Abstract:
The present invention provides apparatus and method for sample acquisition from an active flow of mixed powder material being transferred from a blender. The apparatus includes a sleeve that is assembled co-axially to a discharge port of the blender and a number of sample collectors which each include a shaft with sample cavities and a tube that is rotatable around the shaft for exposing and covering the cavities. The sample collectors are alternately inserted through a bearing collar into the sleeve. The tubes are plugged at their respective outer ends to prevent accidental removal from the sleeve. The method includes inserting and opening each of the sample collectors in turn and removing the collected samples for analysis.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to the field of sampling devices and methods for mixed bulk material, and more particularly to sampling devices and methods for mixed powder ingredients for pharmaceutical preparations.  
         BACKGROUND OF THE INVENTION  
         [0002]    In the manufacture of dosage forms, in the pharmaceutical, food and chemical industries, e.g. tablets, capsules, permeable pouches, cans etc., active and inactive ingredients are blended in a suitable blender. Such blends of materials are routinely sampled and tested for homogeneity. Blended bulk materials may be liquid, powder, or a suspension of a powder in a liquid. A proper sampling technique requires unit-dose or bulk quantity sampling to be acquired from different areas of the batch, e.g., top, middle and bottom of the blender or storage container. A unit-dose sample is defined as a quantity of mixed material that is of sufficient size to provide one dose of the active ingredient, whereas a bulk sample is defined as a sample size large enough to provide multiple doses of the active ingredient. Conventionally, samples are obtained by inserting a tubular sampling device having multiple cavities into a batch of mixed materials in the blender. However, such a sampling procedure disturbs the blend during insertion by creating localized pressure spots, thus affecting the test results. This is especially true in case of powder blends. In addition, this sampling technique requires samplers of different lengths to accommodate different size blenders or storage containers. Further, in closed flow streams of powder from a blender or container, there is no provision for compacting the samples into tablets or collecting the samples directly into gelatin capsules in order to eliminate or reduce the post-sampling error caused by transfer handling of small quantities of loose powder.  
           [0003]    U.S. Pat. No. 5,974,900, issued on Nov. 2, 1999 to the present inventor, describes a manually operated stream sampling device and method. This device does offer the possibility of compacting the powder samples into tablets or collecting the samples directly into gelatin capsules. However, this device can be used only with open streams of material, and it is desirable to keep mixed powder materials in closed streams to avoid spreading powder dust into the ambient atmosphere.  
           [0004]    U.S. Pat. Nos. 5,440,941, 5,337,620 and 6,339,966 each disclose a tube-and-shaft type sampling device as may be employed in the invention described and claimed herein. Each of these patents is incorporated herein in its entirety by reference.  
           [0005]    The present invention offers the following advantages over the currently available samplers: (a) the sampler does not have to be inserted into the powder bed; (b) a closed stream of material may be sampled without exposing personnel to powder dust; (c) unit-dose samples may be obtained and processed into the form of tablets or capsules (d) multiple sample collectors are provided for efficiency; and (f) the devices are easily assembled, disassembled, operated and cleaned.  
         SUMMARY OF THE INVENTION  
         [0006]    The present invention is a sampling device and a method for obtaining samples from a falling closed stream of mixed material. The sampling device consists of a sleeve, a guide ring and one or more sample collectors.  
           [0007]    The sleeve has holes on its top flange for being bolted to a discharge port of a blender or storage container. The bottom flange of the sleeve is formed to engage a flow skirt to convey the powder material into a drum or a bin without distributing any dust into the surrounding environment. The mixed powder flows through a sleeve formed with one or more radially aligned holes adapted for inserting a number of collectors.  
           [0008]    The guide ring is formed with radially aligned holes on its side surface to match the holes on the cylinder&#39;s surface. Collectors are guided through these holes to retrieve samples. Each of these holes is configured to prevent the sampler shaft from rotating  
           [0009]    Each collector has an outer tube and an inner shaft and an end piece. The outer tube and the inner shaft have corresponding openings. The inner shaft and the outer tube each have a handle so that they can be rotated individually to open and close sample-collection cavities. The end piece has a curvature that matches the inner surface of the sleeve so that the falling powder material is minimally disturbed. The end piece is larger than the hole in the sleeve to prevent unintended removal. The tube is turned to expose holes in the shaft and collect sample material, and turned back to the original position, to close the dies as described in U.S. Pat. Nos. 5,337,620 and 5,440,941, noted above. The collector shaft may be modified to accommodate empty gelatin capsules instead of holes or sample dies. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]    [0010]FIG. 1 is a side elevation view of a blender to which the sampling device of the invention is mounted.  
         [0011]    [0011]FIG. 2 is a perspective view of a sleeve of the invention sampling device.  
         [0012]    [0012]FIG. 3 is a top plan view of a collar adapted for being mounted around the sleeve of FIG. 1 with a plurality of collectors assembled thereto.  
         [0013]    [0013]FIG. 3A is an enlarged segmented view similar to that in the dashed circle of FIG. 3 with the sleeve tube added for detail.  
         [0014]    [0014]FIG. 4 is a top plan view of the collar of FIG. 3 shown in opened condition without the collectors.  
         [0015]    [0015]FIG. 4A is a section view taken along line  4 A- 4 A of FIG. 4.  
         [0016]    [0016]FIG. 5 is an exploded perspective view of the collector shown in FIG. 3, comprising a tube with an end cap, a shaft, and a plurality of dies.  
         [0017]    [0017]FIG. 6 is a diagrammatic representation of the top of the invention sleeve showing the location from which samples are obtained.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0018]    The following description depicts the preferred embodiment as illustrated in the accompanying drawing figures. The described embodiment is provided as an example, not a limitation, of the principles of the invention.  
         [0019]    Referring now to FIG. 1, a commercial tumbling blender  10 , as is known in the trade, is shown in upright orientation at the termination of the blending operation during which blender  10  is rotated, or tumbled, around shaft S to thoroughly mix powder ingredients to a homogeneous batch. The bulk material, typically a powder, consists essentially of active and inactive components to be mixed together. The speed of rotation of the blender and the length of the tumble cycle depends upon the tumbler geometry and capacity as well as the properties of the components being mixed. Blender  10  is fitted with a discharge port  12  having a discharge valve  14  by which the mixed batch may be allowed to flow out of blender  10 .  
         [0020]    The apparatus of the invention is generally depicted as sampler  20 , comprising sleeve  24  and collectors  60 , to be described in detail below. An upper flange of sleeve  24  is attached by means of bolts or otherwise, to discharge valve  12 . A shroud  16  is mounted to encompass a lower end of sleeve  24  so that the mixed powder material is discharged from blender  10  into receptacle  18  without sending dust into the surrounding environment. The relative size of illustrated blender  10  and sampler  24  is not intended to represent actual equipment. Sampler  20  may connect to other supply apparatus, such as a duct or storage tank.  
         [0021]    [0021]FIG. 2 shows a detail of sleeve  24  in perspective view. Sleeve  24  is formed with a circumferential wall  29 , an upper flange  26  and a lower flange  28 . Circumferential wall  29  defines a throat portion  30 , having axis  31 , through which the mixed bulk powder materials are conveyed following the blending operation. Upper flange  26  is formed with a plurality of bolt holes  32  which match with the location of a similar set of bolt holes in the under side of discharge port  12  (FIG. 1). Lower flange  28  is provided and sized to securely hold shroud  16  as described above. One or more collector holes  34  are formed through circumferential wall  29  in orientations so that each is along a radius of throat  30 . As will be noted below in reference to FIG. 3, collector holes  34  are uniformly spaced around the periphery of circumferential wall  29 . Sleeve  24  is preferably formed of an inert, easily cleanable material, for example stainless steel.  
         [0022]    Referring now to FIGS. 3 and 4, a guide ring  42  depicted in closed and open condition, respectively. Guide ring  42  is split into two hemi-rings  42   a  and  42   b . The two hemi-rings  42   a  and  42   b  are connected at a mutual end by hinge  54  and are closeable at an opposite end by engagement of latch  50  with hook  52 . An elevation view of hemi-ring  42   a  is shown in FIG. 4A, as taken in the direction of line  4 A- 4 A of FIG. 4.  
         [0023]    The inside diameter D of guide ring  42  is sized to snugly encircle the periphery of tube  29  of sleeve  24  (see FIG. 2). Guide ring  42  has a diametral thickness of T. Guide ring  42  has a vertical thickness t, as shown in FIG. 4A. Vertical thickness t and diametral thickness T are each sufficient to receive and slidingly support collectors  60  in a guide hole  44 ,  46 ,  48 , respectively. Thickness t is preferably on the order of double the outside diameter of collector  60  or greater. Diametral thickness T is preferably about 2-3 times the outside diameter of collector  60 . Ring  42  is formed of a plastic resin, for example nylon, according to the preferred embodiment.  
         [0024]    A plurality of radially aligned holes  44 ,  46  and  48  are formed through guide ring  42  so as to be separated from each other by substantially equal angles α, when ring  42  is closed around circumferential wall  29 . In the case of the illustrated embodiment, guide holes  44 ,  46  and  48  are separated by angles α of 120°. Each guide hole  44 ,  46  and  48  is formed with an enlarged entry on the outer side of guide ring  42  and a slot  44   s  (shown in FIG. 4A) to accommodate a collar portion and pin of collector  60 , as will be described below. Since each of collectors  60   a ,  60   b  and  60   c  are shown in FIG. 3 to be oriented on co-planar radii, only one of collectors  60   a ,  60   b  and  60   c , for example collector  60   a , can be positioned through the center of ring  42  at any one time. With collector  60   a  positioned across throat  30 , alternate collectors  60   b  and  60   c  are retracted to reside mainly outside of ring  42  with their respective inner end caps  78   a  (see FIG. 6) adjacent the inner wall of ring  42 .  
         [0025]    Typical collector  60  is illustrated in exploded perspective view in FIG. 5. Collector  60  is made up of tube  62 , shaft  82 , dies  90   a ,  90   b  and  90   c , and plug  78 . For purposes of description, tube  62  is assumed to have an outer end, shown on the left as illustrated FIG. 5 and an inner end, shown on the right. Outer end and inner end also refers to the radial representation of collectors  60   a ,  60   b  and  60   c  shown assembled to guide ring  42  in FIG. 3. Tube  62  is sized in diameter to slidingly ride in guide hole  44  and collector hole  34 , with a collar  64  located adjacent the outer end of tube  62  sized to snugly engage the enlarged entry of guide hole  44 . A flange  70  is formed at the outer end of tube  62  to control the depth to which tube  62 , including mounted plug  78 , may be inserted into sleeve  24  and serve as a connecting point for rotator  68 . Rotator  68  extends radially outwardly from flange  70  and serves as a control of the angular orientation of tube  62 . Tube  62  is formed with a set of apertures  80   a ,  80   b  and  80   c  which, when tube  62  is appropriately oriented on shaft  82 , are positioned above dies  90   a ,  90   b  and  90   c , respectively. As will be apparent to those skilled in the art, apertures  80  are slightly smaller than respective dies  90  so as to retain dies  90  seated in slot  88  during operation, as described below. Plug  78  is formed with a threaded end to snugly engage a matching thread within the inner end of tube  62 . The outer end of plug  78  is formed with a cap  78   a  that has an end shape that is preferably spherical with a radius r that is parallel to the radius R of throat  30 , as shown most clearly in FIG. 3A. Cap  78   a  is formed larger in diameter than collector holes  34  in sleeve  24 . The spherical radius r of cap  78   a  is smaller than radius R of collar by a space Z between cap  78   a  and tube  29  when tube  62  is fully inserted and flange  70  contacts guide ring  42 . In this configuration, cap  78   a  disturbs the flow of passing mixed powder material to only a minimal degree. The spherical radius r of cap  78   a  is similarly effective in minimizing powder flow disturbance when collector  60  is retracted outwardly as in the case of collectors  60   b  and  60   c  in FIG. 3.  
         [0026]    Shaft  82  is sized to slidingly insert into bore  72  in tube  62  and to extend, when fully inserted, substantially the full length of tube  62 . Shaft  82  is configured with a slot  88  that receives a plurality, for example 3, of dies  90 . As described in the prior patents cited hereinabove, dies  90  each have a cavity  92  that has an internal volume sized to contain a selected quantity, equal to a unit dose of the powder mix. As an alternate choice of the user, dies  90  are adapted to hold a half gelatin capsule to catch the powder mix directly in the capsule, avoiding the need for transfer of the powder samples. Dies are designed to be readily replaced in shaft  82  so that a unit dose of the specific powder mix being processed may be collected. A series of pairs of holes  89  are provided through shaft  82  such that each pair of holes  89  is positioned beneath a respective one of dies  92   a ,  92   b  and  92   c . By inserting a tool (not shown) through each pair of holes  89 , the proximate die  92  is lifted out of shaft  82  enough so that it may be grasped by the fingers or an appropriate tool. The distance between the holes in each pair of holes  89  is greater than the distance between adjacent holes  89  in sequential pairs so that the tool cannot be inserted into holes affecting two adjacent dies. Shaft  82  is further formed with a pin  86  extending radially therefrom and positioned near a handle  84  at the outer end of shaft  82 . Pin  86  is sufficiently long to extend beyond the outer diameter of collar  64  and to engage slot  44   s  in guide ring  42  when assembled. When dies  90  are placed within slot  88  with cavities  92  exposed and oriented to be open upwardly, shaft  82  is placed into bore  72  of tube  62  and pin  86  enters keyway  74  in flange  70 . A slot  66  is formed as a “T,” with its stem parallel to the axis of tube  62  and its cross-bar circumferential thereto. After pin  86  passes through flange  70  into slot  66  in collar  64 , tube  62  is rotated so that pin  86  rides along the cross-bar of slot  66  and cavities  92  are covered by the portion of tube  62  without apertures. The combined length of tube  62  and cap  78   a  is slightly less than the distance from the outside of guide ring  42  to the opposed inside surface of circumferential wall  29  (see FIG. 3A) when assembled.  
         [0027]    The method of operation of the sampling apparatus of the invention is typically as follows. Guide ring  42  is placed around circumferential wall  29  of sleeve  24  and locked in place with guide holes  44  aligned with collector holes  34 . The operator pushes a first tube  62  (see FIG. 3A) into sleeve  24  and threads a mating plug  78  to the inner end thereof. A shaft  82  is prepared for sample collecting by placing a number of dies  90  with cavities  92  exposed into open slot  88 . Shaft  82  is then slidingly inserted into tube  62 . Handle  84  is held still to keep cavities  92  facing up as rotator  68  is turned to close apertures  80 . Additional collectors  60  are assembled to sampler  20  as described above. Each collector  60  is retracted so as to be positioned out of throat  30  to the extent possible. Sleeve  24  is assembled to discharge port  12  on the bottom of blender  10  by threaded fasteners or other means (not shown). Shroud  16  is connected to the bottom of sleeve  24  and its lower open end is placed into receptacle  18 . Valve  14  is opened to allow mixed powdered material to flow from blender  10  through sleeve  24  and into receptacle  18 . At an appropriate time in the process of transfer of the mixed bulk material from blender  10  to receptacle  18 , the operator pushes a handle  84  so as to insert a selected sampler  60  across the width of throat  30 . In so doing, collar  64  (see FIG. 5) enters the enlarged entry portion of guide hole  44 , and pin  86 , extending upward beyond collar  64 , enters slot  44   s . Being engaged in slot  44   s , pin  86  prevents unwanted rotation of shaft  82 , maintaining cavities  92  facing upward. The operator turns rotator  68  clockwise to rotate tube  62  and expose dies  90 , allowing a quantity of bulk mixed material to fill each cavity  92   a ,  92   b  and  92   c . Rotator  68  is turned counterclockwise to close tube  62  over cavities  92   a ,  92   b  and  92   c . The operator pulls handle  84  without rotation so as to retract assembled collector  60  to the extent possible until cap  78   a  contacts the near-inner side of circumferential wall  29 . The operator rotates handle  84  clockwise, to turn both shaft  82  and tube  62 , causing dies  90   a ,  90   b  and  90   c  to be oriented downwardly. The operator holds handle  84  still while rotating rotator  68  further clockwise to move apertures  80   a ,  80   b  and  80   c  of tube  62  to expose dies  92   a ,  92   b  and  92   c , while positioning a container beneath each die to transfer the sample from each die into individual containers for quality testing, as is known. Optionally, the samples obtained may be pressed into tablets prior to testing, which may be done in dies  92 .  
         [0028]    In the alternate process whereby samples of bulk mixed materials are caught in capsules that have been placed in cavities  92 , shaft  82  is kept in its orientation with cavities  92  facing upward as handle  84  is pulled to retract collector  60 . Rotator  68  is turned so that shaft  82  can be withdrawn from tube  62 . A pair of pins of a tool (not shown) is inserted through holes  89  in tube  62  to sequentially lift each die  90  sufficiently so that the operator can remove dies  90  from slot  88  with cavity  92  and the capsule it contains remains upright. The use of a capsule half is preferred in certain circumstances, such as where the finished dosage form is a capsule or where sample compaction is not required.  
         [0029]    To further clarify an objective of the present invention, FIG. 6 shows a diagrammatic representation of a top view of sleeve  24 , with the nine positions indicated from which samples are obtained. Each of the sample positions adjacent the wall of sleeve  24  is marked with an “X” and the three sample positions at the center of sleeve  24  are marked with a single “O.” 
         [0030]    The samples acquired above are from each edge and the center of sleeve  24  along the axis of collector  60   a . Leaving collector  60   a  in its retracted position, the procedure described above is repeated with collector  60   b  and then again with collector  60   c . At the end of this cycle, six samples have been collected from angularly dispersed peripheral locations and three samples from the center of sleeve  24  for comparison of product uniformity or other properties.  
         [0031]    While the present invention is described with respect to specific embodiments thereof, it is recognized that various modifications and variations may be made without departing from the scope and spirit of the invention, which is more clearly and precisely defined by reference to the claims appended hereto.