Line purging device
O Umted States Patent 11 1 1111 3,878,579  
 Smith Apr. 22, 1975 1 LINE PURGING DEVICE 3.403.701 l0/l968 Knapp ct al 15/l04.06 R x 3.543.324 I2 1970 K t&#39;l l5 l04.06 R 75 Inventor: Ora 0. Smith, Richton Park. 111. I  
 [73] Assignee: Kraftco Corporation, Glenview, 11]. Primary E.\&#39;aminerEdward L. Roberts Attorney, Agent, or Firm-Fitch, Even, Tabin &amp; [22] F1led. Aug. 17, 1973 Luedeka [2l] Appl. No.: 389,380  
 [57] ABSTRACT 52 us. (:1 l5/104.06 R A line Purging device Comprising a Swab having a 1511 1m. (:1. B08b 9/04 compressible generally cylindrically Shaped body that [58] Field of Search 15/35. 3.51. 104.06 R. terminates at o end in a non-Symmetrical tapering 15/ Q4 137/2 3 section having an off center and blunted nose and that terminates at the other end in a surface lying generally 5 References Ci normal to the axis of the body. A concavity is pro- UNITED STATES PATENTS vided intermediate the ends of the body to facilitate flexure of the device. l.796.338 3/1931 Moore l5/l04.06 R X l,8l4.766 4/1931 Oberhuber l5/3.5 10 Claims, 5 Drawing Figures LINE PURGING DEVICE The present invention relates generally to line purging devices. and more specifically. to a swab of compressible material for use in processing systems employing clean-in-place procedures.  
  As used herein. the term line refers to any conduit or piping for conveying a fluid. Line purging devices in the form of swabs of compressible materials. also known as pigs. are well-known for cleaning lines such as water mains. oil lines or gas lines. Such swabs are typically in the form of bullet-nosed cylinders and are made of open cell. foamed compressible material providing the swab with a compressible and resilient body. The prior art purging devices may further comprise a single or a criss-cross spiral pattern of a hard cast coat ing or of a variety of abrasive coatings to exert a scraping action on the line as a swab travels through. Thus in cleaning lines. such swabs remove deposits from the lines and other foreign matter which may be present.  
  Air or other fluid (either liquid or gas) under pressure is typically applied behind the bullet-nosed swab. and the swab expands to form a seal against the line wall and moves through the line in response to the air or fluid pressure thereby purging the line and at the same time cleaning the walls. The fluid in the line may saturate the purging device and this saturation can facilitate the movement of the device through the line. The swabs are known to have the ability to turn in short radius 90 elbows. to cross tees. to pass through gate and check valves. and to pass through multidimensional lines. Where required. a single swab may be used to pass through the line system more than once. Alternatively. more than one swab may be used in tandem on a single pass through the line system.  
  Although the heretofore known swabs have been successful in purging lines and are capable of navigating around most hindrances in lines. it has been found that the swabs heretofore available have had difficulty with various hindrances. particularly in lines having valves with stems. Such valves are frequently found in sanitary fluid systems. such as dairy. food. and beveraging processing systems where clean-in-place techniques are regularly employed to sanitize the system.  
  While cleansing of sanitary lines can be accomplished in a variety of ways. as by applying compressed air at one end of the line and forcing the contents of the system out at another end and by flushing a suitable liquid through the line. these methods are inefficient; and with expensive products in the line. they can be costly. Accordingly. the use ofa purging device overcomes the inefficiency and costliness provided that it is capable of successfully navigating the hindrances in the line. Of course. entanglement of a swab in the line is inefficient and indesirable.  
  It is a primary object of the present invention to provide an improved line purging device that is more capable of passing through a line having hindrances therein.  
  It is further object ot the present invention to provide an improved line purging device for use in lines having as a hindrance a valve with a stem.  
  It is a still further object of this invention to provide an improved line purging device which provides more efficient and less costly techniques for removing fluids from lines.  
  These and other objects of the present invention will become apparent from the following detailed description and from the drawings in which:  
  FIG. 1 is a side view in elevation of a line purging device constructed in accordance with the principles of the present invention;  
 FIG. 2 is a plan view of the device of FIG. 1;  
  FIG. 3 is a view of a portion of a typical line employing the device of FIGS. 1 and 2;  
  FIG. 4 is a plan view in cross-section along the line 4-4 of FIG. 3 illustrating the device of FIGS. I and 2 moving around a valve stem; and  
  FIG. 5 is a cross-sectional view of the device in the valve taken along the line 55 of FIG. 4.  
  Briefly, the preferred embodiment of the line purging device in accordance with the present invention is shown is FIGS. 1 and 2. The illustrated device can be considered a swab 7 and includes a body section 9 in the general form of a cylinder. The swab 7 is made of an expandible and flexible material which may be a plastic foam material. The body section 9 connects at its front end to a tapering section 11 which terminated in a blunt nose 13. The body section 9 at its rear end is provided with a tail surface 15 lying generally transversely to the longitudinal axis of the body section 9. The tail surface 15 has a generally concave rim 17. A bore 19 is provided in the rear of the body section in coaxial relation with the body. The bore 19 extends forwardly from the concave rim 17. A concavity 21 is provided centrally of the body section 9 intermediate the tapering section 11 and the forward end of the bore l9. The concavity 21 permits increased flexure of the swab 7.  
  As will be seen in detail hereinafter. the structure and configuration of the swab 7 permits it to follow a representative flow path indicated by arrows 27 in a line system illustrated in FIG. 3. Briefly. a detachable launcher 31 may be attached at one end of the line system, and a detachable catcher 33 may be attached at the other end of the line system. A source of pressure such as an air compresssor (not shown) is connected to the launcher 31 by a hose 35. The swab 7 is caused to move through the line system under a force created by the applied compressed air. The swab is caught and retained in the catcher 33, as indicated. The catcher 33 has an outlet 37 to which a hose 39 is shown attached for conducting the purged product from the line system into a suitable container (not shown) that may be separately provided. When substantially all of the product is removed from the line system. the system may then be flush rinsed in a conventional manner to complete cleansing or sanitizing of the system.  
  As shown in the line system in FIG. 3 for illustrative purposes, the swab 7 maneuvers past at least one valve stem 41, a part of the valve 43. The swab also maneuvers through other impeding elements, such as a close radius elbow 45, a tee 47, and a restricted or reduced line portion 49.  
  More specifically, it will be noted in FIG. 1 that the form of the tapering section 11 is non-symmetrical with respect to the longitudinal axis of the swab 7. Also, it will be noted that the blunt nose 13 is disposed somewhat off of the longitudinal axis and in the illustrated embodiment. is above such axis. In the plan view shown in FIG. 2, the blunt nose 13 is generally symmetrical to the longitudinal axis.  
  As shown in FIG. 1. the top of the tapering section 11 is generally convex. as shown at 51, whereas the bottom of the tapering section 11 is generally concave. as shown at 53. This configuration of the tapering section facilitates the navigation of the swab 7 through line systems having a wide variety of impediments in the systems. The blunt nose 13. while shown in plan view as being centered relative to the longitudinal axis. may be off center. In smaller diameter line systems. the blunt nose 13 may be made somewhat sharper.  
  As previously indicated. the concavity 21 ofthe body section 9 is located rearwardly of the tapering section 11. The primary purpose of the concavity 21 is to provide a section of diminished cross-section in the body section 9 intermediate its ends. Such a diminished section facilitates body flexure. Such an accomodation is important as will be seen hereinafter. The precise form of the concavity 21 may vary without departing from its functional purpose. although it has been found that if the concavity 21 takes the form of a ring of uniform depth that completely encircles the body section 9. the swab 7 will not perform satisfactorily in the line system. In other words. the concavity 21 should provide nonsymmetrical relief in the surface of the body section 9 relative to the longitudinal axis. While the concavity 21 is shown in FIG. 1 as being located in the top of the cyclindrical body section 9. its location is not restricted to such location. The concavity 21 could be located. for example. in the bottom surface or side of the body section 9. Also. the concavity will be disposed forwardly of the bore 19 in the tail surface 15.  
  Referring now to FIG. 3 conventional swabs heretofore known have had difficulty in passing an obstacle such as the stem 41 of the valve 43 in the illustrated line system. The present swab 7. however. passes such an obstacle in the manner hereinafter described with particular reference to FIGS. 4 and 5.  
  In FIG. 4. the swab 7 is illustrated in a position halfway through the valve 43. While not wanting to be bound by any precise theory. one possible explanation for the ability of the swab 7 to navigate a valve having a stem lies in the combination of its structure and the behavior of fluids in the line. The compressible body generally in the form of a cylinder having a nose 13 that is eccentric with respect to the axis of the body section 9 and the concavity 21 to provide improved flexure is believed to give the unusual features to the swab 7.  
  The blunt nose 13 of the illustrated swab 7 is forced into the line as the swab is driven through the system by pressure. The fluid in the line system will tend to resist movement of the swab 7. The resisting fluid applied against the tapering section 11 of the swab 7. and more particularly the force exerted against the concave surface 53, coupled with the eccentric location of the nose 13 urges the nose 13 away from the longitudinal axis.  
  During unimpeded travel of the advancing swab 7. it may assume any arbitrary rotational position internally of the line. Upon approaching an obstacle such as the stem 41, however. the fluid divides into opposing channels 67 and 69 on either side of the stem as best seen in FIG. 5. It is believed that the nose 11 will tend to follow one channel around the stem. Thus. as the swab 7 approaches the valve stem 41, if the nose 13 is not already oriented to generally coincide with the fluid channel on one side or the other of the stem. the swab will tend to rotate either clockwise or counterclockwise to the closest point where the nose 13 will generally follow the fluid flow around the stem.  
  The pressure applied to the tail surface 15 propels the swab 7 through the line system and it is important at all times that some portion of the swab 7 is expanded against the inner wall of the line system to form a seal. Otherwise. the pressure would equalize around the swab. and there would be no force propelling the swab through the line system. Thus in FIG. 4, where the swab 7 is illustrated as being in the process of bypassing the stem 41. a seal is being maintained by the portion of the body section 9 rearwardly of the concavity 21. When this seal is lost. the portion of the body section 9 forward of the concavity 21 has established a seal in the line system. Stated otherwise. the second seal is established before the first seal is lost. Thus. as the swab 7 passed through the valve 43. some portion of the full diameter of the body 9 is always forming a seal so that the pressure is maintained behind the swab 7. It is important. therefore. that the length of the swab 7 be sufficient to span the valve 43 in the manner just described. In this connection. it is preferable that the length of the swab be at least about three times the diameter of the swab to provide the adequate length.  
  As before pointed out. the concavity 21 is provided to accomodate flexure of the body section 9. Such flexure eases the passage of the swab 7 through the valve 43. It is believed that any symmetrical ring formed in the body section 9 permits a collapse of the body upon itself when under pressure. and that such collapse breaks the seal. causing pressure equalization on either end of the swab and a consequent loss of driving force. Accordingly. the concavity 21 desirably does not completely encircle the body.  
  The rear end of the swab includes the tail surface 15 comprising the concave rim 17 which connects to the bore 19. Such formation of the tail surface 15 permits it to expand more readily under pressure to form a seal. The seal is made even more effective by the provision of the bore 19. Preferably the diameter of the bore 19 does not exceed one-half the diameter of the body section 9 and the depth of the bore does not exceed the diameter of the body section 9.  
  The line system is intended to illustrate a system employing clean-in-place techniques. Thus. the components of the system are easily separable from one another. and the entire system can be easily dismantled for cleansing and sanitizing. A typical system may include. for example. lineal feet of pipe or line. and it has been estimated that a nominal Z-inch I.D. line may contain one and one-fourth pounds of product per lineal foot. Such weight of product may vary. of course. with the specific product being handled in the line system. It can be seen. nonetheless. that each time a line system is shut down for cleaning a considerable amount of product remains in the line, and it is desirable to salvage this product to prevent economic waste and to avoid disposal of it through a sewer system.  
  In using the present invention. the launcher 31 is attached at one end of a line system. such as the illustrated line system. that is to be purged of product. The launcher 31 is clamped by any suitable means. such as by the clamp 57. A swab 7 is inserted within the launcher. Connected to the launcher is a source (not shown) of fluid pressure. This fluid may be compressed air as utilized in the preferred embodiment or a suitable liquid and is brought in communication with the launcher 31 by means of the hose 35. One example of pressure that has been used in the preferred embodiment is plant compressed air at about 80 to about 100 pounds per square inch. although it has been found that the present swab will work in a line system with as little pressure as 15 pounds per square inch driving it through a line. The pressure depends primarily on the viscosity of the product being purged and the speed with which it is desired that the swab travel. These determinations are not difficult for one skilled in the art to make. Normally, a system can be purged in a matter of seconds.  
  At the opposite end of the line system being purged, the catcher 33 is attached by a suitable means. such as the clamp 57. The catcher includes a cap 63 which al lows access for removal of the swab 7 retained in the catcher. As the swab 7 advances through the line system. it pushes ahead of it the product within the system. The fluid product 64 flows from the catcher 33 (FIG. 3) through the outlet 37 into the hose 39. The hose 39 further directs the product into a suitable container (not shown) for retrieving the purged product.  
  Preferably. the swab 7 is made of an expanded open cell plastic material, such as polyurethane foam. which is compressible and expandible. The swab 7 in the preferred embodiment is a polyurethane foam having a density of from about 8 to about 12 pounds per cubic foot.  
  Heretofore. some of the known line purging devices have been made of material having a low density. and as a consequency. these swabs are made considerably larger in diameter than the line system in which they are utilized. Use of the more dense polyurethane foam indicated above results in improved life. increased strength and a swab of a diameter approximating the l.D. of the line system in which it is to be used. Preferably. the body section diameter of the illustrated swab 7 is about one-fourth inch greater than the ID. of the line in which it is to operate. Thus. in a line having a nominal two-inch l.D.. a swab having a two and onefourth inch diameter is desired.  
  Once the swab 7 is inserted in the launcher 31 and the pressure is applied to the tail surface 15, the swab forms a seal and moves rapidly through the line system even through the system includes many inpeding elements. such as the valve stem 41, the 90 elbow 45, the tee 47 and the reduced diameter portion 49. Where. as in the illustrated example of the tee 47,21 valve 65 closes the flow straight through the base of the tee. the swab 7 follows the fluid flow in the direction indicated by the arrows 27 and accomplishes the right angle turn in the tee. Of course. there are practical limits to the amount of reduction in the reduced portion 49 the swab can tolerate. A specific example of a system in which the preferred embodiment has been utilized is a system consisting primarily of 2-inch l.D. lines wherein the reduced portions are 1 /2 inch l.D.  
  Once the swab has completed its trip in the manner just described, most of the product has been removed (purged) from the system. the product thereby being salvaged. The system may then be further cleansed and sanitized in a conventional manner.  
 Thus, there has been provided in accordance with the present invention a line purging swab capable of use in a line system employing clean-in-place techniques where it is desirable to salavage the product remaining in the line at the time of shut-down. The swab 7 of the invention is of a particular form which allows it to pass readily through impeding elements of a typical line system which includes valves having stems.  
  While the invention has been described in connection with a preferred embodiment, many alternatives, modifications. and variations may be apparent to those skilled in the art in view of the foregoing description. Accordingly. it is intended to embrace all such alternatives. modifications, and variations as fall within the spirit and scope of the appended claims.  
  Various features of the invention are set forth in the following claims.  
 What is claimed is:  
  l. A line purging swab comprising a compressible body section, said body section being generally cylindrical in shape, said body section having a tapering section at one end having a blunt nose, said body section having a tail surface at the other end. and said body section having a concavity in its surface to facilitate flexure. the inmost part of said concavity extending transversely of but not completely encircling said body section.  
  2. A swab in accordance with claim 1 wherein said concavity is positioned intermediate said ends.  
  3. A swab in accordance with claim 1 wherein the blunt nose is eccentric to the longitudinal axis of the body section and wherein the upper surface of the tapering section is convex and the lower surface is concave.  
  4. A swab in accordance with claim 1 wherein said compressible body comprises open cell polyurethane foam.  
  5. A swab in accordance with claim 4 wherein said polyurethane foam is of a density between about 8 and about 12 pounds per cubic foot.  
  6. A swab in accordance with claim 1 wherein said tail surface is recessed into the body section.  
  7. A swab in accordance with claim I wherein said tail surface is formed with a concave rim which connects to a bore extending inwardly of said body section.  
  8. A swab in accordance with claim 7 wherein the diameter of said bore does not exceed one-half the diameter of said body section and the depth of the bore does not exceed the diameter of said body section.  
  9. A swab in accordance with claim 1 wherein the length of the swab is at least three times the diameter of the cylindrical portion of the body section.  
  10. A line purging swab comprising a compressible body section, said body section being generally cylindrical in shape. said body section having a tapering section at one end having a blunt nose, the upper surface of the tapering section being convex and the lower surface thereof being concave, the blunt nose being eccentric to the longitudinal axis of the body section, said body section having a tail surface at the other end, and said body section having a concavity in its surface to UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT NO. 1 3,878,579 DATED April 22, 1975 INVIENTOR(S) I Ora O. Smith It is certified that error z appears in the above-identified ptent and that said Letters Patent are hereby corrected as shown below:  
 Col. 1, line 44, &#34;beveraglng&#34; should&#34; be -beverage-.  
  Col. 2, line 17, &#34;is&#34; should be -in-.  
 C01. 2, line 23,&#34;te1fminated&#34; should be terminates.  
 &#39;Col. 4, line 17, &#34;passed&#34; should be passes-.  
 Col. 5, line 6, the numeral &#34;15&#34; should not be in bold print.  
 Col. 5, line 31, &#34;consequency&#34; should be -conseque-nce.  
 Col. 5, line 45, &#34;through&#34; should be though-.  
 Col. 5, line 45, &#34;inpeding&#34; should be -impeding-.  
 Col. 6, line 3, &#34;salavage&#34; should be salvage--.  
 Signed and Scaled this twenty-third Day Of December 1975 [SEAL] A ttes r:  
 RUTH C. MASON C. MARSHALL DANN 8 ff Commissioner ufPalenls and Trademarks