be maintained. These contacts are respectively connected to conductors |06 and |01 extending to corresponding terminals of the socket 35 and forming a part of a control circuit,

.. the plug 36 containing correspondingly positioned Y from the conductor terminals connected to conductors |08 and |09 of the cable 31, the latter conductors terminating in an auxiliary plug ||0. A corresponding auxiliary socket lli indicated by dozted lines continues the control circuit to include the secondary winding l|2 of a step-down transformer H3, the primary winding of this transformer being connected across conductors ||4 and ||5 connected to a conventional plug H6. Also included in the control circuit in series with the secondary |2 is a winding of a relay ||1, this winding being indicated by thenumeral H8.

The conductors 39 and 38 carrying the main current to the heating unit 20 terminate in a main plug |20 adapted to fit in a main socket |2| from which extend conductors |22 and |23 corresponding to-the conductors 39 and 38. The conductor |22 is connected to the conductor ||4. The conductor |23 is connected to a contact |25 of the relay ||1 through an impedance shown as comprising a resistor |21, and is also directly connected to a contact |26 of this relay. A movable contact member |30 of the relay ||1 is normally retained in engagement with the contact |26 as by a spring |31. However, energization of the winding i8 of this relay moves this contact member |30 into engagement with the contact |25. A conductor |33 connects the, contact member |30 to the conductor I |5.

Assuming that the temperature is below the desired degree, the winding ||8 will not be energzed, and the contact member |30 will engage the contact |26. At this time current will now ||5 through the contact member |30, thence through the contact |25, the conductors |23, 38, and 3| to the heating unit 20. returning through the conductors 32, 39, and |22 to the conductor I4, thus energizing the heating unit to a maximum degree.

As soon as the temperature reaches or exceeds the desired value, the contacts |04 and |05 close,

thus completing the control circuit. At this time current ilows through this control circuit from the lower terminal of the secondary I2, and successively through the relay winding ||8, conductors |09 and |01, and thence through the contacts |05 and |04, yreturning to the secondary winding ||2 through conductors |06 and |08. This willenergize the winding ||8 to move the contact' member |30 into engagement with the contact |25. The effect of this change in position of the contact member |30 is to somewhat decrease the current flowing through the heating unit due to the fact that the resistance |21 is now in the main heating circuit. While it is sometimes. possible to completely cut off the vheating current when the temperature has` reached the desired degree, it is usually preferable to merely decrease this current to a value lnsumcient to maintain the desired temperature. Such a syslbe from alf to 1/2".

tem requires operation of the relay ||1 at less frequent intervals.

It will, of course, be understood that the thermostatic system disclosed isl only one of a number of control'systems which can be utilized for controlling the temperature of the gas moving through the main passage A50. Furthermore, if it is not desired to automaticallycontrol the tempcrature, the control circuit can be rendered inoperative by merely disconnecting the auxiliary plug ||0 and the auxiliary socket Various means may be' utilized for driving the 'pumping means 43. In the preferred vembodiment, I utilize an electric motor |40 in this capacity, connecting this motor across the conductors ||4 and H5.

' The superior penetrating yproperties of my method cannot be accounted for by any high ve- 4 locity of the atomized particles, for when low pressures are used the impact of these atomized particles is not sufficient to force these particles any material distance into the surface. However. my process has been definitely shown to produce a deeper-penetrating coating than existing processes. Thus, for instance, in spraying paraln on brick I have been able to secure penetrations of approximately two inches. In spraying ordinary concrete the penetration by use of my process will With blown concrete this penetration will be even greater. Thus with my process it is possible to obtain penetrations far greater than with other processes, these greater penetrations being more than double or triple the penetration possible, for instance, by the use of a paraffin-coating process in which a single application of the paraffin is applied with a brush orv tration available makes possible the formation of an impervious coating which will allow no water whatsoever to movetherethrough over an indelinitelength of time. In this connection I have found my method of -coating to be very effective in retaining moisture in a body of concrete by applying to the exposed surfaces of the concrete,

shortly after the forms have been removed, a

penetrating coating of paraiiin or similar material. After this is done I have found that the concrete contracts materially less than would be the case if the surfaces thereof were allowed lto remain in contact wlththe atmosphere. Furthermore, I have found that the contraction in such instance when utilizing my process is only one-fifth of the linear contraction which takes place if the lbest coating process now commercially available is utilized. I have furthermore found that by thus coating the surfaces of concrete after the forms have been removed the compression strength of the concrete is increased from 14% to 18%, and that the minute aircracks ordinarily formed if the concrete is allowed to vremain exposed to the atmosphere are entirely eliminated. These vnew results aredue to the 'lo Vconcrete.

met 'that my process is particularly effective' in preventing escape of any of the moisture which still remains rin the concrete, allowing all -of this moisture to be equally distributed throughout the crossesection of the concrete, andperess produces a penetrating coating capable of.

withstanding high pressures. Thus, if para is sprayed onto concrete by myfprocess, uti

l5 only small quantities of par'ifrom V3 to 1/2 oz. per square foot) the resulting coating `will withstand, pressures exerted on the face of the coating of 360 pounds perisquare inch or more.

Furthermore, ,if pressure is applied to the rear.-

2o ofthe concrete, thus tending to force the parain frizoni the coated surface, the coatingv applied by my process will withstand ures in excess ctl00 `pounds per square inch /without leakage or removal from the surface. i

One factor insecuring this incre penetration is the fact that the paraln particles are all maintained in liquidstate until they reach the "surface,v as distinct from other processes oi?v applying hot par in which a portion of the par may prematurelysolidify when applied with a brush or other applying means. Fundamentally, however, thedeeper penetration cfected by -my -process is caused by a novelpref heating and post-heating eiected by the enveloplng hot stream of gas and can best be underauftransverse..lines i435 to its, and the arrows adjacent this sinuous line, indicate the path of f movement of the central axis of thespray of. atomized material as the spraying deviceis ved to and fro in advancing relationship across the surface idd,- I have indicatediaf giveninstantaneous position of this axis by` the numeral 852. When in this given position the atomized stream will cover an area inside a circle H53, while the lstream' of heated gas will impinge agt the Surface lin a surrounding area dened between the circles i553 and |54. t Considering .the action which takes place in a zone B5B as the spraying device' is moved to the right along the dotted line ille, vit will be clearvv thatthls zone will be first pre-heated by contact with the upper quadrant of the stream of heated gas. When the spray issubsequently moved leftward axially along the dotted line ist, this zone will be additionally pre-heated by the side quad- 60 rant of the annular stream of gas.' Further left-U wardmovementalong the line |41 will bring the zone |56 inthe atomized spray, so that-after two vpre-heating steps the paraiiln, for instance, is .ap-

plied to the zone E56, without permitting any I g.; cooling between the second pre-heating step and the application of parafn., As thespray is 'moved'. lftward a'-further distance along the dotted line I", the vzone |55 will be post-heated by the other sidedqusdrant or the strem of gas.

.i 7 0 $0 also, whemata later period of time, the spray Vis being moved rightward along the dotted line i 75 vthegases near the surface of the ,f` In this embodiment of the invenntion' the arci-,92s.-

stp prevents such solldiication. By post-heat- 10 ingithe zone G56, the paran is maintained in liquid iorm and is forced deeper intothe' pores. As soon as the post-heating has been completed. the heated air in the pores rapidly cools by heat conduction.

deeper-embeddedmortions of the concrete, and

secondarily heat nows to the surrounding atmosphere. The result is that the cooling air con- 1 tracts before the parain vhas solidied, this contraction drawing the param into the pores 20 andthus eecting a much deeper penetration 1 .than hasher'etofore been obtainable. Successive post-heating is desirable in that it tends to further increase this depth oi penetration;

While the temperature of the gas enteringk the 25 main :at can vary over wide :firm-with most materials, I have found it de utilize rather high temperatures in the spraying of materials such-.as paramn. I prefer to utilise a very high-grade parain such, for instance, as 30 f. Borneo paramn, utilizing temperatures of from 550" F. to 660 F., the temperature oftild" F. being found very satisfactory in spraying paramn. However, no xed temperature can be set forth 'for all materials. Thus, in spraying asphalt 35 it is possible to utilizesomewhat lower tempera-` tures, while in spraying sulphur-silica tempera.- tures between 250 F. and 280 F. may be utilized. though best results are obtained with wfas-'s tures from 265 Kit-to 275 F. In sprayingfthe 40 more critical materiala such as sulphur-silica,

'it is very desirable to use a' thermostatio means.

Regardless of the material being sprayed, the temperatures utilized should not exceed the flashpoint of such material. c Alternative spraying devices capable ci' forming the concentric streams are disclosed in Figs. 3,'4, and 5.- Reierrlng particularly .to Fig. 3, I have illustrated'amodied form ojhead struc. ture detachably connected to the-plate i2 in 50 place of the head Si. This embodiment utilizes a tubular construction including a head member A12Enl spaced from a forward member 2M by an outer sleeve' 2M, an inner sleeve 2W also extending between these members and cooperating with v/55 the outer sleeve 202 and denning an annular space 2M. ,The main stream of gas is conducted from the inner tubular member i5 to the inner sleeve 203 so that the main passage in this form of the invention is formed by both of these ele-j ftill ments-this main passage being indicated by the' numeral 2U5. v

' Positioned in this mainpassage is a tube 206 shown as being in the formof an inner venturi similar to the structure .shown in Fig. land be- J y the hakt oWS t0 the 15- teriai to be sprayed is introduced through a passage means 2|5 of the head member 20, the flow being controlled by a valve 2|6. The passage means 2|5 communicates with a pipe means 2|`| disposed in heat-transferring relationship with theggas movingl through the main passage 205. A preferable mode of effecting this result is to form the pipe means 2|'| in the form of a helix extended in the annular space 204. The forward end of this pipe means communicates with the throat of the inner orifice means through a suitable valve 2|8. This valve may be used alternativelywith the valve 2|6. Usually, however, it is sufficient if the valve 2|8 acts as a regulating .f means to control the maximum flow of the material introduced into the inner venturi. Material may be supplied to thepassage means 2|5 from the receptacle 80 in which event a dual heating of the material will be effected, the material being preliminarily heated in the receptacle and being further heated in the pipe means 2|`|. In other instances, the passage means 2|'5 can communicate with a pipe or hose 220 acting .member 23D with a sleeve 23| extending forward therefrom and cooperating in forming the main gas passage, A forward member 232 provides a cavity into which this sleeve extends and provides an opening 233 which converges forf wardly. In this embodiment the tube, such as the tubef68 or206 previously described, it is not in the form of a venturi but comprises a relatively long tube 235 bounding an inner orifice" means 236 at its forward end and cooperating with the opening 233 in defining an outer orifice means 231 of annular shape. This tube 235 is closed atits .rear end by any suitable means, such as a central-member 238, which may serve to support this tube, being in turn supported by an arm 239 of the head member 230 The passage means delivering the material includes in ythis embodiment an inner tube 24| carried by 'the central member 238 and extending forward in the tube 235 to a position beyond one or more openings 242 formed in the tube 235.

In this embodiment the main stream of gas is divided into two streams, one being an annular stream and being discharged through the outer orice means 231, and the other being a stream formed inside the pipe 235 when a portion of the gas moves through the openings 242 and forward through the annular space between the tubes 235 and 24|. The latter stream of gas forcibly withdraws the material from the inner pipe 24| and thus from the passage means, acting to atomize this material as soon as it is discharged from this innerl tube. In this embodiment I have not found it necessary to utlize venturis for purposes of atomization or for producing the concentric streams.

In Fig. 5 is shown a modified hed structure including a head member 250 secured to the plate |2 and providing a nozzle 25| which may be formed integrally therewith. This nozzle provides an opening 252 whichis preferably, though not necessarily, of Venturi shape. The central aior'foaaf,

member 238 and its supporting ar'm 239 are substantially the same as indicatedin Fig. 4, sup porting the tube 235 and the in ner tube 24|. However, the openings 242 in this embodiment are positioned in the intake passage of the venturi so that a portion of the main stream of.

gas moves through these openings into the annular space between'the tubes 235 and 24|. The remaining gas from this main stream is discharged through an outer orifice means 255 between the tube 235 and the walls of the opening 252. Preferably -both ofthe tubes 235 and 24| terminate near the throat of the venturi, very satisfactory results having been obtained by extending the inner tube 24| a slight distance beyond the forward end of the tube 235. The atomizing action is such that an inner stream of subdivided material is projected', being enveloped by a moving stream of hot gas as previously described, atomization taking place at the forward ends of the tubes 235 and 24|. The action of this construction can sometimes be improved by using helically disposed vane means 260 in the main passage. j

The head structures shown in Figs. 4 and 5 can be used for various materials, including the materials previously suggested. They are particularly adapted for spraying such materials as sulphur-silica.

The spraying devices herein described Ican be used at various spacings from the surface to be coated. On the smaller units herein described this distance is usually less than 6 inches, though larger spacings can be used. This spacing depends in part upon the temperature of the surrounding atmosphere andthe Surface to be coated. Usually on hot days or when the surface is already warm the larger spacings can be used to'best advantage, while on cooler days or when the surface is rather cool the smaller spacings are more desirable.

It will be clear that my invention is not limited to the particular embodiments herein disclosed, finding utility in various capacities wherein it is desirable to coat* a surface for waterproong,-protecting, or other purposes. While I have particularly described the spraying of liquids by' atomization or subdivision thereof, my invention can also be used to spray various other materials in powder or granular form, the surrounding stream of gas serving to separate the sprayed material from the surrounding atmosphere. Nor is it necessary to the utility of my invention that coatings of'a penetrating nature be always applied. For instance, the sulphurpenetrate but will bond ous surfaces.

I claim as 'my invention: 1. In a, spraying device of the character devery effectively to variscribed, the combination of t a head structure pro- .viding an opening therein; a tube disposed inv said vsilica previously mentioned willnot materially' tubular member extending rearward from said head structure in 'axial alignmentwith said opening 'of said head structure; heating means surrounding said'tubular member; means for iiowing a stream of gas through said tubular member, said stream being heated by said heating means, a portion of said stream of heated gas iiowing through said tube and another portion of said heatedgas owingaround said tutaami through said annularoriiice means; and means delivering the material to'be sprayed to said tube whereby said material is picked up by said stream of heated gas moving through said tube and is discharged from said inner orifice means, the heated gas owing through 4said annular orice means being discharged in enveloping relationship with said material.

2. In a spraying device of the class described, the combination of: inner and outer tubular` members spaced from each other to define an annular space; means closing one end of said annula space; annular heating lmeans extending into theother end of said annular space to form same into a ytortuous passage one end vof which communicates with said inner tubular member;

, means for deliveringV a stream ofgas through said tortuous passage to be heated by said annular heatingmeans, said` heated gas' discharging from said` tortuous passage into said inner tubular member; orice means `receiving 'the heated gas from said inner tubular member; and` passage means for delivering a material to be sprayed to said heated' gas. i.

. 3.- In a spraying device of the class described, the combination of: 'a body structure providing a chamber; a rearward-extending tubular member attached to said body structure and extending rearward in-said chamber; an annular heating unit around and spaced fromsaid tubular member; means for owing a stream of gas betweenl said heating unit and said tubular member and thence into said tubular membemian atonizing means associated with said body structure and receiving atleast a portion of said heated gas; and means for delivering the material to be 'sprayed to said atomizing means.

, d. A combination as defined in claim 3 includ.

heating means'for said air and means delivering a. portion of the heated air to each of said orifice means; and meansfor. delivering molten paraiiin to saidinn'er orice means whereby vthe inner stream of air 4carries particles of molten parafiin to th surface` to be coated and the stream.' of

heated air moving through said annular orice lmeans forms a protecting envelope for said inner stream during its passage to said'surface.

6. A method-'of applying to a surface a coating of-parain, which method includes the steps of:``

heating 'said Aparaffin until it is molten; `spraying said paraflin -ontosaid surface inmolten condi-,

, A'tionandkin atomized state by moving toward said es. containingatomizedparain; and protecting said stream of atomized vparamn from contact with .4

they atmosphere by surrounding said stream with surface an' inner. stream of low velocity hot air amoving annular envelopeof heated gas owing toward saidsurface in concentric'relation with-- said inner stream of .atomized parailin. i

7.--A method of a. lying to a surface a coat-` f pp contact with` said surface inside said annular stream`of gas by means of a stream of hot air -and inheattransferring relationship therewith 75 ing of paraim which method Vincludes the steps' of: heating said paraffin until itis molten; atom- 75Y icing said molten paraffin; moving'said atomiaed aromas parain while'dsper'sed inta stream of heated air toward said surface from a position spacedtherefrom; and applying heat to said stream of atomized paramn as it hows through space from said position spaced from said surface toward said 5 surface to insure that the atomized parajilln will reach and be deposited on said surface in molten condition. l

8.. A method of applying to a surface 'alcoating of paramn, which method includes the steps of; 10 moving a relatively low-velocitystreani of heated gas through and from a passage towardsaid surface, the impelling pressure in said passage being not in excess of twelve inches of water to eliminate excessive cooling of said stream of gas such 15 as would be caused by excessive expansion after leaving said-'passage when utilizing higher Iimpeiling pressures; entraining in said stream of heated gas molten particles of parain which are carried to said surface 'by said stream of heated 20 gas, any expansion of said stream of heated gas taking place after discharge from said @passage being minimized by said low impelling pressure; and surrounding said stream of Vheated 'gas with a low-velocity concentric stream of hot gas mov- 25 ing concurrently andin contact therewith and of' a temperature above the melting point oi parain.

9. A method of applying to'a surface a coating of material, which method includes the steps of z' 30' heatinga owing stream of gas;- dividing said stream of heatedgas into two concentric inner and outer streams owing concurrentlyA toward said surface; and introducing into and entraining in said inner streamV particles of the mate- 35 rial to be sprayed, which particles are at a temperature slightly below the temperature of saidv heated gas, whereby said inner stream isfslightly cooled to `allow said outer stream of gas to bey somewhat warmer, thereby supplying heat to. said 40 inner stream of gas during movement toward said surface. 1

j of heatedgas andthe lmolten particles of paraffin to successive areas Vof vsaid surface by moving lsaid stream and said molten particles relative to vsaid surface during application of said molten particles to said suracaiwhereby agiven area of said surface is rst pre-heated by saidheated gas on one side of`saidannular stream, then im- 69 mediately receives a deposit of said paramn particlesand is then post-heated by .said locating gas on the other sideV of said annular stream, after which said given area is cooled. by contact with Vthe atmosphere. i.

.,nular stream of non-burning gasheatedto a I temperature above thel melting temperature of 70 v fparaiin toward the-surface to bef-sprayedL and moving molten paramn particles toward and into whereby said particles are heated during such movement.

12. In a spraying device of the character de- `"scribed, the combination of: a head structure having an opening therein; means-for delivering a stream of low pressure non-combustible gas to said opening; means in said opening for dividing said stream of gas into inner and'outer substantially concentric streams, said means including a tube disposed in said opening, said tubev having 1 an annular edge adapted to pierce said stream.l whereby said inner stream may ow through said tube and said outer stream may ow through the space between said tube and the walls Qi said opening; passage means communicating with the interior of said tube; and meansfor delivering to said passagemeans, and thus to said inner stream of gasvmoving through said tube, the material to be sprayed, whereby said material may be picked up by said gas constituting said inner stream and discharged inside said outer stream of gas and against a surface to be coated, the 10W 15. A combination as deined in claim 12, cluding means for heating the stream of gas before it reaches the annular ledge of the tube, and in which the pressure of said stream of gas is not in excess of twelve inches of water.

16. A combination as defined in claim 12, in which the tube is a Venturi tube.

17. A combination as deiined in claim 12, in which the means for delivering the stream of low pressure gas to the opening includes a blower.

1 8. In a spraying device of the character de- I scribed, the combination of: ahead structure providing an opening' therein; a tube disposed in said opening and bounding an inner orlce means, said tube being smaller than said opening in said head structure to provide an annular orice means surrounding said inner orifice means; a tubular member extending from said head structure in axial alignment with said openingoi said structure; means for owing a stream oi.' gas through said Itubular member, a portion of said stream of gas sowing through said tube and another portion of said stream of gas owing around said tube and through said annular oriiice means; heating means adjacent ,said tubular member for heating saidgas beiore'it enters said tubular member;l and means delivering the material to be sprayed to said tube, whereby said material Ais picked up bysaid stream of heated gas moving through said tube and is discharged from said inner oriiice means, .the heated gas flowing through rsaid annular oriilce means being discharged in enveloping relationship with said material.'

19. In a spraying device ofthe class described, the combination of: .a body structure providing a chamber; a tubular member attached to said body structure and extending within said chamber; an annular heating unit around and spaced from. said tubular member; means for iiowing a stream of gas between said heating unit -and said` tubular member and thence into said tubular member; an atomizingimeans associated with said body structure and receiving at leastra portion of said heated gas;, and means for delivering thematerial to be sprayed to said atomizing means.

20. A combination as deiined in claim 19, in-

cluding a heat responsive means in the path of ilow of said hot gas as it moves trom the space .between said heating unit and said tubular member and into said tubular member.

2l. `In a device for spraying material upon a surface, the combination of: an outer venturi providing a throat and a flaredl portion extending from said throat toward the surface to be sprayed; an'in'ner Venturi tube providing a throat and bounding an inner orifice means at one end, said outer'venturi opening-directly to the atmosphere and said inner Venturi tube being within the outer venturi, said inner orifice means being disposed adjacent the throat of said outer venturi,

` said inner Venturi tube being smaller than said outer venturi and cooperating therewith in forniing an annular orifice means; means for yiiowing gas through and from said inner and said annular orifice means to form concentric streams moving through the atmosphere to the surface -to be sprayed; and means for introducing the material to be sprayed into said throat of said of gas discharged from said annular orifice means.

LUDWIG STOESLING.

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