US3123455A

US3123455A - Spray booth

Info

Publication number: US3123455A
Authority: US
Publication date: 1964-03-03
Anticipated expiration: 1981-03-03

Description

March 3, 1964 J. A. PAASCHE SPRAY BOOTH (SELF CLEANING) 4 Sheets-Sheet l INVENTOR Qflaa'ce Jim; v

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Filed Aug. 5, 1960 March 3, 1964 J. A. PAASCHE SPRAY BOOTH (SELF CLEANING) 4 Sheets-Sheet 2 Filed Aug. 5. 1960 INVENTOR 5726 dj aa5cke vfiw/w MW ww HHMWHHWWWHHI WHUWWHWH Hwnwnnmnmwmwnw 5 5 i Mardl 1964 J. A. PAASCHE SPRAY BOOTH (SELF CLEANING) 4 Sheets-Sheet 3 Filed Aug. 5, 1960 II/IIIII'IIIIII'I INVENTOR- fiaace March 1964 J. A. PAASCHE SPRAY BOOTH (SELF CLEANING) t N NW m N% 11 I ll H w & {H1111 M I I i I I i \n p Q. mm u w v a 7 Filed Aug. 5, 1960 United States Patent 3,123,455 SPRAY BOOTH (SELF CLEANENG) liens A. Paasche, 310 Greenleaf, Wilmette, Ill. Filed Aug. 5, 1960, Ser. No. 47,849 Claims. ((Il. 55-228} The present invention relates to spray coating booths which define working space within which objects are positioned and coated with atomized droplets of a coating liquid directed onto the objects from spray guns or the like. In such spray coating operations, there is almost invariably an overspray of atomized droplets of coating material which do not impinge upon the object or objects being coated. This overspray tends to collect on the structure defining the working space in which the coating is performed and contaminates the atmosphere surrounding the spraying operation. This contamination of the environment can create many problems and undesirable conditions, some of which are hazardous.

To minimize contamination of the environment by the overspray from such spray coating operations, spray booths have been developed which make use of water curtains to shield the working space defining structure from the overspray and which continuously scavenge the working space with air that is subsequently washed to remove the entrained particles of coating material. The maintenance of the protective curtains or" water in such booths and the washing of the scavenging air has required the circulation of wash water or scavenging liquid through the booths at a high volumetric rate. To prevent the water used as a scavenging liquid from becoming overcontaminated with entrained coating material it has been necessary to provide some means for removing the coating material from the water circulated through a spray booth of this character.

One object of the invention is to provide a spray coating booth incorporating an improved construction and utilizing novel features of operation to provide worthwhile advantages in the construction and use of the booth.

Another object is to provide an improved spray coating booth of the character recited in which an improved construction provides for a more eificient and highly advantageous removal of coating material from the scavenging liquid, which is circulated through the booth to prevent contamination of the environment by the overspray from spraying operations in the booth.

A further object of the invention is to provide a spray coating booth of the character recited in which a more efficient cleaning of coating material from the scavenging liquid is achieved in an improved manner, which simplifies the construction and minimizes the size of the liquid cleaning structure while at the same time greatly increasing the volumetric rate at which liquid can be cleaned and circulated through the booth.

A more specific object is to provide an improved spray coating booth as recited in the preceding objects in which a fully effective filtering of the entire flow of scavenging liquid through the booth is provided in a manner which necessitates actual filtering of only a fraction of the liquid flow through the booth.-

Other objects and advantages will become apparent from the following description of the exemplary embodiment of the invention illustrated in the drawings, in which:

FEGURE l is a perspective view of the spray coating booth forming the illustrated embodiment of the invention, certain portions of the booth structure being broken away for clearness in illustration;

FIG. 2 is a front elevational view of the booth shown in FIG. 1;

FIG. 3 is a transverse sectional view taken along the line 33 of FIG. 2;

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FIG. 4 is a perspective view of a typical panel flushing nozzle used in the booth;

FIG. 5 is a fragmentary sectional view taken along the line 5-5 of FIG. 1;

FIG. 6 is a fragmentary sectional view taken along the line 66 of FIG. 5;

FIG. 7 is a fragmentary sectional view taken along the line 7-7 of FIG. 1; and

FIG. 8 is a fragmentary perspective view taken along the line 88 of FIG. 1.

eferring to the drawings in greater detail, the spray booth 10 forming the exemplary embodiment of the invention illustrated defines an internal working space 12, FIGS. 1-3, within which a typical article 14 to be coated is positioned by any suitable means (not shown) and coated with a coating liquid atomized and directed toward the object by a spray gun to. As shown, the working space 12' has a rectilinear form and is open only along the front side of the booth. This space is defined by booth structure including a ceiling 18, a floor panel 29, a rear side or back panel 22, and two side panels or

end walls

24, 26.

Low velocity coating particles which do not impinge on the article being coated are swept from the working space 12 by a current of scavenging air which is sucked through the working space into an air Washer 28 at the rear side of the booth ill.

The air washer 28 extends horizontally along the full length of the booth ill and is separated from the working space M; within the booth only by the rear panel 22: which extends downwardly and rearwardly, FIG. 3, to the lower edge of the rear panel, which terminates a substantial distance above the level of the floor panel 20. This provides a longitudinal opening 3% between the rear lower portion of the working space 12 and the bottom of the air washer 28.

Air is drawn up through the washer 28 by an exhaust fan 32 which causes the air to flow through a transverse diffuser 34 formed by fenestrated baflling extending the full length of the washer just above the lower edge of the table 22. A finely divided spray of water is played downwardly onto the diffuser 34 by means of a series of nozzles 36 depending from a longitudinal manifold 38 extending through the washer above the diffuser. Droplets of water entrained in the air stream are removed from the air by a horizontal series of air drying bafiles 46 which overlie the manifold 38.

Irnpingement of particles of coating material onto the floor panel 20 and onto the upright panels Z2, Z4 and 26 bounding the working space '12 is prevented by a continuous flushing of these panels with moving sheets or curtains of water.

Thus, the floor panel 29' is continuously flushed with water directed onto the panel from a series of nozzles 42. projecting rearwardly from a horizontal manifold 44 extending along the front edge of the bottom panel. The

upright panel

22, 24, and 26 are flushed with Water directed downwardly onto these panels by nozzles 46 depending from

horizontal manifolds

48, 50, 52 for the respective upright panels.

Each of the nozzles 42, 4-6 is designed to direct a flat diverging stream of water onto an adjacent portion of the coacting panel. A typical nozzle 46 is illustrated in FIG. 4. As shown it is flattened at its projecting end and shaped to define a generally flat outlet 54 for projecting a flat stream of water. The streams of water from adjacent nozzles merge together to form continuous curtains of water flowing over the panels.

The bottom panel 2-6 is inclined rearwardly to discharge flushing water from the working space 12 into a longitudinal runway 56 formed by a longitudinally inclined bottom 58 in the washer 29, which is located below the rear edge of the bottom panel 2% as shown in FIG. 3 and inclined longitudinally toward one end of the booth. The water which is collected into the channel 56 from the Washer 28 and from the working space defining panels is directed into a fiow channel 60, FIGS. 1 and 5-7, designed to produce a generally nonturbulent, laminar flow pattern in the stream of liquid passing through the channel.

Preferably, the channel 60 is disposed in overlying relation to an elongated reservoir 62 and comprises two vertical side walls 64, 66 which extend upwardly from a fiat plate 68 defining the bottom of the channel.

The channel 6t} is turned at a right angle to the runway 56 and extends forwardly from one end of the runway along one end of the booth as shown in FIG. 1. The rear portion of the channel wall 66 is curved progressively toward the washer 28 to connect with the rear side edge of the washer at the outlet of the runway 56.

scavenging water is discharged from the runway 56 into the channel 66' where it is turned by the wall 6t) to flow along the length of the channel. The bottom 68 of the channel is inclined downwardly at a small angle in the forward direction to provide a controlled velocity of flow of liquid in the channel.

As the liquid flows forwardly in the channel 60 in a generally nonturbulent manner, the coating material entrained in the scavenging liquid tends to concentrate in the upper portion of the flow stream.

The upper portion of the liquid stream in the channel 60, in which the entrained coating material is concentrated, is segregated from the underlying portion of the stream, which is relatively clean and uncontaminated with entrained coating material. This is accomplished by means of a skimmer or a separator 70 which defines a horizontal flow dividing or separating edge '72, FIGS. 5 and 7, that is supported in transverse vertically spaced relation to the channel bottom 68 a short distance ahead of the outlet end of the channel. The separator edge 72 extends substantially across the entire width of the channel 60 and is somewhat inclined upwardly and rearwardly at its leading edge to effect an upward displacement of an upper stratum 74 of the liquid flow stream in the channel 60. The portion of the channel fiow stream which passes under the separator edge *72 is discharged from the outlet end of the channel directly into the underlying reservoir 62 as illustrated in FIGS. 5 and 7.

The ratio of the volume of liquid flowing across the separator edge 72 relative to the volume of liquid flowing under this edge can be adjusted by adjusting the vertical spacing of the edge 72 from the channel bottom 63. This is accomplished by means of vertically adjustable supports 76, 78 for the forward end of the separator 70, which supports the leading separator edge 72.

Rearwardly of the edge 72, the separator '70 defines a liquid collecting and cleaning basin 80 which receives the liquid flowing into the separator across the separator edge 72. The bottom of the liquid collector or cleaning portion 80 of the separator 70 is formed by a generally flat metallic filter 82. The filter 82 extends beyond the runway 60 in overlying relation to the reservoir 62 and is supported along its respective edges by three side walls 84 of the separator 7t? and by a transverse support bar 86 extending across the forward end of the separator at the rear of the separator edge 72 as shown in FIG. 7. The water in the liquid flowing across the edge 72 into the collecting basin 8% immediately flows down through the filter 82 into the reservoir 62. The coating material entrained in the liquid is retained by the filter 82 and collects to form a sludge which is supported and prevented by the filter from dropping into the reservoir.

The separator 7-0 is designed to be lifted from its support on the upper edge of the reservoir 62 and dumped to remove the sludge collected on the filter screen 82.

A pump 90 driven by an electric motor 92 pumps scavenging water from an intake 96 in the reservoir 62 into the previously described manifolds leading to the nozzles 36 in the air washer and the flushing nozzles 46 for the working space defining panels.

Even though only a fraction of the liquid circulated through the booth is filtered, the concentration of the entrained coating material in that portion of the liquid which is filtered provides an efiective and highly satisfactory removal of coating material from the circulating scavenging fluid. This makes for greater efficiency in operation and provides for circulation of liquid at a high volumetric rate while at the same time minimizing the size and simplifying the construction of the entire installation, including the means used to clean the scavening liquid.

It will be appreciated that the invention is not necessarily limited to use of the particular construction illustrated but includes the use of variants and equivalents within the scope of the invention as defined in the claims.

The invention is claimed as follows:

1. Apparatus for use in the spray coating of objects, comprising, in combination; means defining an at least partially enclosed spray coating space and including a rearwardly inclined lioor panel, a rear panel, and two end panels; means defining an air washer separated from said spray space by said rear panel, said rear panel being inclined downwardly and rearwardly and terminating above the level of said floor panel to provide communication between the lower rear portion of said space and said air washer, means for moving air from said space through said washer to exhaust, said washer including washing liquid spray means, a diffuser located upstream of said spray means with respect to the flow of air through said washer and air drying means located downstream of said spray means with respect to the air flow through the Washer, flushing nozzle means arranged to direct curtains of washing liquid across said space defining panels, a runway in the bottom of said washer arranged to collect liquid discharged from said air washer spray means and from said flushing nozzle means, means defining a flow channel arranged to receive a continuous stream of washing liquid from said runway, said channel being designed to provide a generally laminar flow of liquid therethrough, means forming a generally horizontal separator edge extending transversely across said channel in spaced relation to the bottom thereof to effect a division of the liquid stream flowing through said channel, means for adjusting said separator edge vertically to adjust tie vertical position at which the channel flow stream is divided, reservoir means arranged to collect liquid flowing from said channel from below said separator edge, filtering means arranged to receive liquid flowing across said separator edge and filter entrained coating material therefrom and return the filter liquid to said reservoir, and pumping means for supplying liquid from said reservoir to said spray means and said flushing nozzle means.

2. Apparatus for use in the spray coating of objects, comprising, in combination; means defining an at least partially enclosed spray coating space and including a floor panel, a rear panel, and two end panels; means defining an air washer situated alongside said space and communicating with said space, means for effecting movement of air through said space and through said washer, said washer including means for spraying washing liquid into the air flowing through the washer, flushing nozzle means arranged to direct curtains of washing liquid across said space defining panels, a runway in the bottom of said washer arranged to collect liquid discharged from said spraying means and from said flushing nozzle means, means defining a flow channel arranged to receive a continuous stream of washing liquid from said runway, said channel defining means having a smooth construction designed to provide a substantially laminar flow of liquid therethrough, means forming a generally horizontal separator edge extending transversely across said channel in spaced relation to the bottom thereof to efifect a division of the liquid stream flowing through said channel, means for effecting a vertical adjustment of said separator edge with respect to the bottom of said channel to vary the ratio of the liquid flowing over and under said separator edge, filtering means arranged to receive liquid flowing across said separator edge and filter entrained coating material therefrom, and means for returning to said spraying means and to said flushing nozzle means liquid filtered by said filtering means and liquid flowing from said channel from below said separator edge.

3. Apparatus as set forth in claim 2 and further including means supporting said filtering means for quick removal thereof.

4. Apparatus as set forth in claim 3 wherein the means for supporting the filtering means comprises a plurality of outwardly disposed means adjacent the upper portion of said filtering means and having downwardly disposed abutment surfaces engageable with fixed abutment sur- 6 faces adjacent said filtering means for supporting said filtering means in suspended position.

5. Apparatus as set forth in claim 4 wherein the downwardly disposed abutment surfaces comprise the lower ends of screw threaded members for adjusting the height at which said filtering means is suspended, and also comprising in part the means for effecting vertical adjustment of the separator edge.

References Cited in the file of this patent UNITED STATES PATENTS 1,709,291 Vidler Apr. 16, 1929 2,086,514 Saunders et al. July 6, 1937 2,557,064 Alexander June 19, 1951 2,660,317 Mork et al. Nov. 24, 1953 2,788,954 Paasche Apr. 16, 1957

Claims

1. APPARATUS FOR USE IN THE SPRAY COATING OF OBJECTS, COMPRISING, IN COMBINATION; MEANS DEFINING AN AT LEAST PARTIALLY ENCLOSED SPRAY COATING SPACE AND INCLUDING A REARWARDLY INCLINED FLOOR PANEL, A REAR PANEL, AND TWO END PANELS; MEANS DEFINING AN AIR WASHER SEPARATED FROM SAID SPRAY SPACE BY SAID REAR PANEL, SAID REAR PANEL BEING INCLINED DOWNWARDLY AND REARWARDLY AND TERMINATING ABOVE THE LEVEL OF SAID FLOOR PANEL TO PROVIDE COMMUNICATION BETWEEN THE LOWER REAR PORTION OF SAID SPACE AND SAID AIR WASHER, MEANS FOR MOVING AIR FROM SAID SPACE THROUGH SAID WASHER TO EXHAUST, SAID WASHER INCLUDING WASHING LIQUID SPRAY MEANS, A DIFFUSER LOCATED UPSTREAM OF SAID SPRAY MEANS WITH RESPECT TO THE FLOW OF AIR THROUGH SAID WASHER AND AIR DRYING MEANS LOCATED DOWNSTREAM OF SAID SPRAY MEANS WITH RESPECT TO THE AIR FLOW THROUGH THE WASHER FLUSHING NOZZLE MEANS ARRANGED TO DIRECT CURTAINS OF WASHING LIQUID ACROSS SAID SPACE DEFINING PANELS, A RUNWAY IN THE BOTTOM OF SAID WASHER ARRANGED TO COLLECT LIQUID DISCHARGED FROM SAID AIR WASHER SPRAY MEANS AND FROM SAID FLUSHING NOZZLED MEANS, MEANS DEFINING A FLOW CHANNEL ARRANGED TO RECEIVE A CONTINUOUS STREAM OF WASHING LIQUID FROM SAID RUNWAY, SAID CHANNEL BEING DESIGNED TO PROVIDE A GENERALLY LAMINAR FLOW OF LIQUID THERETHROUGH, MEANS FORMING A GENERALLY HORIZONTAL SEPARATOR EDGE EXTENDING TRANSVERSELY ACROSS SAID CHANNEL IN SPACED RELATION TO THE BOTTOM THEREOF TO EFFECT A DIVISION OF THE LIQUID STREAM FLOWING THROUGH SAID CHANNEL, MEANS FOR ADJUSTING SAID SEPARATOR EDGE VERTICALLY TO ADJUST THE VERTICAL POSITION AT WHICH THE CHANNEL FLOW STREAM IS DIVIDED, RESERVOIR MEANS ARRANGED TO COLLECT LIQUID FLOWING FROM SAID CHANNEL FROM BELOW SAID SEPARATOR EDGE FILTERING MEANS ARRANGED TO RECEIVE LIQUID FLOWING ACROSS SAID SEPARATOR EDGE AND FILTER ENTRAINED COATING MATERIAL THEREFROM AND RETURN THE FILTER LIQUID TO SAID RESERVOIR, AND PUMPING MEANS FOR SUPPLYING LIQUID FROM SAID RESERVOIR TO SAID SPRAY MEANS AND SAID FLUSHING NOZZLE MEANS.