U.S. patent application number 11/546682 was filed with the patent office on 2007-02-08 for method and apparatus for segregation testing of particulate solids.
This patent application is currently assigned to JENIKE & JOHANSON, INC.. Invention is credited to Dean Lance Brone, Scott A. Clement, Bruno Caspar Hancock, David Bruce Hedden, Michael A. McCall, James K. Prescott, Thomas G. Troxel.
Application Number | 20070028705 11/546682 |
Document ID | / |
Family ID | 37617090 |
Filed Date | 2007-02-08 |
United States Patent
Application |
20070028705 |
Kind Code |
A1 |
Brone; Dean Lance ; et
al. |
February 8, 2007 |
Method and apparatus for segregation testing of particulate
solids
Abstract
A bed of particulate solids is fluidized in a test chamber to
yield multiple test samples for subsequent evaluation of
segregation effects. A controlled stream of gas enters the chamber
in a series of flow rate cycles each progressively increasing to a
maximum rate of gas flow and then decreasing, the maximum rate
increasing for successive cycles. An indicating function is formed
from measurements of corresponding rates of gas flow and pressure
across the bed. Upon termination of the fluidization, multiple
samples are sequentially extracted from a single space at the
bottom of the test chamber.
Inventors: |
Brone; Dean Lance; (Ann
Arbor, MI) ; Clement; Scott A.; (Atascadero, CA)
; Hancock; Bruno Caspar; (North Stonington, CT) ;
Hedden; David Bruce; (Ann Arbor, MI) ; McCall;
Michael A.; (Atascadero, CA) ; Prescott; James
K.; (Shrewsbury, MA) ; Troxel; Thomas G.; (San
Luis Obispo, CA) |
Correspondence
Address: |
LAHIVE & COCKFIELD, LLP
ONE POST OFFICE SQUARE
BOSTON
MA
02109-2127
US
|
Assignee: |
JENIKE & JOHANSON, INC.
Westford
MA
|
Family ID: |
37617090 |
Appl. No.: |
11/546682 |
Filed: |
October 11, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11177615 |
Jul 7, 2005 |
|
|
|
11546682 |
Oct 11, 2006 |
|
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|
Current U.S.
Class: |
73/863.21 |
Current CPC
Class: |
G01N 15/04 20130101 |
Class at
Publication: |
073/863.21 |
International
Class: |
G01N 1/10 20070101
G01N001/10 |
Claims
1. The method of fluidizing a bed of particulate solids for causing
a segregation effect, including the steps of loading the bed into
an upstanding columnar test chamber, causing a stream of fluidizing
gas to flow through an inlet into the bottom of the test chamber
and increasing the rate of flow until the bed is fluidized,
decreasing said rate of flow to zero, and successively extracting a
plurality of samples from a single space at a predetermined
vertical level in the test chamber, whereby the bed falls to refill
said space in response to each said extraction.
2. The method of claim 1, in which each said extraction includes
the application of sufficient gas pressure to the top the chamber
to refill said space.
Description
RELATED APPLICATIONS
[0001] This application is a division of, and claims the benefit
of, U.S. Ser. No. 11/177,615, filed on Jul. 7, 2005, which is
expressly and entirely incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] This invention relates to a method and apparatus useful for
testing powders and other particulate bulk solids with the object
of evaluating their segregation tendencies when fluidized under
industrial conditions.
[0003] To facilitate the industrial processing of powders and other
particulate solids it is common practice to blow air or other gas
into the body of the material. At a sufficient gas flow rate this
results in fluidization, a state in which the solids exhibit
fluid-like properties. Fluidization may also occur unintentionally,
for example during transfer of powder from a blender to a bin, when
air flow through the material may fluidize or partially fluidize
the material.
[0004] However, fluidization is the driving force for a segregation
mechanism that alters the uniformity of the properties of the
solids in different parts of the body, notably the particle size
distribution, but also other properties including for example
particle shape, chemical assay, bulk density, color, and
solubility. Nonuniformity of these properties generally degrades
the quality of the industrial product.
[0005] To obtain useful data on the tendency of a particular body
of solids to undergo significant segregation when fluidized under
industrial conditions, simulation test practices have been devised.
These simulate the industrial conditions using a quantity of the
solids in a test chamber, employing an accurately repeatable
fluidization test procedure. At the conclusion of a test, multiple
samples are taken from different parts of the test chamber and
subjected to separate assays and analyses of the properties of
interest. These results for a new material may be compared with the
results for other solids having known segregation properties when
similarly tested in the same apparatus and with the same fluidizing
test procedure. This comparison provides an indication of potential
of the new material to segregate by fluidization in a given
industrial application.
[0006] The tester can also be used simply to determine the
suitability of a new material to fluidize in an industrial
application, irrespective of segregation potential or concerns.
[0007] The objects of the present invention are directed to
improved test apparatus and procedures. The resulting samples may
be evaluated using presently existing or future techniques.
[0008] A standard practice for measuring fluidization segregation
tendencies of powders is described by ASTM International under
Designation D6941-03. A suitable apparatus for the purpose is
described in U.S. Pat. No. 6,487,921. A vertical columnar test
chamber is filled with a bed of the solids, subjected to a
fluidization procedure and adapted for removal of samples from
several vertical levels of the chamber after completion of the
procedure. During the procedure air or other gas is forced into the
bottom of the chamber under pressure, and the gas flow rate is
measured and increased to a "high flow rate" at which the bed is
observed to be fluidized. The flow rate is then reduced to a "low
flow rate" at which a minimum level of fluidization is noted, then
held at or near the low flow rate for a predetermined "hold time,"
and finally reduced to zero. The fluidization of the bed allows or
may cause segregation of the material. For example, in powders of
mixed particle sizes, segregation causes the lighter, finer
particles to increase in concentration towards the top, and the
coarser, heavier particles to increase in concentration at the
bottom.
[0009] In practice, the existing standard practice and its
variations have a number of drawbacks. For example, it is
frequently necessary to run two tests for each material, a first or
characterizing test to determine the appropriate high and low flow
rates, and a second or actual test to produce the samples for
analysis.
[0010] The existing test procedure is influenced by subjective
factors varying with the individual performing the test, including
observation of the material behavior such as formation of bubbles
or turbulence at various levels in the material and expansion or
lifting of the bed of material, and control of the rate of change
in the flow rate. Thus different persons can produce different test
conditions and cause inaccurate, nonrepeatable test results.
[0011] The existing standard test procedure typically yields
individual samples of substantial volume which, although suitable
for certain types of analysis, are often too large for some other
common analytical methods. As a result, time consuming
sub-sampling, sample splitting or riffling procedures are needed to
obtain validly representative smaller quantities for analysis.
Sub-sampling can also lead to errors and material loss.
[0012] The existing standard test has proven ineffective for
certain materials that do not fluidize easily using the prescribed
time and flow rate profile.
[0013] The existing standard test procedure typically consumes as
much as 85 ml of material not only for the first or characterizing
test, but also another 85 ml of material for the second or actual
test. This is often more material than the quantity available
during early stages of development of a particulate solid material,
for example a pharmaceutical formulation. Attempts to reduce the
size of the current test chamber, while employing the same
fluidization profile described in the ASTM method, are ineffective
for cohesive materials, since the wall effects, i.e. the total
friction along the walls of the chamber relative to the weight of
the material, are more pronounced.
BRIEF SUMMARY OF THE INVENTION
[0014] With the object of overcoming the above and other drawbacks,
the features of this invention include a flow rate cycling or
ramp-up method of controlling the gas flow rate for the achievement
of fluidization in the test chamber. This method permits the
fluidization of materials that do not fluidize easily, and reduces
the likelihood of channeling of the gas, cohesive effects, and
entraining of particles in the gas stream.
[0015] According to another feature of the invention, the flow rate
cycling method is employed in conjunction with the monitoring and
recording of the gas pressure at the inlet to the test chamber.
This permits observation of the functional relationship between the
gas flow rate and the inlet pressure as an indication of
fluidization conditions in the test material.
[0016] In particular, a preliminary test of the apparatus may be
conducted with the test chamber empty to measure and record the
background pressure drop measured at the inlet to the chamber as a
function of the rate of gas flow. This pressure drop is the result
of friction and turbulence effects created within the gas flow
passages, apart from the test material. In the subsequent tests
with material in the test chamber, the appropriate background
pressure drop may be subtracted from the measured pressure to yield
the net pressure drop through and due to the bed of material under
test.
[0017] An indicating function is produced and may be plotted to
show values of the net pressure drop as a function of the gas flow
rate. Observation of this function permits less subjective
evaluation of the state of fluidization and subsequent control of
the test, as hereinafter more particularly described.
[0018] A feature of the invention is an improved method of
extracting samples from the test chamber. The samples at a
plurality of vertical levels are sequentially removed from the
bottom of the chamber. The samples are of small size as compared,
for example, to those obtained with the apparatus of U.S. Pat. No.
6,487,921, and are preferably equal in volume to that required for
assays or other methods of analysis. This eliminates the need to
sub-sample or subdivide the sample by riffling, both of which take
additional time and can result in errors and material losses.
[0019] Another feature of the invention is that it enables the use
of a test chamber of smaller size than the chamber used in the
existing apparatus, requiring as little as 19 ml per test, for
example, while being effective even for more cohesive materials.
This reduces cost and material waste, and may allow testing in some
cases where larger samples cannot be provided.
[0020] As a consequence of the foregoing and other features
hereinafter described, the invention uses less test material,
provides increased sensitivity to and resolution of segregation
that has occurred, is more likely to reach full fluidization of the
test material, reduces the subjectivity of the observations and
control of test conditions, and produces samples of a size that can
be used directly in common assay methods.
BRIEF DESCRIPTION OF THE DRAWING
[0021] FIG. 1 is a view in perspective of the tester.
[0022] FIG. 2 is a schematic drawing of the testing apparatus for
purposes of explanation.
[0023] FIG. 3 is a plot showing the background pressure drop stored
in a memory as a function of the rate of gas flow.
[0024] FIG. 4 is a plot or profile of the gas flow rate against
time during a test according to the invention, illustrating the
flow rate cycling and ramp-up method of the invention.
[0025] FIG. 5 is a plot of the response of the net pressure to the
cycling flow rate produced during an illustrative test of a
particular material, idealized for purposes of explanation.
[0026] FIG. 6 shows the particle size and chemical assay results of
a test on an example of material.
[0027] FIG. 7 is an elevation in section of the tester taken on
line 7-7 of FIG. 1 showing the loading of a fill capsule of test
material.
[0028] FIG. 8 is an elevation similar to FIG. 7 showing a loaded
bed of the material in position for running a test.
[0029] FIG. 9 is an elevation similar to FIG. 7 showing the tester
in position to abort a test and discharge the test column.
[0030] FIG. 10 is an elevation in section of the tester taken on
line 10-10 of FIG. 1 showing details of the discharge of tested
material to the sample vials.
[0031] FIG. 11 is a view in plan of the tester taken on line 11-11
of FIG. 1 and corresponding to FIG. 10.
DETAILED DESCRIPTION
[0032] FIG. 1 is a general view of the preferred form of tester and
FIG. 2 schematically shows the tester connected with added
components to form the complete testing apparatus.
[0033] A test column indicated generally at 10 forms a vertical
cylindrical test chamber 12, a conical expansion section 14 useful
for breaking up conveyed plugs of material, a vertical section 16,
an elutriation chamber 18 for separation of gas from the material,
a dust filter 20, and a cap 21.
[0034] A fluidizing gas tube 22 is connected to a diffuser 24 of
sintered metal or the like located at the bottom of the chamber 12
for injecting gas into the material uniformly over the cross
sectional area "A" of the chamber. A sampling disk 26 is located
preferably immediately above the diffuser with a recess 28 therein
removably located below the chamber 12 and containing the lowermost
layer of a bed 30 of test material such as powder or the like. The
disk 26 has multiple recesses arranged for sequential movement into
the space occupied by the recess 28 for successively removing
layers of the material in the bed after completion of a test, as
hereinafter described in connection with FIGS. 10 and 11.
[0035] Typically, the bed 30 is filled to a level 32, allowing
additional space 34 for bed expansion as hereinafter described. The
diverging section 14 is provided for plug breaking as needed in
conjunction with the testing of certain materials.
[0036] A flow controller 35 has a connection 36 to a source of
fluidizing gas under pressure (not shown), for example air,
nitrogen or another gas similar to that employed under expected
industrial conditions for the material under test. The controller
35 may be a conventional device for indicating and controlling the
rate of gas flow "Q," namely the volume rate of gas flow in the
inlet tube 22.
[0037] A pressure sensor 38 is connected to the diffuser 24 by a
tube 39 and indicates the pressure "P" at the inlet to the diffuser
24.
[0038] An indicating function generator 40 is provided with an
input connection 42 for receiving a value Q/A, "A" being the cross
sectional area of the bed 30. A second input 44 receives a value
P-P.sub.b, whereby the generator 40 produces a function profile of
its inputs for observation of a test. FIG. 5 illustrates such
functions.
[0039] The quantity "P.sub.b" is a background pressure drop and is
a function of "Q" as determined in a preliminary test run as next
described. This function is retained in a memory 46 having means to
subtract the appropriate background pressure drop from each
measured level of "P" during a test.
[0040] To determine the background pressure drop function, a
preliminary test run is conducted with no material in the test
chamber. The flow rate is increased from zero to the maximum value
expected during a test, and corresponding levels of P.sub.b are
recorded in the memory 46, idealized levels being represented in
FIG. 3 by a straight line 47.
[0041] The test chamber is then loaded with a bed 30 of test
material up to the level 32 allowing space for expansion. In the
method of this invention, the controller 35 is adapted to control
the flow rate Q/A in cycles 50 as shown in FIG. 4, each cycle being
of controllable duration and comprising a ramp-up subperiod to a
maximum value, a hold subperiod at the maximum value and a
ramp-down subperiod to zero. The ramp-up, hold and ramp-down
subperiods are of controllable duration. Pauses of controllable
duration are preferably provided between successive cycles. The
duration of each of the sub-periods in seconds as shown in FIG. 3
is a presently preferred value, and in practice it is selected by
the user.
[0042] The maximum flow rate increases in magnitude from each cycle
to the next succeeding cycle by the same predetermined increment or
a changed increment determined by observation during the test.
[0043] The initial cycle 50.sub.a reaches a maximum flow rate less
than that which causes fluidization of the particular material.
[0044] As shown in FIG. 5, the corresponding plot produced in the
cycle 50.sub.a by the generator 40 is represented by a function
F.sub.a showing that the net pressure rises linearly with respect
to the flow rate, and descends linearly to zero on the same line,
thus being "path independent."
[0045] A second cycle 50.sub.b generates a second linear function
F.sub.b indicating that the maximum flow rate in this cycle has not
yet achieved fluidization of the material.
[0046] A third cycle 50.sub.c reaches a flow rate exceeding that
which initiates fluidization of the material. As shown by the
resulting curve F.sub.c, expansion of the fluidized bed begins and
causes decreasing bulk density with a consequent drop in the net
pressure across the bed. The net pressure continues to drop during
the hold subperiod and until it reaches a value P.sub.d below which
the decreasing flow rate becomes insufficient to sustain
fluidization, and the net pressure then tends to follow a more
nearly linear response to the end of the cycle as the flow rate
ramps down to zero.
[0047] During the cycle 50.sub.d a function F.sub.d is generated,
indicating that the material reaches fluidization at a lower net
pressure than that reached during the cycle 50.sub.c. At a certain
flow rate below the maximum rate in this cycle, the net pressure
reaches the level P.sub.d and remains constant thereafter with
increasing flow rate.
[0048] During a cycle 50.sub.e a curve F.sub.e is generated,
indicating that the material becomes and remains fluidized as soon
as the net pressure reaches the level P.sub.d, and the net pressure
does not increase for greater values of the flow rate.
[0049] Observation of the curves generated by successive cycles as
shown in FIG. 5 permits a determination of the duration of the test
that is accurately repeatable for successive tests of the material.
For example, a test may continue until the occurrence of three
points 52 at the level P.sub.d in cycles 50.sub.d, 50.sub.e and
50.sub.f. Thereupon, the test may be concluded by a ramp-down of
the flow rate to zero in a final cycle 50.sub.f in a predetermined
subperiod 54.
[0050] It will be understood that the foregoing explanation of a
representative test of material in connection with FIGS. 4 and 5
applies to a typical material that is relatively easy to fluidize
without the formation of plugs of material or channeling, that is,
the formation of channels of gas flow through the bed as opposed to
uniform permeation of gas through the full cross section of the
test chamber. However, the invention has distinct advantages for
less easily fluidized materials.
[0051] Initially, with small flow rates, the material bed remains
stationary, and the net pressure drop through the bed tends to
remain more or less linear with increasing flow rate. Once the flow
rate is sufficiently high to cause the force of the air flow
upwards to balance the downward force of gravity, the material
becomes fluidized. If the flow rate is increased above this value,
it results either in expanding the fluidized bed and decreasing the
bulk density, and/or the formation of bubbles in the bed. In
general, a dense bed of material will exhibit a pressure drop more
or less linear with increasing gas flow rates up to the point where
it becomes fluidized, expands and is loosened, whereupon the
pressure drop will decrease with increasing flow rate.
[0052] If the material is somewhat cohesive, it may tend to rise
initially as a plug. Reducing or stopping air flow, as occurs in
the practice of this invention, provides an opportunity for the
plug to collapse.
[0053] In the case of a plug forming, the pressure drop through the
bed might exceed that calculated on the basis of the weight of
material alone, as friction against the walls provides additional
resistance. Once the plug breaks, subsequent refluidization will
follow a different path.
[0054] Once fluidized, the material may begin to bubble. Slow,
erratic bubbles may be responsible for scatter in the data forming
the curves similar to FIG. 5, for example as bubbles get large
enough to overcome cohesion.
[0055] On the other hand, if the material is sufficiently cohesive,
it may not fluidize well, and the air or other gas might blow a
channel through the material. Additional air flow through the
diffuser 24 will not flow through the portion of the bed that is
static, but instead will flow through the channel. In this case,
the pressure drop obtained does not reach that based on the weight
of material.
[0056] Similarly, even once material is fluidized, a flow channel
may form, resulting in the collapse of a portion of the bed.
[0057] If there is a range of particle sizes within the material,
it will not exhibit a distinct flow rate of initial fluidization.
Instead, the finer portion might fluidize while the coarser portion
remains stationary, in which case segregation is likely to have
occurred. This results in a curved function instead of those shown
in FIG. 5.
[0058] It is possible that the material is one that segregates
slightly at low flow rates, with segregation becoming more intense
at higher flow rates. This produces curves having corresponding
characteristics.
[0059] From the foregoing description, it will be evident that an
advantage of the invention resides in the ability to reach
fluidization of the material. Simply increasing the flow rate from
zero can result in channeling of the material. Problems arise with
prior test methods in which this is overcome by increasing the flow
rate to a very high value, then decreasing it back to a region of
interest, in that they are not always effective, require higher
flow rates than the test equipment can handle, and may cause
significant material to be conveyed out of the test chamber.
Vibration or impact to the chamber may pack the non-fluidized
material further, making channeling more likely, and may induce
other mechanisms of segregation.
[0060] The present invention avoids the necessity of increasing the
flow rates to values substantially above those required to achieve
fluidization.
[0061] The present invention permits the design of test equipment
for smaller volumes of sample material than those required for
previous testers. With smaller test volumes, the invention provides
a means for improved initiation of fluidization of the bed. The
pulsing of air flow as described, with increasing peak flow rates
for successive pulses, is an effective way of overcoming cohesion
and channeling of the material.
[0062] The invention also uniquely addresses the critical goal of
obtaining fluidization of the material at the lowest possible flow
rate, in order to avoid elutriation of fines in the material, thus
more closely mimicking the state of aeration of material
experienced as a result of material transfer in production scale
equipment. Observing curves corresponding to those of FIG. 5 for
real time observation, test personnel learn for each pulse whether
the material became fluidized, and if so, to some extent, whether
segregation has fully developed. This allows the observer, or
computational means, to be employed for minimally exceeding the
flow rate necessary to achieve fluidization during a given material
test.
EXAMPLE
[0063] A test chamber 16 mm in diameter was filled with a
particulate material to a level of 95 mm. A five micron sintered
metal diffuser disk 24 was fitted at the base of the chamber. A
"target flow rate" was estimated, by prior test work and
theoretical calculations, to be slightly above the lowest level
sufficient to sustain fluidization. This target rate was divided by
7, the estimated number of cycles to complete the test, thus
determining the increment of velocity Q/A to be added to each
successive cycle.
[0064] Upon completion of the test, sixteen 1.2 mil samples, each
of which was located at a distinct level or position during the
test, were successively recovered from the chamber. Even numbered
samples were assayed for percent of intent and odd numbered samples
were measured to determine particle size distribution. The results
are illustrated in FIG. 6, and show that assay and particle size
variations are pronounced, indicating possible segregation problems
with this material.
[0065] FIGS. 7 to 11 illustrate details of the tester for
practicing the test method of this invention. The sampling disk 26
permits removal of thin slices of the material from the bottom of
the bed 30 each time the disk is rotated to present a succeeding
recess 28 in the disk. As each recess in the disk is removed from
the bed, the bed falls by gravity as a plug, filling the next
recess. In some cases where the material is very cohesive, gas
pressure may be applied to the top of the test chamber to ensure
that each recess 28 is filled. In this way, the top-to-bottom
composition of the bed is maintained as samples are collected.
Generally, with a bed formed of coarse and fine particles, the
initial samples are the coarsest and become progressively finer as
the sampling disk rotates. In practice, about 16 samples may be
collected, but the number of samples is variable according to
choice. Once the samples are collected for each test, they can be
analyzed by any known techniques of assay or other method of
evaluation such as NIR ("Near-Infrared"), HPLC ("High Pressure
Liquid Chromatography"), and AA ("Atomic Absorption"), particle
size methods, microscopy, color, or bulk density.
[0066] The tester has a base assembly 60 which supports the test
column 10 and a carrousel assembly 62. The base assembly supports a
vertical test column shaft 64 comprising an outer clamp shaft 66
and an inner clamp shaft 68. A molded plastic bottom section 70 is
slidably received over the shaft 64 and rests in a fixed position
on the base 60. The sampling disk 26 is slidably received over the
shaft 64 and rests on the bottom section 70. A central section 72,
preferably of clear molded plastic with an elongate hole from top
to bottom forming the test chamber 12, is slidably received over
the shaft 64 and rests on the sampling disk 26. A top section 74 of
molded plastic is slidably received over the shaft 64 and rests on
the central section 72.
[0067] An outer shaft latch 76 fits within a recess in the top
surface of the central section 72 and slides into a peripheral
groove on the outer clamp shaft, whereby a downward force on the
latter relative to the base 60 securely clamps together the central
section 72, the sampling disk 26 and the bottom section 70.
Similarly, an inner shaft latch 78 fits within a recess in the top
surface of the top section 74 and slides into a peripheral groove
on the inner clamp shaft 68, whereby a downward force on the latter
relative to the base securely clamps together the top section 74,
the central section 72, the sampling disk 26 and the bottom section
70.
[0068] A clamping mechanism 80 is mounted in the base assembly 60
and provided with a clamping handle 82 (FIGS. 1 and 11) extending
through an opening in the base and permitting movement of the
handle to positions 82a, 82b and 82c. With the handle in position
82a the mechanism 80 applies downward force to the inner shaft 68
relative to the base, thereby clamping the top, central and bottom
sections 74, 72 and 70 and the sampling disk 26 firmly together.
With the handle in the position 82b the mechanism 80 exerts a
downward force on the outer shaft but not the inner shaft, whereby
the shaft latch 76 clamps together the central and bottom sections
72 and 70 with the sampling disk 26, leaving the top section 74
free to be rotated manually. With the handle in the position 82c
neither the outer nor the inner shaft is subjected to a downward
force, thereby allowing the central and top sections as well as the
sampling disk 26 to be manually rotated as desired.
[0069] The sampling disk 26 has notches 84 (FIG. 11) spaced 90
degrees around its periphery and fits within a ring 86 bearing a
ratchet pawl 88 with a handle 90 for advancing the sampling disk in
successive movements of 90 degrees.
[0070] The carrousel 62 is provided with recesses for receiving a
number of vials 92 (FIG. 10). A suitable mechanism is provided for
manually advancing the carrousel to present successive vials in a
position 94 (FIG. 11) for receiving the samples. A suitable handle
96 is provided for clamping the carrousel to the base 60 and for
carrying the carrousel with filled vials to a separate location for
assays or other measurements.
[0071] Material to be tested is initially loaded into a fill module
98 when held in a position inverted from that shown in FIGS. 7 to
9. An inlet valve body 100 having a stopcock 102 is then attached
to the top of the module 98. The stopcock has a thru hole 104. With
the valve in the closed position as shown, the module and valve
subassembly can be inserted into an aperture in the top section 74
diametrically opposed to an aperture for receiving the elutriation
chamber 18.
[0072] FIG. 7 shows the test column 10 in position for the start of
a test with the fill module and inlet valve body fitted on the top
section 74, and with the test chamber 12 aligned with the
elutriation chamber 18, a recess 28 in the sampling disk 26 and the
diffuser 24.
[0073] With the clamping handle 82 moved to the position 82b (FIG.
11) the top section 74 is rotated 180 degrees into alignment with
the test chamber 12, and the stopcock is turned to permit the test
material to fall into the chamber 12. The top section is then
rotated to its original position as shown in FIG. 8. The clamping
handle 82 is then moved to the position 82a. The test procedure may
then be commenced as described above.
[0074] When the test is completed the clamping handle 82 is moved
to the position 82c, thereby removing pressure from the sampling
disk and permitting it to be rotated sequentially while the bottom,
central and top sections of the test column remain fixed, to remove
successive slices of the tested material from the chamber 12,
depositing them sequentially in the sample vials 92.
[0075] If it is desired to abort a test procedure before
completion, with the clamping handle in the position 82c the
central section 72 can be manually rotated to a position
illustrated in FIG. 9. In this position the chamber 12 is aligned
with an aperture 28 in the sampling disk and a hole 106 in the
bottom section 70 opening into a recess in the bottom section in
which a receptacle 108 is placed.
* * * * *