Abstract:
Instruments for measuring the gas flow permeability of a fiber sample, particularly a cotton fiber sample; and apparatus and methods employing multiple volumetric compressions to acquire data products for determining “micronaire,” “maturity” and “fineness” of the fiber sample. A gas flow permeability testing instrument includes sensors in a gas flow stream enabling the determination of fiber mass delivered to a testing chamber, and a computer outputting a control signal to terminate delivery of fibers to the testing chamber when a predetermined mass set point is reached. A multiple compression fiber gas flow permeability testing device includes a testing chamber into which a fiber sample of known mass is delivered. A movable chamber wall is driven in a substantially continuous manner so as to compress the fiber sample, while a gas flow system determines permeability. A data processing device acquires permeability and chamber wall position (testing chamber volume) data at a sampling rate while the wall is moving.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This is a continuation of U.S. patent application Ser. No. 09/663,503, filed Sep. 15, 2000, which in turn claims the benefit of U.S. Provisional Patent Applications Ser. No. 60/154,527, filed Sep. 16, 1999; Ser. No. 60/182,731, filed Feb. 15, 2000; and Ser. No. 60/221,104, filed Jul. 27, 2000. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    The invention relates generally to fiber quality measurements for cotton classing and, more particularly, to air flow permeability instrument measurements.  
           [0003]    Cotton standards are supported by the United States Department of Agriculture (USDA) through its Agricultural Marketing Service (AMS). Cotton standards, and the corresponding classing of cotton, are of great importance in determining the market value of a particular bale of cotton, as well as determining suitability of a particular bale of cotton from a gin for subsequent processing at a particular mill in view of the products and processes of that mill. AMS is responsible for preparing and maintaining such cotton standards and does so in its Standards Section located in Memphis, Tenn.  
           [0004]    In 1923, the United States and nine European countries entered into the Universal Cotton Standards Agreement. From that time, up until approximately 1965, USDA/AMS cotton classing “measurements” based on the Universal Standards were made entirely by humans. The human measurements included “grade,” “extraneous matter” (such as bark and grass), “preparation” (which relates to smoothness of the sample) and “staple length” (long fiber content). Instrument based cotton classing was introduced in 1965, beginning with micronaire, an air flow permeability measurement, followed in 1980 by High Volume Instruments (HVI), which added measurements of length and strength. HVIs currently measure the fiber qualities of Micronaire, Length, Strength, Color and Trash.  
           [0005]    Since approximately 1950, various forms of the “Micronaire” air flow permeability measurement have been widely used in the classification of cotton. The permeability measurement was originally calibrated in terms of linear density or fineness, with dimensions in the United States of micrograms per inch, with a typical and good value being 4 μg/in (10 μg/cm), and with ranges in value from as low as 2 μg/in (5 μg/cm) to as high as 7 μg/in (18 μg/cm). Most varieties, when “normally matured,” have values in the range of 3 μg/in (7.6 μg/cm) to 5 μg/in (12.7 μg/cm). It was later found that this fineness interpretation was incorrect, since the calibration between permeability and true weight fineness could not be robustly adjusted to fit most cotton types, so the fineness dimensions were dropped. But since the measurement was found to be useful for processing, particularly for “wastiness” and for other processing problems, the measurement was standardized and its use grew. Micronaire became the first non human based measurement to enter the trading of cotton, widely, and was introduced officially into AMS classing in 1965.  
           [0006]    In the standardization of this simple measurement, a known (by a precision balance) sample mass is compressed into a known, fixed volume, air is forced through this compressed plug, and the resulting air flow permeability, a ratio of flow rate to pressure differential (usually to the one half power), is calibrated in terms of “accepted” values of micronaire provided by the USDA. Thus the measurement is calibrated on cotton at a fixed bulk density of the plug or, alternatively stated, at a fixed compression volume for the fixed and known mass. Nearly 50 years of experience with this measurement substantiate its usefulness but, equally strongly, its shortcomings. Other apparatus has been offered which provides permeabilities at two compressions of the same sample mass. From these data, additional fiber properties, including Maturity and Fineness, can be inferred, based on calibrations for these fiber qualities. These “double compression” testers were manufactured by Shirley Developments, Manchester, England and Spinlab, Knoxville, Tenn., and called the Fineness and Maturity Tester and the Arealometer, respectively. These instruments are not widely used because the calibrations are not sufficiently robust and the results are very operator and sample state sensitive. The Arealometer is no longer manufactured.  
           [0007]    Further adding to the difficulties for these measurements, definitions for Maturity and Fineness are not widely agreed. The better or “more unbiased” of the many definitions in use relate to the fiber cross sectional shape and to the fiber cross sectional area, respectively. Such data can only be produced by image analysis of carefully prepared fiber cross sections that are too slow for commercial use, even with modern image analysis methods.  
         SUMMARY OF THE INVENTION  
         [0008]    The better basic definitions referred to above require far more rigorous permeability data; permeabilities at tens of compressions are needed, not two. Prior art apparatus is completely inapplicable for extension to acquire permeability readings from tens of compressions. For clarity, we note that the conventional term “compression” means, more rigorously, bulk density, mass of fiber per unit volume, grams/cm 3 .  
           [0009]    It is therefore seen to be desirable to provide continuous or nearly continuous measurements of rigorous air flow permeabilities, so that robust and useful measurements of cotton Micronaire, Maturity and Fineness can be inferred. It is further seen to be desirable to enable more rigorous calibrations, in terms of basic cross sectional data.  
           [0010]    Embodiments of the invention employ sensors to determine when a predetermined mass of fibers has been delivered to a testing chamber, allowing for automated operation without requiring an operator to guess sample weight. The testing chamber has a movable wall, and an actuator drives the movable wall so as to compress the fiber sample in a substantially continuous manner. A transducer measures the position of the movable wall, and a data processing device acquires gas flow rate through the chamber, pressure difference, and position data at a sampling rate while the wall is moving. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]    [0011]FIG. 1 is an overview of a machine embodying the invention, which machine measures cotton samples to produce multiple data products, including images, and additionally internally and ultra-rapidly conditions samples;  
         [0012]    [0012]FIG. 2 shows the turntable in its loading/measurement position;  
         [0013]    [0013]FIG. 3 is a side view;  
         [0014]    [0014]FIG. 4 is an enlarged view of a portion of the FIG. 1 machine, showing the MMF module in side elevation;  
         [0015]    [0015]FIG. 5 shows the turntable in its transfer/eject position;  
         [0016]    [0016]FIG. 6 is a partial cross section taken on line  6 - 6  of FIG. 3;  
         [0017]    [0017]FIG. 7 is a micronaire performance graph.  
     
    
     DETAILED DESCRIPTION  
       [0018]    Referring first to FIG. 1, the invention is embodied in a stand-alone instrument  100  which measures cotton samples to produce multiple data products, including images, and additionally internally and ultra-rapidly conditions samples. Instrument  100  is a robust, stand-alone platform upon which fiber quality measurement modules are placed to effect generation of multiple data products. By including internal, ultra-rapid sample conditioning, the instrument  100  eliminates the need for expensive conditioned laboratory space. The machine  100  thus does the work of several other instruments and an expensive laboratory air conditioning system, and does that work in the challenging ginning environment.  
       System Overview  
       [0019]    Operator  101  in FIG. 1 selects a “Classer&#39;s Sample” having an estimated weight of approximately 15 grams of sample  102 . Such a 15-gram sample is typically 5 inches (12.7 cm) wide×8 inches (20.32 cm) long×1 inch (2.54 cm) thick, when uncompressed. The operator “swipes” permanent bale identification (PBI) tag  104  through bar code reader  106 , and prepares and introduces sample  102  into recessed conditioning/test chamber  110  of “stable table” top  111 , when pressure/distribution plate  202  is retracted. The operator  101  then initiates automatic conditioning/testing by causing pressure/distribution plate  202  to move over sample  102  in the recessed conditioning/testing chamber  110 , compressing the sample to a thickness of less than 3 mm. Directed by a process control computer  112 , the machine  100  then automatically effects “Ultra-Rapid Conditioning” in module  200 , and additionally effects testing of the sample  102  for Color and Trash in module  300 . (Operator  101  can monitor and control the progress of conditioning/testing, and of all other operations, as well as examine the data products produced, stored, and communicated by system  100  via computer  112  and touch-screen display  113 .)  
         [0020]    Conditioned gas for conditioning sample  102  in conditioning/testing chamber  110  and for transporting and processing sample  102  in subsequent steps is provided by air conditioning module  114 . Air conditioning module  114  provides a conditioned gas flow  116  having controlled environmental parameters such as Relative Humidity of 65%, dry bulb Temperature of 70° F. (21° C.), and flow rates of 200 CFM (5.7 m 3 /min). Conditioned gas flow  116  is conducted to the entrance  117  for both the individualizer  120  flow  122  and for the sample conditioning module  200 . In a variation, gas flow  116  is split into two components, one having the fixed, standard parameters just described and a second having variable humidity, temperature, flow rate and pressure and which variable parameters are automatically controlled by a separate controller within air conditioner  114 , and which parameter values are determined in accordance with optimally conditioning sample  102  within conditioning/testing chamber  110 .  
         [0021]    In overview, sample  102 , having been manually or automatically placed in recessed conditioning/testing chamber  110 , with the pressure/distribution plate assembly  202  over it, is ultra-rapidly “conditioned” from above window  204  and “tested” for Color and Trash below it. Sample  102  may also be tested for moisture content in chamber  110 , according to which data air conditioning module  114  is caused to optimally condition sample  102  under control of computer  112 .  
         [0022]    At the completion of the conditioning/testing cycle, pressure/distribution cover  202  (or pressure plate (not shown) in the event Ultra-Rapid Conditioning is not employed) is opened. The cover  202  may be opened manually, or automatically upon receipt of a signal from computer  112 . Sample  102 , which is now conditioned for further processing and testing, is automatically or manually moved onto belt  118  for quick transport to an individualizer  120 , which thoroughly opens, i.e., “individualizes,” sample  102  into its various constituent entities, fibers, neps, trash, seed coat fragments, sticky points, microdust, and the like. A suitable individualizer is disclosed in Shofner et al U.S. Pat. No. 5,890,264. An alternative is for individualizer  120  to also clean sample  102  by removing trash, microdust and other foreign matter. However, in the disclosed embodiment almost all of the individualized entities are transported in the same transport flow stream.  
         [0023]    This processing by individualizer  120  causes the thoroughly individualized entities to be entrained in or transported by about 120 CFM (3.4 m 3 /min) of conditioned air flow  122  such that the fiber and other entity concentrations transported by the gas flow at the output  126  of individualizer  120  are very low. Accordingly, the Nep content of thus individualized sample  102  is measured with a nep sensor  124  which advantageously is built into the individualizer  120 . A suitable nep sensor  124  is as disclosed in Shofner et al U.S. Pat. No. 5,929,460.  
         [0024]    Sample  102 , whose mass was guessed by operator  101  at approximately 15 grams, is at the output  126  of individualizer  120  in a highly opened, individualized state that simulates the state of fiber in important textile processing machines, especially carding. Accordingly, the state of the fiber is ideal for testing the individual fibers and other entities in the gas flow  122 . One such test is the Nep test made by nep sensor  124 . Other tests are Micronaire-Maturity-Fineness (MMF), effected by module  400 . For Neps and for MMF, it is required that the sample weight be known, not guessed, and sample masses of nominally ten grams are commonly used for both tests. The sample mass can be determined prior to or after the testing using known analytical balance technologies. Post testing weighing can be automated.  
         [0025]    The system aspects of the disclosed embodiment can be summarized:  
         [0026]    1. Common flow;  
         [0027]    2. Optimal sequence for sample tests, from surface measurement of Color and Trash to volume or weight measurements of Neps and Micronaire based on guessed weight or on precise weight;  
         [0028]    3. Ideal sample state for simulations of actual processing (e.g., cleanability, processability, spinnability); and  
         [0029]    4. Automatic except for selecting and introducing classer&#39;s sample, thus eliminating operator effort and errors. System and methods can be extended to complete automation.  
       Electro-Optical Sample Weight Control  
       [0030]    Included are a volumetric flow rate sensor  402  and an electro-optional light scattering or extinction sensor  404 . Volumetric flow rate sensors  402  are well known, including sensor systems  402  that communicate bi directionally with computer  112  (RS 232).  
         [0031]    The output of electro-optical sensor  404  is proportional to the mass concentration of entities in the gas stream at the output of individualizer  120 . Such mass concentration sensors are available from PPM, Inc, Knoxville, Tenn. Note that the volumetric flow rate  415  measured by sensor  402  is preferably (but not necessarily) substantially identical with the flow  122  at the input to individualizer  120 , which is also the same as that drawn in at inlet  117 , which inflow is a major component of conditioned flow  116  from conditioning apparatus  114 . The commonality of the sample  102  conditioning and transport flow, from introduction onto belt  118  to disposal into lint box  130 , is one of the major system aspects of the disclosed embodiment.  
         [0032]    Since the volumetric flow, m 3 /sec, via sensor  402 , is known, and since sensor  404  measures mass concentration, g/m 3 , it follows that the product is a measure of the mass delivery rate, dM e /dt grams/sec. The subscript e indicates that the mass is measured electro-optically. Computer  112  records, at high scan rates of order 100/sec, the outputs of volumetric flow rate sensor  402  and electro-optical mass concentration sensor  404 , computes their product, and accumulates the mass delivery rate contributions until a mass set point M e SP, grams, is reached. (This will be recognized as a discrete summation whose limit is the integral of the mass concentration×flow rate product with respect to time.) When this set point is reached, at least two control actions are taken by computer  112 : the nep counts and size distribution accumulated during the processing of M e  grams of fiber are stored in a register for later computations, and the fiber is diverted within MMF module  400  to lint box  130 . Computer  112  may also speed up the feed rate for the remaining portion of sample  102  since it is of no further use in this context, as a third action.  
         [0033]    Deriving a precisely measured sample mass is another of the major system aspects of the disclosed embodiment.  
         [0034]    The nep data product is thus neps per gram, which can be based on either the electro-optical value M e SP just described or a post-determined gravimetric value M g  described in greater detail below in the context of the MMF module  400 . Nep size distribution is also provided. Importantly, the sample mass introduced into the MMF module  400  is known, as M e SP, and is far more precise than operator guesswork, having Coefficient of Variation CV typically well under 10%. For some applications, the precision of an electronic balance, gravimetric determination, known as M g , including the automated method following the MMF measurement step disclosed below, is not necessary.  
         [0035]    The nominally 10 gram portion of sample  102  M e SP is then tested in MMF module  400 . The remaining portion of the 15 gram estimate has been diverted to lint box  130 . After testing, the nominal 10 gram portion is released onto balance  436 , where mass M g  is gravimetrically measured and reported to computer  112 . Mass M g  can thus be used for all data products requiring precise mass, such as neps/gram, or to adjust MMF readings to the standard 10 gram values. It is very important to note, as another system aspect, that the operator  101  has been freed from the time consuming and error prone task of pre-weighing samples  102 .  
         [0036]    When the balance  436  acquires the sample mass and computer  112  accepts it, computer  112  causes the sample on balance pan  412  to be drawn into suction tube  450  by opening door  452  (FIG. 3) which finally delivers this portion of the sample to lint box  130  via pipe  453 . The flow  132  into lint box  130  is the same, preferably, as flows at the inlet to the individualizer  122  and elsewhere, except for short intervals of order one second when neither measurements nor transports are taking place. The flow  134  out of the lint box  130  is not the same, since other flows enter the lint box.  
         [0037]    Filter  136 , blower  138  having suctions of tens of inches water column at 150 CFM (4.2 m 3 /min), and motor  140  of about two HP are well known in the art. Note that motor  140  is driven by a variable speed inverter  142  which is controlled by computer  112 . Among other control parameters, system suction is maintained constant by use of the variable speed control of motor  140 .  
       Micronaire, Maturity and Fineness Via Continuous Compression Air Flow Permeability Measurements  
       [0038]    [0038]FIGS. 2, 3,  4 ,  5  and  6  show continuous compression air flow permeability measurement apparatus  400  comprising turntable  401  which rotates above baseplate  403  and is driven by gearmotor  406  via gearbelt  408 . Gearmotor  406  is controlled by computer  112  via controller  407  and moves between two primary positions, “Load/Measure” (FIG. 2) and “Transfer/Eject” (FIG. 5), established by microswitches  410 ,  412 . While rotating between these primary positions, turntable  401  is lifted above baseplate  403  by sealing cylinder  411  by just enough clearance (about 0.04 inch (1 mm)) to allow free rotation, without damage to various seals (not shown). When turntable  401  is at one of the primary positions, cylinder  411  drives turntable  401  toward baseplate  403  and compresses the seals and holds it in position for other operations, including the continuous compression of the “plug,” which involves forces up to 200 pounds (90 kilogram-force).  
         [0039]    On turntable  401  are two diametrically opposite compression/measurement chambers  405 A and  405 B which enable parallel testing a first sample  102  while loading a second such sample  102 . Compression chambers  405 A,  405 B have approximately one hundred small perforations (FIGS. 2 and 5), having hole diameters of about 0.07 inch (1.8 mm), through which measurement and eject air components flow. Compression chambers  405 A and  405 B are cylinders, closed at one end, with perforations in the cylindrical walls and endwalls. Sample handling is described first below, followed by a description continuous compression permeability measurements.  
         [0040]    [0040]FIG. 4 is a larger scale view of FIG. 1 showing only the MMF module  400  in side view. Described hereinabove, in the systems section, is the manner in which operator  101  guesses at 15 gram sample  102  weight, which sample  102  is then conditioned and tested for Color and Trash, delivered by belt  118  to individualizer  120 , and then arrives at the input of MMF module  400  in an ideal state for permeability testing, except for the guessed weight. Precisely measured mass is essential for rigorous permeability measurements required for Micronaire, Maturity and Fineness, MMF. Use of air flow rate sensor  402  and mass concentration sensor  404 , manufactured by PPM Inc., Knoxville, Tenn., enables the determination of mass flow rate into module  400  and how, upon reaching a mass set point M e SP, the MMF module  400  internally bypasses the excess part of guessed weight sample  102 . Described next below is how this bypassing is handled internally to MMF module  400 , as well as the movement between the two primary positions for compression chambers  405 A and  405 B.  
         [0041]    Referring first to FIG. 4, it can be seen through cutaway section  414  that the two component flow  415 , comprised of air and individualized entities from samples  102 , and arriving at the input of MMF module  400  from the output of individualizer  120 , enters a hole  416  in valve body  418 , and is conducted via solid conduit  420  into perforated conduit  422 , wherein the individualized entities are separated. Air  424  moves through the entities and through the perforations in conduit  422  into a negative plenum that connects internally to suction conduit  453  (FIG. 3) which in turn connects to lint box  130 . The entities  426 A from original sample  102  remain within the interior of conduit  422 . Upon reaching the mass set point M e SP, as determined by computer  112  in step-wise summation response to volumetric flow rate sensor  402  and electro-optical mass concentration sensor  404 , valve body  418  is pulled down by air cylinder  428  such that the remaining portion of the guessed weight sample  102  is bypassed to lint box  130  and loading cylinder  449  is isolated. We refer to this portion of original sample  102 , which achieved the desired mass set point, within narrower tolerances than operator guesswork, as  426 A through  426 D, as it progresses through the MMF module  400 .  
         [0042]    As soon as the longer duration of either achieving the predetermined entity set point mass  426 A in perforated conduit  422  or as soon as the permeability measurement taking place in  405 A is finished (see below), turntable  401  is slightly lifted by sealing cylinder  411  and rotates clockwise from the “Loading/Measurement” position seen in FIG. 2 to the “Transfer/Eject” position seen in FIG. 5. In FIG. 2, compression chamber  405 A is in the “Measurement” position while chamber  405 B is in the “Loading” position. There is no corresponding hole in baseplate  403  below chamber  405 B, so chamber  405 B is isolated. “Loading” in this case refers to the set point sample mass  426 A which resides in perforated pipe  422 , FIG. 4. The “Loading/Measurement” duration may be about 20 seconds whereas the permeability measurement duration may last 10 to 15 seconds.  
         [0043]    After the turntable  401  reaches the “Transfer/Eject” position seen in FIG. 5, and which position is determined by actuation of microswitch  412 , transfer cylinder  430 , FIG. 4, drives the set point mass portion  426 A of sample  102  up into compression chamber  405 B, FIGS. 4 and 5. The top of piston  432  stops just below the bottom of turntable  401 , or flush with the top of baseplate  403 . Almost simultaneously, compressed air nozzle  434 , FIGS. 3 and 5, blows the prior set point mass  426 C portion of prior sample  102  out of compression chamber  405 A, through a hole in baseplate  403 , onto balance  436 . The time duration at this “Transfer/Eject” position is only one to two seconds, after which the turntable  401  rotates again to the next “Load/Measure” position, as determined by microswitch  410 .  
         [0044]    It is important to note that this rotation of two compression chambers permits parallel operations, thus reducing overall testing time.  
         [0045]    Before disclosing the continuous compression permeability measurement aspects of the invention, we complete the sample handling by noting in FIG. 3 that the ejected sample  426 D, after being automatically weighed by balance  436 , is blown into hole  450  in bypass tube  451  by a pulse of compressed air from nozzle  455 . Hole  450  is produced when tightly-sealed door  452  is opened by actuator  454  (FIG. 4). Ejected sample  426 D then passes via pipe  453  to lint box  130 . Balance  436  acquires the precise mass of sample  426 D while the permeability of the next sample is being measured and while the sample after that is being loaded, again, in parallel operations involving three successive samples  102 . The finished sample  426 D is blown into hole  450  during a turntable  401  rotation so that the system suction is not disturbed during loading or measuring operations.  
         [0046]    [0046]FIG. 6 is a cross sectional elevational view whose cut lines are indicated in FIG. 3. Test sample entities  426 C are seen in concentric and identical internal diameter cylinder bores  461  in chamber cap  460  and turntable  401 . Sample compression piston  462  sits in a similar bore in baseplate  403 . These bores are precision-aligned and have diameter of nominally 2.060 inches (5.232 cm).  
         [0047]    The samples  426 C arrive in this “Measurement” position as follows: In the “Transfer/Eject” position (FIG. 5), the transfer piston  432  in FIG. 4, at its most extended extreme, is at the same flush position with respect to baseplate  403  as the measurement piston  462  in FIG. 6 is in its most retracted extreme. Turntable  401  slightly elevates and rotates, carrying sample  426 B across the tops of the two pistons, fully extended piston  432  of FIG. 4 and fully retracted piston  462  of FIG. 6, whose tops are, during the transfer, flush with the top of baseplate  403  or the bottom of turntable  401 . Upon reaching the measurement position, the designation of sample changes from  426 B to  426 C, the latter of which is seen in FIG. 6. Note also in FIG. 6 that compression piston  462  is, at its most retracted position, in a precise position assured by the bottom of piston  462  striking the top of mounting plate  464 .  
         [0048]    Piston  462  is perforated, also with about 100 holes as in the identical compression chamber tops  405 A,  405 B. Air flow Q, typically in liters/min, measured by flow sensor  470 , is delivered at nearly constant pressure difference ΔP, as measured by sensor  472 , typically in inches of water column, and permeates sample  426 C in compression chamber bore. As the volume of the sample  426 C is reduced, or the compression force on the sample is increased, the air flow permeability of the compressed sample  426 C “plug” decreases. Also during the continuous compression, as y decreases from a maximum of about 2 inches (5.08 cm) to a minimum of about 0.5 inch (1.27 cm) over a time duration of about ten seconds, the force on the plug increases, as is measured, approximately, by the force F on the piston in air cylinder  466 . (More accurate force measurements, those on the plug itself, which range from about zero to over 200 pounds (90 kilogram-force) force, result from installing force transducer between piston rod  465  and compression piston  462 .) Permeability (Q, ΔP) and force F measurements are acquired by computer  112  as frequently as desired but, for out purposes, we have found that sampling rates of ten per second are adequate.  
         [0049]    What matters in the characterization of air flow through fibrous media is rigorous measurement of the permeability of the sample  426 C plug and of sample mass and compression volumes or bulk mass densities, g/cm 3 . It does not matter whether permeability is measured at constant pressure with variable Q, as described above, or at constant Q and variable delta pressure. By permeability we mean K=ΔP/Q2. Thus, in most basic terms, the physical responses of air flowing through a fibrous sample  426 C are completely described by the sample  426 C mass, the volume yA, the compression or bulk density of that known mass in that known volume, and the flow Q through the variably compressed plug  461  and pressure differential ΔP across it, or strictly, plug permeability K=ΔP/Q2. (Gas composition and temperature and absolute atmospheric pressure are needed only in the most exacting of research-type measurements.) Our apparatus measures all of these parameters plus force F during the continuous compression precisely, accurately and with digital sampling so frequent as to approximate continuous measurement, so the air flow permeability characteristics of the unknown sample are completely described. For emphasis and symbolic simplification, air flow permeabilities K for a wide range of bulk densities are the basic data product of the invention.  
         [0050]    But permeability of known mass of sample at continuous compressions, no matter how rigorous or how well measured, is of little use currently in the classification of cotton. Our basic data must be “calibrated” in terms of more familiar fiber quality parameters like “micronaire,” “maturity” and “fineness.” These calibrations follow known statistical methods, including nonlinear multiple regressions between the continuous compression permeability readings of our MMF apparatus and samples having the desired quality parameters, which measured quality data are provided by others, including the USDA.  
         [0051]    Thus, FIG. 7 is a performance graph comparing micronaire measurements made employing embodiments of the invention (vertical axis) to USDA micronaire cotton standards. As noted in the Background of the Invention, micronaire is now a dimensionless measurement, since it has been realized that the fineness linear density dimensions in μg/in are incorrect for micronaire.  
         [0052]    While specific embodiments of the invention have been illustrated and described herein, it is realized that numerous modifications and changes will occur to those skilled in the art. It is therefore to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit and scope of the invention.