US3198006A

US3198006A - Recording of freeness of paper making stock

Info

Publication number: US3198006A
Application number: US214420A
Authority: US
Inventors: Williams David Joseph
Original assignee: Australian Paper Manufacturers Ltd
Current assignee: Amcor Pty Ltd
Priority date: 1958-02-21
Filing date: 1962-08-02
Publication date: 1965-08-03
Anticipated expiration: 1982-08-03
Also published as: GB913659A

Description

Aug- 3, 1965 D. J. WILLIAMS 3,198,006

RECORDING OF FREENESS OF PAPER MAKING STOCK Filed Aug. 2, 1962 6 Sheets-Sheecl 1 ATTORNEY Aug- 3, 1965 n. .1. WILLIAMS 3,198,006

RECORDING 0F FREENESS 0F PAPER MAKING STOCK Filed Aug. 2, 1962 6 Sheets-Sheet 2 INvEN-roa ATTORNEY Aug. 3, 1965 D. J. WILLIAMS RECORDING 0F FREENESS OF PAPER MAKING STOCK Filed Aug. 2. 1962 6 Sheets-Sheet 3 INvENToR DAVID JOSEPH WILLIAMS A'I'To RNEY Aug- 3, 1965 D. J. WILLIAMS 3,198,006

RECORDING OF FREENESS OF PAPER MAKING STOCK Filed Aug. 2, 1962 6 Sheets-Sheet 4 36 if J4 L" 4f 47 Il n 41 411 4d 4f 11a INvENToR DAVID JosaPI-I WILLIAMS i BY A-I'To R N EY ug 3, 1965 D. J. WILLIAMS 3,198,006

RECORDING OF FREENESS OF PAPER MAKING STOCK 6 Sheets-Sheet 5 Filed Aug. 2, 1962 INvENToR DAvl o Jos EPH WsLLmMs BY 2m Jl/W ATTQRNEY Aug. 3, 1965 D. J. WILLIAMS 3,198,006

RECORDING OF FREENESS OF PAPER MAKING STOCK 6 Sheets-Sheet 6 Filed Aug. 2, 1962 Fans/'armen L I I I I I I I I Mains Supp/y.

Scrvograp/I Racorde/z LL --l Canro/ CubIc/e The/mision oom INvENToR DAVID JOSEPH WILLIAMS BY LOM/w; W

ATTORNEY United` States Patent() ice 3,198,006 RECRDENG F FREENESS F PAPER MAKING STOCK David Joseph Wiliiams, East Ivanhoe, Victorin, Australia, assignor to Austraiian Paper Manufacturers Limited,

Matraviie, New South Wales, vCornrnonwealth ofA Australia Filed Aug. 2, 1962, Ser. No. 214,420 Claims priority, application Australia, Feb. 21, 1,958,

35,503/58 Claims. (Cl. '7S-63) This invention relates to recording the freeness of paper making stock. The application is a continuationin-part of my application Serial No. 793,517, filed February 16, 1959, now abandoned.

In the past, such measurements have usually necessitated a series of tests carried out periodically by hand. It is well known, however, that manual investigation is subject to `substantial errors occurring wherever the human element is involved, in addition to occupying a great deal of time. Certain types of automatic recorders have been known or used but many of these have serious disadvantages. Many, for example, require a constant pulp temperature and consistency which are difficult to realize in practice. Various forms of recorders have been devised which seek to obtain a freeness value by measuring the conductivity and/or dielectric constant of the pulp. This method, however, often suffers inter alia, from the disadvantages of the non-uniform pulp distribution in the measuring zone.

It is the primary object of this invention-to provide improved apparatus for accurately and conveniently measuring and recording the freeness of paper making stock while obviating or substantially reducing the disadvantages inherent in freeness recording devices known and used hitherto, and without interfering with normal operations of the paper making machine.

The above and other objects and advantages will bccome apparent from the following description with reference to the accompanying drawings which relate to a preferred form of the invention, it being understood that the invention is not limited to the precise arrangement shown.

In the drawings: p

FIGURE 1 shows in section the general arrangement of a preferred apparatus in accordance with the invention for continuously recording the freeness of paper making stock;

FIGURE 2 is a plan View of the apparatus illustrated in FIGURE 1; l

FIGURE 3 is an enlarged section of part of the appavratus illustrated in FIGURES 1 and 2, and shows an arrangement for sensing the stock concentration;

FIGURE 4 is an enlarged section of part of the apparatus illustrated in FIGURES 1 and 2, and shows a container for receiving stock; i

FIGURE 5 shows details of part ofthefreeness-testing section of the apparatus illustrated in FIGURES 1 and 2;

FIGURE`6 is a plan View of the freeness testing section shown in part in FIGURE 5;

FIGURE 7 is acircuit diagram showing a preferred electrical system for usein connection with the apparatus of FIGURES 1 to 6, and

FIGURE 8 is a schematic layout showing in diagram- 3,198,3@6 Patented Aug. 3, 1965 matic form the relationship between certain components of the apparatus illustrated in FIGURES 1 to 6.

PULP DILUTION AND DELIVERY SYSTEM Referring more particularly to FIGURES 1 to 4, the pulp supplied, for example, from a head box Vand through a exible `hose (not shown) is fed to feeding tank 1 which preferably incorporates a constant head device such as a weir 1a from which the overflow may be redirected tothe machine chest. From feeding tank 1, stock is supplied to dilution tank 5 where it is diluted to approximately 0.8% concentration with water supplied through a reducing valve 5a which is advantageously set to a pressure of the order of 15 lbs. per square inch. The diluting water may pass into tank 5 through a fishtail jet 5b applied across outlet Se from tank 1 to ensure thorough mixing.

Dilution tank 5 may also be provided with a weir such as shown at 5d to give a constant head under which the diluted pulp discharges through orifice 5c to the delivery channel 2 which preferably has 'a slight inclination downwardly in a direction away from orifice 5c towards its outlet end 23. Overflow from Weir Sd may also be directed into a common overflow conduit 5f leading, for example, back to the machine chest (not shown). Delivery channel 2 may befixed to the orifice 5c of dilution tank S, for example by means of clamping plates 3, and a seal may be effected if desired by using a rubber or like insert between channel 2 and orifice 5c. In addition, baffle means, such as a triple plate baflie may be situated at the orifice `5r: to minimize fiow pulsations along the delivery channel 2.

Referring more particularly to FIGURE 3, stock concentration variations (viz. variations in the concentration of oven-dry fibre per given quantity of fluid) are sensed by electronically detecting the rise andfall of a fioat 7 mounted in delivery channel 2 for example by means of a rod or rods 7a pivotally mounted at one end on a pin 16 fixed relatively to channel 2 and` at the other end to an `appropriate bracket 18 attached to iioat 7. The float also has attached to it, preferably by means of a pivoted connection 17, an upstanding rod 12,preferably of copper, constrained to move substantially vertically, i.e. in the direction of its length, and having aixed to its upper end an armature or slug 7b (e.g. a length of mild steel), movement of which modifies the induced voltage in4 the windings of a differential transformer denoted generally by 9 and described more fully hereinafter with reference to FIGURE 7. The Vmovement of float 7 and its associated rod 12 and slug 7b may b'e stabilized and regulated by means of counterweight` 19 fixed to lever 20 pivoted at- 21 and passing through an aperture 22 in rod 12.

Stock passes from the outlet end 23 of delivery channel 2 into container 24 situated in tank 4 (see FIGURE 4).A Container 24 advantageously holds approximately 600 mil. .of stock'` which, together with the quantity of stock flowing into

freeness vessel

14, 14a (to be described more fully hereinafter) while the rotary Valve 6 `is open, provides a test quantity `of stock just in excess of the volume of the freeness vessel. The discharge from container 24 is via an outlet 25 in which maybe. inserted a stopper-26 of rubber orlike material adapted to hold a length of tube 27, and it will be evident that` the posi- V which is preferably of bronze.

tioning of tube 27 and consequent adjustment of the top 2S thereof permits of a tine degree of control over the total volume of stock discharged into the freeness vessel, thus avoiding excessive overflow. Outlet may be sealed against rotary valve 6 by gasket 6a, preferably of foamed isocyanate plastic material.

Stock falling into container 24 from the delivery channel 2 has the desirable effect of agitating stock awaiting discharge to the freeness vessel. Overflow from container 24 may be passed into the common return system associated with conduit 5f, thence to be lead back to the machine chest.V

FREENESS TESTING SECTION Referring more particularly to FIGURES 5 and 6, the freeness testing section of the unit includes a vertical main drive shaft 49 driven preferably through a reduction gear box 49e from motor 31 at a speed preferably of the order of about l revolution per minute. To shaft 49 there may be ixed a spacing block 4t) of bronze or other suitable material and into which two bronze or like bushings 29, are sweated to provide diametrically opposite bearings for two independent horizontal freeness vessel supporting shafts 41, 41', advantageously of stainless steel. Each of

shafts

41, 41 has a

recess

32, 33 respectively by Which the lateral position of the shaft may be iixed by means of set screws 34, respectively, adjustable from the top of spacing block so that they protrude through bushings 29, 30 to locate their

respective shafts

41, 41.

The two freeness vessels are denoted generally by 14, 14a and may be formed from bronze tubing. Each is advantageously of about l litre capacity and has a threaded bottom portion adapted to receive a wear-resistant retaining ring 36 which is arranged to hold in position a Canadian standard freeness draining plate 37.

' Two collars 3S, 39 may be fitted to each vessel one (38) above, and the other (39), below a driving ring 41e attached to supporting shaft 41 to hold the freeness vessel in position relatively to driving ring 41C while undergoing a washing stage in which the vessel is unsupported by the base track element 45, a preferred form of Which is described hereinafter.

Collars

38, 39 are of sufliciently large internal diameterrto slide over the

vessels

14, 14a to which they are held, for example, by grub screws 14].

The upper collar 38 has a skirt 14g of a diameter greater than the external diameter of driving ring 41C. This skirt forms a canopy to prevent plup from accumulating around the driving ring. The necessary freedom of movement of the vessel about the driving ring is thereby maintained. As the driving ring 41C engages the skirt 14g, the vessel is pulled rather than pushed and this is an important factor in reducing vibration or judder. A section 14h may be cut from the top rear edge of each vessel to divert overilow to the gear.

A pinion 42 is fixed on each

vessel supporting shaft

41, 41 near the spacing block 40, and as the vertical main drive shaft 49 is rotated, the stage is reached where pinion 42 is caused to engage geared sector 43 fixed to the base suppor-t (indicated generally by 43a) of the freeness vessel assembly. In this manner, each

vessel

14, 14a may be completely rotated at the appropriate stage about an axis parallel to its supporting shaft for receipt of stock samples, for discharge of the samples, and for cleaning, p

4 Each vessel supporting shaft 41 is advantageously fitted with a loose roller 11, 11a adapted to run o n ring Fitted substantially diametrally beneath ring 15 is a bearing support strap 44. in the centre of which is mounted the geared sectorA 43 and the supporting block 4l). Upward movement of shaft 49 may be prevented by a sleeve 49a kor the like member placed between the bottom of the bearing support strap 44 and the head of a retaining bolt 49b which may bescrewed into the bottom end of the vertical main" driveshaft 49. The top of shaft 49 may be coupled to section may be housed to advantage an output shaft of the reduction gear box 49e through a iiexible coupling 10.

The rotary valve 6 which is mounted on the vertical main drive shaft 49 just above the

vessels

14, 14a is preferably an aluminium disc having apertures 6d so located that each is immediately above one of the freeness vessels. A bronze flange 6b may be bolted to the centre of this disc and may be suitably bored for fitting onto the vertical main drive shaft 49 upon which its position may be maintained by means of grub screw 6c.

The base track element 45 is preferably of ground and polished stainless steel over which the vessels are driven for approximately 240 of each cycle. The track element 45 may be bolted to the bottom of ring 15 by means of spacers 15a of bronze or other suitable material, which spacers provide a gap for spray water and any excess pulp to pass through the drainage system beneath the vessels. The exposed part of track element 45 forms a seal with retaining ring 36 on the bottom of each vessel for substantially 180 of the cycle. Following this section, the track element 45 is cut away to form an aperture 46 for approximately 40 so that the pulp may drain freely while the vessel passes over this aperture, the drainage period being approximately l0 seconds.

The ixed geared sector 43 is preferably placed so that when the vessel leaves the drainage section, sector 43 is engaged by pinion 42 on the supporting shaft 41, the shaft being thus caused to rotate to `such an extent as will invert the vessel 14 thus discharging the tested sample, and after the vessel 14 has passed over suitably located washing sprays 47', 47, 47', to return it to this former upright position. Vessel 14 then slides onto the base track element 45 and the pinion 42 and geared sector 43 disengage. It will be evident that loose rollers 11, 11a adapted to run on ring 15 reduce the load on the vessel supporting shaft bearings 29, 3) whenv pinion 42 and geared sector 43 are engaged and the vessel is unsupported by track element 45. Rollers 11, 11a may be held in position by any suitable means, for example by appropriately located rollers 11b, 11C.

In addition, rubber bladed sweepers 41d may be pivotally mounted on the vessel supporting shafts 41 to ride. on ring 15 ahead of the rollers and to deflect any accumulated pulp into the drainage system.

The entire apparatus may be levelled and bolted in three positions to the side of a stepped cone 13 which is preferably of stainless steel. The receptacle for the drainage water may be fitted into the step of the cone and the tested stock, spillage and spray ,water may pass into the centre to drain via the outlet 13a at the centre of the lower section.

Pinions 42 and geared `sector 43 may, if desired, be protected from spray Water by a cylindrical cover 43b for example of galvanized iron and situated adjacent the main drive shaft 49.

Spouts or nozzles 47, 48 for preferably in the form of ishtail sprays, are advantageously situated at intervals around the track 45. One jet 47 may be so arranged that it directs Water onto the bottom of the freeness plate 37 when the vessel commences to invert. ,A second jet 47 is preferably placed at approximately 70 to the horizontal and in the direction of travel so as to spray into the vessel when the last mentioned isv inverted and a similar function is performed by the third jet 47. A fourth jet 47 sprays the track at the point where the vessel tirstr meets it, while the fifth and sixth jets 48 and 48' direct their jets over the track, the jet 48 being placed just after the lling point and directing its jet along the track against the direction of rotation to disperse any overflow from the vessel.

A vertical shaft 49d from the reduction gear box 49C may be extended via a iiexible coupling to actuate microswitches 60, 61 (FIGURE 7) or like timing means controlling the Vsequence of operations. This programming in a metal housing providing jets of water 5. `such as shown at 8, preferably supported on the framework of the apparatus. i

TIMING OF THE INSTRUMENT Referring now also to FIGURES 7 and 8, the timing for a two-vessel (14, 14a) system may be est-ablished so that during each 60-second interval of rotation of the vertical main drive shaft 49, both vessels are filled, the cumulative drainage rate registered and the vessels rotated through 360 about axes parallel to their supporting shafts for washing purposes.

Taking the beginning of the drainage period of vessel 14 as the commencement of the cycle, solenoid valve 49e which empties measuring tank 491c is set to close just as the leading edge of the vessel reaches the drainage testing section. It remains closed until approximately the 51st second while the drainage water from both vessels accumulates in measuring tank 49j and raises a ilo-at 49k attached to the lower end of longitudinally -slidable rod 49g projecting into differential transformer 49h whereby the water level in measuring tank 49j" is sensed. VThe solenoid valve 49e then opens until the 60th second to allow the drainage w-ater to iiow from measuring tank 497i To meet this requirement, the solenoid `valve may be operated :by a 54 cam `segment of microswitch `61 set to start at 306 in the 360 cycle.

The combination of valves V and V15 together with the 8-microfarad storage capacitor 57 between the cathode V5 and ground supplies to recorder 66 1a voltage proportional to the mean peak value of the tests. The response to any increase in freeness is immediate, but downward response is normally limited by the rate of discharge of storage capacitor 57. This is compensated for by a second cam-operated microswitch 60 arranged to connect a bleed resistor 59 across the storage capacitor 57 when every peak value is reached during the 49th and 50th seconds of the cycle, so that in the event of a reduced freeness, capacitor 57 is permitted to discharge rapidly to the new value.

The cam of microswitch `60 preferably has one 12 se-gment which is suit-ably located to operate over the 294 to 306 sector of the cycle. All switches preferably have contacts connected in parallel for the sake of reliability.

DESCRIPTION OF CIRCUIT (i) F reenes's measurement A preferred form of dierential transformer used for the purpose of this invention may consist of two substantially identical sections placed side-by-side. section may have about 5,000 turns, for example of 0.0075 double tough enamel-covered wire on both primary land secondary windings. The former-s may be turned from ten-inch lengths of polystyrene rod, preferably of about two inches in diameter, to a diameter of one inch. .Flanges of 5%16 of an inch may be -left at the ends. Each former preferably has an axial bore along its entire length. Inone of the formers, the bore receives a rod attached t-o the iioat in delivery channel 2 or measuring tank 49j, as the case may be, while in the other former, the bore accommodates -any balancing slugs which may be necessary. These transformers may be evenly wound. The primary windings of each section are preferably con nected in parallel, the secondary windings being series opposed.

The differential transformer associated with, and located above, measuring tank 49f is denoted generally by 49h and includes primary and

secondary windings

50 and 51 respectively. The output voltage from transformer 49h, modified by changes in position ofV rod 49g therewith, is applied to an amplifier associated with the -freeness` channel. Then amplifier includes a pentode 52 6517 (V1) feeding pentode `513 6SI7(V2) which in turn feeds metering diode 54 1/z-6H6(V3), the rectified current of which is measured by a SO-microamp meter 55 in the cathode circuit. The D.C. voltage at the cathode of 54` is applied Each d to the transient peak volt meter triode 56 (V5) (1/26SN7) through which the eight microfarad (preferably paper) condenser 57 is charged to a peak value representing the volume arising from the measurement of each test sample. Thevolt-age of this condenser is applied to the control grid of one section of the differential metering amplifier 58 formed by V1.1 and V15 (6SN7). With zero input, the

cathode currents through 5S (V14 and V15) lare .balancedV by the variable bias control. In this condition both cathodes are at the same potential above ground. When a voltage appears at the grid of V15 its cathode current increases and the potential difference which then exists between the cathodes is measured and recorded in recorder 66 and the series resistance of 150,000 ohms of which 100,000 ohms is variable. The bleed resistance 59 in the circuitry associated with the transient peak volt meter charging capacitor 57 is such that a decay of approximately 2% of the voltage to which it is charged occurs during the period of one minute between tests. As this imposes a considerable limitation on the speed of downward response of the Voltmeter, programming microswitch 60 on the extended vertical shaft 49d connects the shunt resistance 59, preferably of about 10 megohrns, across the capacitor when the peak value of each test is reached. In this way the overall discharge rate is not materially affected but the instrument is able to follow .a downward trend almost as quickly `as an upward trend. yIt is most important that the lead from capacitor 57 to microswit-ch 60 be of high insulator resistance.

The temperature measuring channel includes a thermistor bridge, denoted generally by 62 including thermistor 63 (eg. of the Stantel type) in which temperature variation is detected by a change in resistance. The bridge imbalance thus brought about is amplified by a two stage amplifier, one stage 64 6517 (V6) feeding another 65 6SK7(V7). The output from the latter stage V7 feeds a phase-discriminating rectifier 67 (V8 and V9) comprising a dual-diode arrangement such as 6H6, from which is derived either a positive or negative D C. voltage of amplitude and polarity dependent on the magnitude and direction of the temperature variation.

This D.C. voltage is then applied in an appropriate proportion through lead GS to the grid circuit of tube 58 (V1.1 and V15), as selected by adjusting the temperature correction potentiometer 69. It then causes the cathode current of section V1.1 to vary and so adds to, or subtracts from, the potential difference existing between the cathodes of V1.1 and V15 of tube 5S due to the freeness value.

(iii) The stock concentration measuring section includes a differential transformer denoted generally by 9 (FIGS. l, 2 and 3) including primary and

secondary windings

71 and 72 respectively. The voltage induced in differential transformer 9 is modified by the rise and fall of float 7 with its associated rod 12 and slug 7b. The rod 12 is preferably located midway between the two sections of the transformer at the desired stock concentration. Under these conditions the voltages in both secondary windings '72 balance, and there is no output.

As float 7 rises or falls with stock concentration variation, an imbalance voltage is induced and is applied to a stock concentration channel amplifier including tubes '73 and 74 similar to that used in the temperature channel, with the output from 74 being applied to the phase discriminating rectifier 75 formed by V12 and V13 (6H6) by which means a positive or negative D.C. voltage is similarly derived. This voltage is also applied, through lead 76, in an appropriate proportion as selected by the S/C Correction potentiometer '70, to the grid circuit of section V11 of tube S5. It then similarly causes the cathode current of section V11 to vary and so adds to, or

Temperature correction Stock concentration correction subtracts from, the potential difference existing between the cathodes of V1.,= and V due to the freeness value.

These correction controls are advantageously in parallel in the grid circuit of section V14, and the corrections for temperature and stockv concentration variation may oppose or assist as required by the circumstances. Y

The gain of the second stages of the stock concentration and temperature channels is automatically controlled by the output of the freeness channel as derived from the cathode of V15. A higher freeness increases the gainof these channels and maintains any correction voltage in the appropriate proportion. As the correction characteristic for stock concentration, which is by far the most frequent variable, flattens at a freeness corresponding to approximately 400 Canadian Standard free- Vness, Va diode (V4) is connected from the automatic gain control line to ground and biased so that it bypasses any automatic gain control voltage above that corresponding to a freeness of 400 Canadian Standard freeness.

Temperature and stock concentration variations are indicated separately on -0-25 microamp meters '77 and 7S respectively, in their respective discriminator circuits 67 and 7S.

All three bridge circuits may be supplied from a common 6.3 volt 50-cycle supply, and the reference voltage for the discriminators derived, for example, from a 12%0500 ohm line-transformer '79, the secondary 8) of which is centre-tapped and grounded.

The main drive motor 31 is advantageously a halfhorse power single-phase 1425 r.p.m. totally enclosed unit preferably protected by a Westinghouse Sentinel Thermal Overload 8l.

The power supply uses a Trimax TP2246 325 v. per side 150 milliamp transformer '79 and a capacitor input double section `lter 82. The output is regulated at about 300 Volts by two VR150/30 regulators 83 in series.

The following table refers to the schematic layout illustrated in FIGURE 8, and indicates the duty performed by the most important electrical leads connecting the various components.

SCHEDULE OF WIRE NOS.

Y Power supply Wire Nos. Duty 4', 15', 19'--. Neutral. 2', 13 VTVM (low loss) shunt leads to 10 meg. 10', 11' LT. D.C. to Recorder Movement. 5', 6', 17', 16' 6.3 v. A.C.N.

one vessel member of constant volume operatively connected to a rotating means to rotate said vessel member in a circular path, said vessel member receiving during a portion of said circular path a sample of substantially constant volume of said paper making stock, said vessel member draining during another portion of said circular path the Water from said sample of paper making stock, tank means for receiving the drained Water, float means operatively connected to a further dierential transformfer-,type measuring means disposed in said tank means for measuring the volume of the drained Water, temperature measuring means disposed in said tank means to measure the temperature of the drained water, means connecting said differential means for sensing variations in the consistency of said paper making stock and said temperature measuring means to said further differential means to apply corrections to the measurements of the volume of the drained Water to obtain freeness of said paper making stock, and means for recording the freeness of said paper making stock.

2. An apparatus according to claim 1 in which said freeness testing assembly further includes Washing means to Wash said vessel member during the remaining portion of said circular path, and means operatively connected to said rotating means to invert said vessel member during this remaining portion of said circular path so that said vessel member is thoroughly Washed to remove paper making stock therefrom before receiving another sample.

3. An apparatus according to claim 1 in which each of said differential transformer-type measuring means comprises a differential transformer having rod means containing on `one end, which is movable within said transformer, slug mean-s to vary the :output of said transformer, the other end of said rod means being connected to said sensing means and oat means.

4. An apparatus according to claim 1 in which said freeness testing assembly `further includes another vessel member, and a track element disposed beneath and on which the bottom of said vessel members ride to form a seal during the portion of said circular path in which said vessel members receive said sample of the paper making stock, said track element having an aperture therein to allow the drainage water to pass into said tank means.

5. An apparatus according to claim 1, and further comprising valve means for emptying said tank means, and programming switch means operatively connected to said rotating means to operate said valve means to periodically drain said tank means after the freeness of a sample therein has been recorded.

References Cited by the Examiner UNITED sTATEs PATENTS 1,653,125 12/27 Schur 162-198 1,970,521 S/34- Harvey 73-63 2,022,010 11/35 Schopper 73-63 2,362,661 1l/44 Peters et al 73-453 X RICHARD C. QUElSSER, Primary Examiner. DAVID SCHONBERG, Examiner.

Claims

1. APPARATUS FOR CONTINUOUSLY RECORDING THE FREENESS OF PAPER MAKING STOCK COMPRISING A DELIVERY CHANNEL FOR RECEIVING PAPER MAKING STOCK DILUTED WITH WATER, SENSING MEANS OPERATIVELY CONNECTED TO A DIFFERENTIAL TRANSFORMER-TYPE MEASURING MEANS DISPOSED IN SAID DELIVERY CHANNEL FOR SENSING VARIATIONS IN THE CONSISTENCY OF SAID PAPER MAKING STOCK, A FREENESS TESTING ASSEMBLY DISPOSED ADJACENT SAID DELIVERY CHANNEL INCLUDING AT LEAST ONE VESSEL MEMBER OF CONSTANT VOLUME OPERATIVELY CONNECTED TO A ROTATING MEANS TO ROTATE SAID VESSEL MEMBER IN A CIRCULAR PATH, SAID VESSEL MEMBER RECEIVING DURING A PORTION OF SAID CIRCULAR PATH A SAMPLE OF SUBSTANTIALLY CONSTANT VOLUME OF SAID PAPER MAKING STOCK, SAID VESSEL MEMBER DRAINING DURING ANOTHER PORTION OF SAID CIRCULAR PATH THE WATER FROM SAID SAMPLE OF PAPER MAKING STOCK, TANK MEANS FOR RECEIVING THE DRAINED WATER, FLOAT MEANS OPERATIVELY CONNECTED TO A FURTHER DIFFERENTIAL TRANSFORMER-TYPE MEASURING MEANS DISPOSED IN SAID TANK MEANS FOR MEASURING THE VOLUME OF THE DRAINED WATER, TEMPERATURE MEASURING MEANS DISPOSED IN SAID TANK MEANS TO MEASURE THE TEMPERATURE OF THE DRAINED WATER, MEANS CONNECTING SAID DIFFERENTIAL MEANS FOR SENSING VARIATIONS IN THE CONSISTENCY OF SAID PAPER MAKING STOCK AND SAID TEMPERATURE MEASURING MEANS TO SAID FURTHER DIFFERENTIAL MEANS TO APPLY CORRECTIONS TO THE MEASUREMENTS OF THE VOLUME OF THE DRAINED WATER TO OBTAIN FREENESS OF SAID PAPER MAKING STOCK, AND MEANS FOR RECORDING THE FREENESS OF SAID PAPER MAKING STOCK.