US3073150A

US3073150A - Viscometer

Info

Publication number: US3073150A
Application number: US856962A
Authority: US
Inventors: James D Fann
Original assignee: Great Lakes Carbon Corp
Current assignee: SGL Carbon Corp
Priority date: 1959-12-03
Filing date: 1959-12-03
Publication date: 1963-01-15
Anticipated expiration: 1980-01-15
Also published as: AT244643B; NL258633A; BE597739A; GB903884A; CH411399A

Description

J. D. FANN Jan. 15, 1963 VISCOMETER 5 Sheets-Sheet 1 Filed Dec. 3, 1959 fairies @fazzzz Filed Dec. 3, 1959 Jan. 15, 1963 J. D. FANN 3,073,150

VISCOMETER 5 Sheets-Sheet 2 FIEE J.D.FANN

VISCOMETER Jan. 15, 1963 5 Sheets-Sheet 3 Filed Dec. 5, 1959 N mm ww J. D. FANN Jan. 15, 1963 VISCOMETER 5 Sheets-Sheet 4 Filed Dec. 3, 1959 ZIZZ/IZ-ZOW.

Japzes Far? J. D. FANN Jan. 15, 1963 VISCOMETER 5 Sheets-Sheet 5 Filed Dec. 3, 1959 United States Patent 3,073,150 VISCOMETER James D. Fann, Houston, Tex., assignor to Great Lakes Carbon Corporation, New York, N.Y., a corporation of Delaware Filed Dec. 3, 1959, Ser. No. 856,962 17 Claims. (Cl. 73-954) This invention relates to a device for measuring the consistency or viscosity of fluids. More particularly, this invention relates to a device for measuring the consistency or viscosity characteristics of fluids at, diflerent pressures and temperatures, and is particularly adaptable to measuring the changes in consistencies or viscosities of fluids which undergo a chemical reaction or physical change depending upon the pressure and temperature of the fluid, or on changes in the pressure and temperature, or on the length of time that the fluid is subjected to different or varying pressures and/or temperatures.

While the present invention is not so limited, it is particularly well adapted to measuring the viscosity characteristics of fluid materials commonly used in the oil and gas industry. In connection with the drilling of oil and gas wells, a variety of fluid compositions are subjected to elevated pressures and temperatures which occasionaly cause rapid increases in the viscosity of such fluid compositions which are pumped into the Well bores. In the completion of such wells, it is common practice to pump a cementitious slurry down into the well through casing, and force this slurry up through the annulus between the casing and the well bore. This operation is designed to seal off the overlying formations from the oil or gas producing zone with set cement. It is common knowledge that aslurry of Portland cement, with or without aggregates or other additives contained therein, tends to thicken and occasionally flash set in the well in a relatively short period of time. The deeper the well, the higher generally will be the temperature and pressure to which the cement slurry is subjected and thesev conditions aggravate the setting problem.

In view of the foregoing facts, there has been a great need for a device or an apparatus and a method capable of measuring the changes in viscosities of Portland cement, slurries and other fluids which will be subjected to varying temperature and pressure conditions in wells, as well as, or alternatively capable of measuring the time intervals required to reach various consistencies or viscosities under varied temperature and pressure conditions. These conditions may, for example, vary from atmospheric pressure to eighteen thousand lbs/sq. inch and from 80 to. 400 F. To accomplish the foregoing objectives it is de-. sirable to simulate well conditions as closely as possible. A typical time-pressure-temperature well-simulation schedule for cementing casing for a 14,000 foot well is as follows:

Time (Min.)

Pressure Temperature (p.s. i.) F.)

6, 760 134 7, 040 137 7, 320, 140 7, 600 143 7, 880 14s 8. 160 149- 8, 440 152 8, 710 155. 8, 990 158 9, 270 161 9, 550 164 9, 830 167 10, 110 170 10. 300 173 10, 670 176 10, 950 179 11, 230 182 185 11, 780 188 12, one 191 40. 9 12, 620 197 900 200 13, 180 203 13,390 206 The instrument herein described is suitably adapted to closely simulate the foregoing time-pressure-temperature. schedule as well as similar schedules.

Certain forms of apparatus have been devised by others to measure the changes in viscosity or consistency of Portland cement slurries under controlled time-pressuretemperature conditions. These devices generally, how. ever, are very expensive and physically quite cumbersome. They are normally retained in regional laboratories where consistency tests are made, It is, however, desirable to. have a portable consistometer which can satisfy the foregoing needs and which can be used on the well site to measure what the viscosity characteristics of cement slurry samples taken directly from cement trucks just prior to the pumping of the cement slurry into the well for cementing casing are likely to be.

The devices which have heretofore been used for testing cements, besides possessing the aforedescribed shortcomings, are further provided with paddles, agitators or similar means which continuously stir the cement slurry or other well fuid in the testing apparatus over a desired time-pressure-temperature testing cycle. When friable materials such as lightweight aggregates which are often used for lowering the weight of cement slurry and/ or for sealing or bridging ofl certain areas in the subterranean formation are incorporated into the cement slurry, these internal mixing devices tend to degrade or abrade such materials and'this will affect the viscosity and setting time of the cement slurry. Therefore, conventional laboratory devices currently in use cannot give a truly accurate prediction ofthe viscosity changes, and thetimes required for same for cement-aggregate slurries under actual well conditions.

The apparatus of the present invention is also adaptable for general studies of changes in viscosity of, oil well drilling fluids under varying conditions of pressure and temperature. It isalso useful in the testing of fluid compositions which are not necessarily connected with the drilling and completion of oil and gas wells. For example, the apparatus of .the present invention .is adaptable to measuring the viscosities of such materials as lubricants,

whether these be of petroleum base or some other base material, liquid foodstuifs such as syrups, molasses; anti freeze solutions, etc, and the times requiredfor viscosities of such materials tochange from one predetermined value to another predetermined value at temperatures and pressures either above orbelow usually prevailing atmospheric conditions. i

fluids which are characterized by undergoing chemical or physical reaction or change, depending upon changing conditions of time, pressure and temperature. It is a further object of the present invention to provide an ap paratus or device as well as a method for measuring the a time intervals required to reach various viscosities of fluids which are characterized by undergoing chemical or physicalreaction or change, depending upon changing conditions of time, pressure and temperature.

It is a further object of the present invention to provide a device which will achieve the foregoing objects with'fluids'which contain friable materials suspended therein and in which the degrading of such materials is minimized or substantially eliminated. V

- Further objects and advantages of the present invention will be apparent from the following detailed description particularly when considered in conjunction with the accompanying drawings. i

7 FIGURE 1 shows a perspective view of the fluid receiving vessel and associated elements employed in the present invention with most of the features shown in cross-section, and certain other features being represented schematically or diagrammatically.

FIGURE 2 shows a partial viewv of the device shown in FIGURE 1', but modified by the omission of the lower coil and therefore showing an alternative but generally less preferable device for carrying out the teachings of this invention.

FIGURE 3 is a partial cross-sectional view taken along the lines 3-3 of FIGURE 1 showing the pressure supply. means and associated features in greater detail than is shown in FIGURE 1.

[FIGURES 4 and 4A show a schematic diagram of the electrical circuits and various associated mechanical elements which complement the fluid receiving vessel of the present invention.

FIGURES. shows a block diagram of the electrical circuitsand various associated mechanical elements shown in FIGURES 4 and 4A. 4 1

In a broad embodiment the invention comprises a substantially non-magnetic container for the fluid to be tested, an electromagnetic winding surrounding a defined area or portion of the cavity or well of said container for establishing a magnetic field in said portion of said container, meanshaving an appreciable viscous. drag and being respon sive. to said magnetic field positioned within said container and freely movable in the fluid, means for intermittently and regularly energizing said windingwhereby said electromagnetically responsive movable means is caused to move into the resultant magnetic field, surfaces at both the top and bottom of. said defined area of said container which generate and transmit sound waves when struck by said movable means, and means responsive to the generated sound waves from which the consistency or viscosity of the fluid in said container may be determined. at any given time, or from which the time required for the consis t ency or.viscosityof the fluid to change from one value to another predetermined value may be obtained.-

'-In a preferred embodiment the invention comprises a substantially non-magnetic cylindrical container for the fluid to be tested, electromagnetic windings surrounding upper and lower portions'of acavit y orwell in said container for establishing magnetic fields in said portions of said c'ontainer, means having an appreciable viscous drag and being responsive to said fields positioned within-said co'ntai'nerfand'freelymovable'in .thezfluid, means for inttermittently and. regularly electrically energizing said windings .whereby'. said electromagnetically responsive movablemeans is caused to move into the. resultant respective magnetic fields and move toward the top and bottom surfaces of the cavity of said container, surfaces at both the top and bottom of said cavity which generate and transmit sound waves when struck by said movable means, means for converting said sound waves into electrical signals, means for amplifying said electrical signals, means for sensing variations in the viscosity of the fluid as the viscosity changes from one value to another predetermined value, electronic means for energizing the upper and lower electromagnetic windings tied in with or associated with the viscosity variations sensing means and means for recording when such predetermined viscosity variations occur.

The foregoing-described broad and preferred embodiments of thepresent invention will also become better understood after the attached drawings are studied in detail.

Referring therefore to the drawings and particularly FIGURE 1, there is shown a pressure cell or container 1 which is constructed .of a non-magnetic material capable of withstanding high pressures and also capable of conducting sound and heat. Stainless steel, brass and Monel metal are typical satisfactory materials. The container is provided witha fluid-tight, sound-conductive pressurewithstanding plug or closure 2.. This plug or closure 2 is threaded into the top inner threaded, tapered part 3 of the container. The center of the plug or closure 2 is hollow and cylindrical in shape. A pressure inlet stem 7 e 4 made of a magnetic material extends through this hol low center of the plug. The bottom 5 of the pressure inlet stem 4 is flanged. Between the top part of this flange and the bottom of the plug or closure 2 is placed a sealing gasket 6 which may be made from a resilient and temperature-resistant material such as Teflon. Teflon is a registered trademarkof the E. I. du Pont de Nemours Company for a plastic material consisting of a tetrafluorethylene polymer. A pressure seal nut 7 is threaded around a threaded portion of the pressure inlet stem 4 until the upward motion of the flange 5 of the inlet stem causesthe sealing gasket 6 to form an initial pressure seal. Any further pressure exerted on the contents of the container or pressure cell then assists in keeping the cell pressure tight for itsimply exerts more force on the flange against the gasket. placed between the' plug 2 and a seal nut 7 to keep them separated and to keep them from locking. Situated within the cavity or well 9 of the container is a thermowell 1 0 in which is-placed wires 10A of an electric thermometer for measuring the temperature of the fluid placed within said central cavity 9. The thermowell extends about halfway down into this main cavity or well of the container. Also situated within the main cavity 9 of the container is an electromagnetically responsive iron plunger or bob 11 which is cylindrical in shape, but hollow at its center. The top 12 of this iron plunger or bob is preferably made from a non-magnetic material such as brass. The iron plunger 11 during the operation of the device is caused to strike the top surface 13 of the main cavity of the container (which is also the bottom of the flange 5 of the pressure inlet stem 4) as well as the bottom surface 14. Both of these surfaces, being metallic, readily generate and transmit sound waves when struck by the bob.

- The top of? the pressure inlet stem 4 is threaded into.

a valve body 15. The'valve body 15 performs several functions. It serves as a coupling means between an external pressure line 16 and the pressure inlet stem 4. The pressure in this external pressure line, which line has its input or is coupled to the valve body 15 by means of threaded bolt '16A and nut 163, may be varied by a conventional hand pump (not shown) acting on a fluid such as oil. A conventional pressure gauge (not shown) is also in the line to show'the pressure at any given moment. A gasket or' pressure packing 17, shown in FIGURE 3,

A bronze thrust washer 8 is Mechanically coupled to the valve body 15 by means of a thumb-screw clamp 22 is a pick-up transducer 23 which is a moving coil in a permanent magnet magnetic field tuned to approximately 70 cycles per second.

Handle 24 may be turned to force the conical end of valve member 24B to seat into the opening of 24C in order to make the cell pressure tight before removing the external pressure line. This enables rapid cooling ofthe cell if desired such as by immersion in water.

The pressure cell having the features and attachments as thusfar described is designed for ready insertion in an external chamber or housing possessing several features. A shell or a can 25 immediately surrounds the side walls of the pressure cell. Immediatelysurrounding the shell or can 25 is a means 26 for heating or cooling the contents of the pressure cell. Typically it may be a resistance wire heater. The shell or can 25 may typically be made from a non-magnetic material such as aluminum and serves to support the heating or cooling means and to plates 29 are at the top and bottom of each of these elec- I tromagnets. The cell 1 rests on a flanged soft iron base 30. Soft iron support member 31 extends upwardly from foregoing elements.

A specifically designed pressure cell has a main central cavity 1 /2 in diameter and '5" high. A soft iron bob 11, weighing about 500 grams, displacing 72 cc. of fluid and having an outside diameter of 1%" and /2" diameter central bore is placed in the cavity after about 76 'cc. of the fluid to be tested, such as cement, has been placed therein. This causes the fluid being tested to rise to a height well above the top of the main cavity of the cell and insures that none of the :pressure'fluid will getinto'the' main cavity. After all the closures and othermechani-j cal elements shown in FIGURES 1 and. 3 are properly coupled to the cell 1 and valve body 15, a liquid, such as oil, substantially immiscible with the fluid being tested, is then pumped into the system through the pressure input means 16 and the cell brought to the initially desired pressure and temperature such as, for example 1750 p.s.i. and 80 F. required to start the test of the cement slurry.

In FIGURES 1 and 2 the cement slurry is marked X and the oil Z.

"In the system shown in FIGURE 1, the energizing of theftop 27 and bottom 28 electromagnets or coils sets up electromagnetic fields through the soft iron portions of the assemblage, including soft iron plates-29', the bob 11 and the flange 5 for the upper winding; and soft iron plates 29, the bob 11. iron base 30 and support member 31 for the lower winding. The brass top 12 of the bobll prevents the bob from sticking to the top surface of the cavity.

In the measurement of cementitious fluids such as are used in the oil-well industry, the attainment of viscosities of approximately 20, 70 and 100 poises are recognized as being significant. j The arrival or obtainment of -a 20- 6 poise viscosity level generally requires the most time and also generally-indicates that the viscosity of the cement from that stage on will increase rapidly; the arrival at the poise level signals the upper pumpable viscosity point limit; and poise indicates an unpumpable material. To know when or how long or under what conditions these viscosities can be expected to be reached witha particular cement about to be used is therefore very desirable for it will prevent the using of a cement improper for the particular well conditions encountered. This in turn will prevent needless effort and save much time and money by not using a cement which will prematurely set up.

Several factors or parameters are involved in the design of a pressure cell Whichwill successfully indicate when the cement reaches these viscosity levels. These include the time cycles of the electromagnets, that is, how frequently they are energized and deengerized and for what respective lengths of time; the sample volume and dimensions of the cavity; the plunger shape, volume, weight and dimensions; and the strengths. of the electromagnets and the relative forces exerted by each. The electromagnetic forces exerted by the coils not only are dependent on how long the coils are energized, but depend, also on their number of ampere turns and their magnetic circuits. These determine the'fiux density which in turn'determine the respective forces they exert on the plunger.

In-conjunction with the system shown in FIGURE 1 means are provided for energizing either the top or bottom coil, or both, thirty times per minute with the top coil being energized for just under 1 second each'cycle and the bottom coil being energized for 1 second each cycle. The top and bottom coils possess approximately 5000 ampere turns. With this arrangement the top coil exerts approximately 1 gravitational pull of force less on the bob than does the bottom coil which is assisted by gravity. g I g The relatively blunt end shape of the bob as distinguished from other possible shapes such as one with pointed ends, etc. is important to insure thorough circulation of the cement in the cavity as the bob goes up and down, and to therefore prevent spot hardening of the cement leading to erroneous results.

From the foregoing detailed general description of the device it will be appreciated that there are several critical factors involved in the design of the device of the present invention.

The top surface 13 and the bottomsurface 14 of the cavity 9 of the container are sound-responsive in nature, that is, they generate and transmit sound whenever they are struck by the top or bottom, respectively, of iron plunger 11. The sound waves so emanating from said surfaces are picked up by the transducer 23. Sounds will be generated only'when iron plunger 11 is in motion and strikes either of the aforementioned surfaces. This motion placed in the container may be or become so great that the iron plunger cannot reach a particular striking surface of the cavity during a given time limit in the cycle. This failure to reach astriking surface may be made a function of a measured calibrated viscosity, so that when such failure occurs-the operator then knows that the fluid has reached a predetermined viscosity level. These predetermined viscosity levels and Where they occur are discussed more fully hereinafter.

' It'will be noticed that the aforedescribed system is one which provides for easvcleaning after, any particular the system is one in which the desired pressures can easily be obtained. The temperature Within the container can similarly be easily altered, as will be more fully apparent after the remaining drawings have been described. Referring now to therassociated electrical elements and other parts of theapparatus as shown in FIGURES 4 and 4A:

The transducer 23 converts the mechanical sounds made by the bob 11 striking the upper and lower surfaces 13 and 14 into electrical signals. The transformer 33 serves as an impedance matching device between the transducer 23 and the input of the amplifier circuit. The primary of this transformer is balanced and the center-tap grounded to reduce electrostatic and electromagnetic pickup in the transducer and connecting cable. The transistors 34 and 35, together with their associated components, form a conventional two stageclass A amplifier. Resistors 36 and 37'are. for'bias stabilization and

resistors

38 and 39 are load resistors forthe transistors. Blocking capacitors 40 and 41 are smallenough to attenuate signals lower than the design; frequency center. I Voltage regulator diode 42 and resistor 43 serve to maintain a constant supply voltage. for the two amplifier stages. They also decouple thearnplifier stages from other circuitry.

- ."The combination of'capacitors 44 and 45, resistors 46 and 47, and diode 48 form a rectifier circuit which converts any continuous signal such as mechanical vibrationfelectrical interference or noise into 'a D.C. signal across capacitor 45.. This D.C. signal is blocked from 'the subsequent circuitry by capacitor 49. Capacitor 44 is much larger than capacitor so'that the maximum of any signal at the collector junction 50 of transistor. 35

will appear across capacitor 45. The resultant capacity through .the'base junction by resistor 54 being returned to the supply voltage; The saturation current through the collector of transistor 52 and load resistor 55 cause the voltage at point 56 to be very nearly zero with respect to the common" ground 57. The base of transistor 51 is tied to junction 56 through resistor 58. Therefore very little collector current is flowing through transistor 51-and resistor 59 and the'voltage at the junction 60 of these two is' very nearly equal to the supply voltage 61. Transistor During the cycle of operation-there appears at-junction 56 a rectangular pulse of constant amplitude and constant width. The amplitude is held by maintaining the supply voltage constant with the voltage regulator diode 63 and. resistor 64, and the width is determined by the time constant of capacitor 62 and resistor 54. This rectangular wave form will appear at junction 56 once for every discontinuous signal generated by the transducer when the time interval between signals is greater than the pulse width.

When the rectangular pulse appears at junction 56, it also appears at relay armature contact 65, normally closed relay contact 66 and at the base connection of transistor 67. This causes heavy surge current-to flow through transistor 67, charging capacitor 68, which in turn starts charging capacitor 6? through resistor 70. When the charge across capacitor 69 ha increased sufficiently, enough current will flow through transistor 71 and relaycoil 72 to move the armature contact A to the normally open position 73. The values of

capacitors

63 and 69 and resistor are chosen so that the relay '72 will-not operate until the rectangular pulse at junction 56 has disappeared. The relay willremain closed until the charges on

capacitors

65 and 69 have decreased to the point where insufficient current is flowing through relay 72 and transistor 71 to hold the'armature contact 65 down. The length of time the relay 7?; stays energized can be adjusted by variable resistor 74.

At the same time capacitor 68 is charged, capacitor 75 is charged through diode 76. This causes current to flow through transistor 77 and relay coil 78". There is no delay in energizing relay coil '78. The resistor 7? is for limiting the base current in transistor '77 to a safe value. Relay coil 78 willstay energized for a much longer period than 53 contributes very little to the total current through resister 59 because: the base, connection is not returned to any fixed D.C. reference voltage. V a

. When a.discontinuous signal from the transducer appears at the junction ofcapacitors 45, and 49, it will pass to the base :of transistor 53v causing collector current 'to flow through transistor '53and resistor 59. This causes the voltage at junction 60 to decrease. As the voltage across the capacitor 62 cannot change instantaneously, the voltageat the junction of resistor'54 and the bElSG'COIl,

at junction 60; This action is regenerative and will continue'.until'transistorfsl is saturated and, transistor 52 is cut oil, Thecircuit will' stay in this state'until the charge acrosscapacitor' 62 has been;re ducedby leakage through resistor 54 to the point where transistor 52 can start conductionnAt thispointthe regenerative action is reversed and the circuit is returned to its original stable. state. i

relay coil 72 as the diode 76 has veryhigh back resistance, and variable resistor 74 has no effect on the time constant of capacitor 75 and resistor '79.

If a rectangular. pulse appears at junction 56 during the period when relay coil 72 is energized, it will pass through the relay armature contact 65, through the normally open contact 73 and vto the base connection of transistor 84). This will cause surgecurrent through transistor so to charge capacitor 31 which is connected to the base of transistor 82 through resistor 83, thus causing currentto flow through transistor 82 energizing relay coil 84. The time constants here are essentially the same as those for transistor 77 and relay coil 78.

'If no-rectangular pulse appears at junction 56 during the time that relay coil 72 is energized, relay coil 84 will not become energized; or if relay coil 84 has previ ously been energized and no subsequent pulses appear at unction 56during the time that relay coil 72 is energized, relay'coil 84 will de -energize when the charge across capacitorfil has decreased to a point toolow to maintin suificient current flow through transistor 32. Re-

' lay coil 78 will stay energized so long as any pulses at all nection of transistor 52 decrease, thus decreasing the colappear at junction 56,

Voltage regulator diode 85 and resistor 86 maintain constant supply voltage so that peak charges on

capacitor

68, 75 and 31 will be constant. Capacitor 87 is very large to supply charging currents;

' One wire of the chartdrive motor S8 is connected to the operate switch 89 and the other to the'normally open contact 90 of relay 73. The armature contact 91 is con- .nected to the common side of the power line 92. With.

the operate switch'on and relay 78 energized the chart drive motor will run. Whenjrelay 78 vie-energizes, the

' chart drive motor will stop and indicator lamp 93 will light through relay contact'94. "Also capacitor 95, which is'charged' through rectifier 96 and resistor 97, will be discharged through relay contact 93, 99, 106', 101, and I marker solenoid 192. f The marker solenoid will perforate the time chart'103.

Relay 78 will be energized so lo'ngas any pulses appear at junction 56. Relay$4 will be energized only if pulses ducer 23.

resistors.

Transformer 117,

resistors

112, 113

capacitors

114, 115

and rectifier 116 comprise a half-wave rectifier to furnish power to the transistor circuits. I

Bottom coil 28' is energized through relay contacts 113 and 119. The lighting of neon lamp 120 indicates when the bottom coil is connected in the timing circuit. Timer motor 121 is a 60 cycle 30 rpm. motor which drives a cam 122 directly. Cam 122 in turn moves thecenter arm of microswitch123. Microswitch 123 alternates power once every second to the top coil 27 and to the bottom coil 28 if the bottom coil is in the circuit through relay contacts 118 and 119.

Capacitors 124 and 125 are filter capacitors for the top and bottom coils respectively.

Capacitor 132, resistor 133 and bridge 1341 make up a bridge rectifier circuit to furnish power to the top and bottom coils. 1

Heating elements 26 and a fan 131 are provided in order to heat or cool the pressure cell, these being in the same insulated container as the cell.

Switch 135 which is placed on the face of the insulated chamber is employed to turn the fan 131 on or oil as needed in order to keep the temperature of the vessel as near ason' schedule as possible.

Switch 136, likewise on the face of the insulated cham- Fuse 139 is provided for the top and bottomcoil power supply circuits. Fuse 140, switch 141 and neon lamp indicator 142 are provided for the amplifier circuit. Resistor 143 is an impedance matching resistor for trans- Operation "123. During the other half of the cycle the microswitch 123 is in position to energize the bottom coil 28, but the coil is disconnected through relay 107. Therefore, once every two seconds the bob ll-is lifted and strikes the top 13' of the test chamber. This mechanical sound is picked up by the transducer 23 and an electrical pulse appears at junction 56 as described before. This pulse energizes

relays

72 and 78. Relay 72 stays energized for a period of less-than 2 seconds (approximately 1.85 seconds). One second after the top coil is energized, it is de-energized and the hub falls to the bottom. The pulse from this sound then appears at. junction 56. However,

relay 78 is still energized and the pulse ,travels on to energizerelay 84'. Relays 78 and 84 will stay closed for a period of about 15 to 20 seconds with one pulse to each circuit. However, thebob is being picked upand dropped one-second period during which the top coil is de-ener gized, the above condition will continue. When the cement slurry thickens to the point where the bob will not fall all the way to the bottom and strike the bottom surface before the top coil is energized once more, no pulse will appear at junction 56 when relay 72 is energized and the charge on holding capacitor 81 will start decreasing. After about 15-20 seconds wherein the bob fails to strike the lower surface, relay 84 will de-energize, discharging capacitor 104 through the marker solenoid 162 (which perforates the time chart 103) and energizing relay 107. (In the system being described, this occurs when the cement being tested has reached a viscos ity of about 26 poises.) Relay contacts 119 and 110 then put the bottom coil in the timing circuit. The bob will now be pulled to both top and bottom as the coils are alternately energized. Relay 84 will'again become energized as there is a pulse present at junction 56 during the time relay 72 is energized. Relay 107 will stay be no signal to operate relay 72. However, when the bottom coil is energized, the bob will be pulled back down and the signal from the bob hitting the bottom will operate relay 72. There will then be no signal to keep capacitor 81 charged so that in 15-20 seconds relay 84 will again become de-energized causing the marker solenoid 102 to perforate the chart again. (Inthe system being described this occurs when the cement being tested has reached a viscosity of about poises).

As the samplethickens further, it-will reach a point where the bob is not lifted off the bottom at all and there will be no signal to keep capacitor charged. In 15-20 seconds relay 78 will become de-energized, discharging capacitor 25 through the marker solenoid 102 and perforating the chart. It will also stop the chart motor and light the indicator lamp 93. This is the end of the test although for many purposes it will not be necessary or desirable to carry the test this far.

FIGURE 5 shows a block diagram of the circuit shown in FIGURES 4 and 4A and is set forth by way of explanation of the functions of the electrical components of the system.

Descripti n of Block Diagram 'The 60-cycle'30 r.-p.m. motor 121 drives the cam 122 directly. The cam, in turn, moves the center arm of the microswitch, 123 to its alternate positions once per second. Thus the top coil 27 is energized'once every two seconds for a period of one second by the bridge rectifier 13 This lifts thebob through the slurry sample until it strikes the top of the sample container creating a mechanical signal which is picked up by the transducer 23.

At the end of one second, the cam 122 moves thecenter arm of the microswitch 123 to the opposite position, energizing the bottom coil only if the bottom coillatching relay 107 is energized or the by-pass switch 107A for bot-tom coil 28 is closed, (The by -pass switch'107A is used only when testing slurry samples having an initial consistency too thick to allow the, bob 11 toreach the bottom of the 'container'in a free fall during the onesecond period whenithe top coil 27 is deenergized.)

The fan 131, heaters 26 and heater control 138v are I used as needed to maintain a desired temperature of the slurry sample or to change temperature at a predetermined rate.

coil 27, allowing the bob'to fall.

11 13 of the container 9 is picked up by-the transducer 23, it is fed into the circuitry, as aforedescribed, which make up the parts designated as the amplifier and wave-shaper ofFIGURE and appears at point A as a square wave pulse. This would be at point 56of FIGURE 4. This pulse is passed simultaneously through the relay contacts B and C to the gating circuit and relay and to the holding circuit and relay for the chart motor 88, causing the relay in'the latter circuit to become energized, applying power. to the chart motor and removing power from the end of test indicator lamp 93. One pulse is sufficient to keepthe relay energized and motor 88 running for about lS .seconds. If no additional pulses are received during this time, the relay will de-energize, motor 88 will stop, lamp 93 will come on, and a capacitor will be discharged through marker solenoid .102 punching a hole in the. time chart.

, The gating circuit and relay 72 has av time delay which prevents this relay from 'operating'until after the pulse at point A has disappeared. It then energizes, moving the armature contact B to contact D thus connecting point A with point I of the bottom coil and marker solenoid energizing circuit. This relaywhich is relay 72 of FIG- URE 4 will. stay energized for about 1 /2 seconds allowing sufiicienttimeforthe bob 11 to be released by the top coil 27 'and fall tothe bottom of the container. The square wave created by the sound of the bob 11 striking the bottom now appears at point I of the bottom coil and marker solenoid energizing circuit. This is a holding circuit which prevents the bottom coil-latching relay 107 from operating. If no pulses appear at point I for about seconds, the bottom coil latching relay will energize, connecting the bottom coil 28 to the microswitch'123, and

. a capacitor (95 of FIGURE 4A) Will be discharged through solenoid 102 punching a hole in'the time chart.

The only way the bottom coil latching relay 107 can be deenergized is to turn the operate switch 89 off momentarily; v

A complete testing program consists of the following:

At time zero, the cam 122 operates the microswitch 123, energizing the top coil 27. The bob 11 will be lifted through the slurry sample and at some time betweentime zero and time 1 second (dependent upon the thickness of thesample) the bob'will strike the top of the container and a square-wave will appear at point A. This will cause the chart motor 83 to start running and also initiate the action of the gating circuit relay 72. After the square-wave has disappeared, the gating circuit relay will energize, shifting the armature contact B to contactD. I 'At time l second, the cam moves the microswitch center arm to the opposite position, de-energizing the top When it strikes the bottom of the container, the resultantsquarewave Will appear at point J activating this holding circuit to prevent'the' bottom coil latching relay 107 from operating. 'At time 2 seconds, the top coil is again energized and the entire cycle is repeated.

' a The above sequence is repeated while the operator is changing thetemperature and: pressure in accordance withthe particular schedule being followed until the slurry sample thickens to a point where the bob 11 will no longer fall -to the bottom during the l-second period When-the top coil is off and no pulse will appear at point 7 J duringthe time the gating circuitrelay 72 is energized. Afterflabout 15 secondshave'passed with no pulses appearing 'at point J, the bottom ,coil' latching relay 107 will be energized connecting the bottom coil 28 to the 'microswitch 123 and the solenoid 102 .will punch a hole in the chart. This'represents a slurry sample consistency bob, its size, the strength of the electromagnets, etc.

Now, instead of the bob falling free whenthe top coil is oe-energized, it will be pulled' down by the bottom 1-2 coil .and again there will be pulses present at point A for each position of the gating circuit relay. This will continue until the sample further thickens to a point where the top coil can no longer lift the bob through it in the l-second period the top coil is on. Then there will be no signal from the top to actuate the gating circuit relay, but the next signal from the bottom will do so, and again no pulse will appear at point I. In about 15 seconds, a capacitor will again be discharged through the solenoid 102 punching another hole in the chart. This will occur at approximately 70 poises in the system presently beingv described.

It the test is allowed to continue, the sample will the bob off the bottom and there will be no signals at all.

In about 15 seconds the relay that keeps the chart motor 88 running will de-energize, stopping the motor, turning on lamp 93 and another hole will be punched in the chart. It will, of course, be appreciated that'in testing several materials the test does not have to be carried this far, and that the arrivalat the 70-poise level or thereabouts will convey a suificieiit amount of desired infor' mation about the fluid being tested.

Although I have described my invention in considerable detail, it is understood that the present disclosure has been made only by way of example and that numerous changes in the details of construction and the combination and arrangement of parts, such as, for example, in the use of vacuum tubes rather than transistors, may be resorted to without departing from the'spirit and the scope of the invention as hereinafter claimed.

I claim: I

1. An apparatususeful for measuring the viscosity characteristics of a fluid whose viscosity changes under diiferent pressure and temperature conditions comprising in combination a substantially non-magnetic container for the fluid, electromagnetic windings surrounding upper and lower portions ofa cavity in said container for establishing magnetic fields in said portions of said, container, means having an appreciable viscous drag and being responsive to said fields poistioned within said cavity and freely movable in the fluid, means for intermittentlyand regularly electrically energizing each of said windings whereby said electromagnetically responsive movable means is caused to move into the resultant magnetic fields, surfaces at both the top and bottom of the cavity of said container which generate and transmit sound waves when struck by said movable means, means for converting said sound waves into electrical signals, means for amplifying said electrical signals, electronic means activated by said electrical signals or by the absence thereof and operatively connected to the amplifying means, for sensing variations in the viscosity of the fluid, by said presence or absence of electrical signals, as the viscosity changes from one value to another predetermined value, said sensing means being regulated and operatively connected to the mined viscosity value is reached.

2. An apparatus useful for measuring the viscosity characteristics of a fluid whose viscosity changes under differcut pressure and. temperature conditions comprising in combination a substantially non-magnetic container for the fluid, electromagnetic windings surrounding upper and lowerportions of a cavity in said container for establishing magnetic fields in said portions of said container,

means having an appreciable viscous drag and being responsive to said fields positioned within said cavity and freely movable in the fluid, means for intermittently and regularly electrically energizing each of said windings admin means is caused to move into the resultant magnetic fields, surfaces at both the top and bottom of saidcavity which generate and transmit sound waves when struck by said movable means, means for converting said sound waves into electrical signals, means for amplifying. said electrical signals, means for intermittently energizing only the upper electromagnetic winding when the viscosity of the fluid is low, means for intermittently energizing both the upper and lower windings when the viscosity becomes.

higher, electronic means activated by said electrical signals or by the absence thereof and operatively connected to the foregoing elements andmost particularly-with the signal amplifying means and with the energizing means for the windings for sensing variations in the viscosity of the fluid,- by said presence or absence of electrical signals, as its viscosity changes successively from a low value to a value where the forced gravity alone becomes insuflicient to. cause the movable means to strike the lower surface of the cavity during thetime in the. cycle that the upper winding is de-energized, thence to a value where the force exerted by the. upper winding during'the time in the cycle that it is' energized is insufficient to cause the movable means to strike the upper surface of 'the cavity, and optionally to a value where gravitational force supplemented by the force exertedby the lower winding during the time in the cycle that it is energized becomes insuflicient to cause the movable means to strike the lower surface of the cavity, and means responsive to the said sensing means and operatively connected thereto for recording when the viscosity of the fluid so changes from any'ldwer value to any of said higher values. I

'3-. An apparatus useful for measuring the viscosity characteristics of a fluid Whose viscosity changes under different pressure and temperature conditions compris ing in combination a substantially non-magnetic container for the fluid,.electromagnetic winding means for establishing a'magnetic field in an upper portion of a cavity in said container, means having an appreciable viscous drag and being responsive to said field positioned within said cavity and freely movable in the fluid, means for intermittently and regularly electrically energizing saidwinding whereby said electromagnetically responsive movable means is caused during the time said winding is energized to move into the resultant magnetic field and against a surface in the top portion of said cavity which generates and transmits sound waves when struck by said movable means, a bottom surface in said cavity which also generates and transmits sound waves when struck by said movable means, means for converting said sound waves into electrical signals, means for amplifyingsaid electrical signals, electronic means operatively connected to the amplifying means and activated by the amplified electrical signals'or by the absence thereof for sensing variations in the viscosity of the fluid, by 'saidpresence or absence of electrical signals, as itchangcs from one value to other higher predetermined values and means responsive to the said sensing means and operatively connected thereto for recording when such higher predetermined viscosity values I 5. An apparatus according to clair'n 3 wherein a predetermined viscosity value of the'fluid is reached when the movable means fails to strike the upper surface of, the cavity during the time in the cycle that the upper winding is energized.

6. An apparatus according to claim 3 wherein the as paratus is provided with means for heating the container to any predetermined temperature and with means for recording the temperature of the fluid in the container.

7. An apparatus according to claim 3 wherein the apparatus is provided with means for cooling the container to any predetermined temperature and with means for recording the temperature of the fluid in the container.

8. An apparatus according to claim 3 wherein the apparatus is-provided witnmeans for pressurizing the interior and the contents of the containerand with means for recording the pressure within the'container.

. 9. A process for measuring'the viscosity characteristics of a fluidwhose viscosity changes under different pressure and temperature conditions which comprises: (1)' filling the cavity of asubstantially non-magnetic container with the fluid, which cavity is surrounded at its upper: portion with an electromagnetic winding and which cavity has disposed therein and freely movable in the fluid means having an appreciable viscous drag and which is resp'on sive to said electromagnetic field, and which cavity also possesses surfaces at its top" and bottom which generate and transmit sound waves when struck by said movable means; (2)'interr r1ittently and regularly electrically energiz'ing said winding whereby said electromagnetically responsive movable means is caused to move upwardly into a the resultant upper magnetic field through the fluid toward energizinglthe" upper winding when the viscosity of the the upper surface of said cavity when said winding is energized and, by gravity'when said upper winding is deenergized to'move' downwardly through the fluid toward the lower surface of said container; (3) converting sound waves generated at 'both top and bottom surfaces whenever such surfaces are struck into electrical signals, amplifying same and sending them to an electronic senser which is responsive to said amplified Signals or to the absence of same; (4) controlling the temperature and pressure within said non-magnetic container to simulate conditions which the fluid might encounter; and (5 recording by means of a recorder, which is precalibratcd to measure the viscosity of the fluid'being tested and to do so by being responsive to said electronic senser, when the viscosity of the fluid becomes so greatthat gravitational force becomes insufficient to cause the movable means to strike the lower surface during the time in the cycle that the upper winding is de-energized and also when the electromagnetic force exerted by the upper winding becomes insufficient to cause the'movable means to strike the upper surface during the period in the cycle that the upper winding is energized.

10. A process for measuring the viscosity characteristics of a fluid whose viscosity changes under different pres sure and temperature conditions which comprises: 1) filling the cavity of a substantially non-magnetic container with the fluid, which cavity is surrounded at its upper and lower portions with electromagnetic windings and which cavity has disposed'therein and freely movable in the fluid means having an appreciable viscous drag and which is responsive to said electromagnetic fields, and which cavity also possesses surfaces at itstop and bottom which gen erate and transmit sound waves when struck by said movable means}(2)iintermittently'and regularly electrically fluidis low whereby said electro'magnetically responsive movable means is caused to nrove upwardly into the resultant uppermagnetic field through the fluid toward the upper surface of said cavity when said windingis' energized and', b y gravity, when said upper winding is deenergized, to move downwardly through the fluid toward the lower surface of said containers; (3) additionally intermittently 7 and regularly electrically energizing the lower winding whenth'evis'cosity of the fluid, becomes so high as to prevent the movable" means'from striking the lower surface by the mere'force ofgravity alone during the time portion "er cycle that the upper winding is de-energized; (4) converting the; sounds generated at both top and bottom stir-magma electrical signals, amplifying same and sendingthem to an electronic sens'cr WhiChiS responsive'to said amplified signals or to the absence of same; (5) controlling thetemperature and pressure within saidnonby theuiiper winding becomes insuflicient to cause the. movable means to strike the upper surface during the I period in the cycle that the upper winding is energized;

and optionally when gravitational force plus the electroa magnetic force exerted by the lower winding are together insufiicient'to cause the movable means to strike the-lower surface during the periodin the cycle that the lower winding is energized.

11. An apparatus useful for measuring viscosity charracteristics of a fluid whose viscosity changes under different pressure and-temperature conditions comprising in combination: (1) a substantially non-magnetic vpressure cell for the fluid, internally threaded near its top; (2) electromagnetic windin'g ineans for establishing a magflanged at its base and externally threaded at its upper portion, also possessing a hollow cylindrical bore and" adapted for close proximate insertion through the hollow cylindrical bore of said closure (7) a resilient sealing gasket surroundingsaid inlet stem and situated between the flange of said stem and the base of said closure 5;

netic field insaid cell; (3) means having an appreciable r viscous drag and being responsive to said field positioned within said cell and freely movable in the fluid; (4) means for intermittently and regularly electricallyrenergizing said I winding whereby said electromagnetically responsive movable. means is caused to move into the resultant magnetic field; (5) a closure possessing a hollow cylindrical bore adapted to be threaded into said cell; (6) a cylindrical inlet stem flanged at its base and externally threaded atits upper portion, also possessing ahollow cylindrical bore and adapted for, close proximate insertion through the hollow cylindrical bore ofsaid closure 5; (7) a resillent sealing gasket surrounding said inlet -stein and situated between the flange of said stem and the base of said closure 5; .(8) a pressure seal nut adapted to be threaded about said inlet stern and to cause the flange of said stern to'pressure the sealing gasket against the bottom of said elesure'; (9) a valve body threaded onto the top of said inlet stem and forming a pressure-tight seal therewith; (10) pressure input means in said valve body communicating with the hollow cylindrical bore of said inlet stem;

(11) a thermowell packing bolt threaded into said valve body forming a pressure-tight seal therewith and having a hollow cylindrical bore therein; (12) a thermowell projecting through said packing bolt, said valve body and said inlet stem into'said pressure cell; (13) means, opera- 'tively connected to the movement of the viscous drag means caused by the electromagnetic winding, for sensing variations in the viscosity of the fluid as it changes from one value'toother values; and (14) means responsive to'the said sensing means and operatively connected thereto for recording said varied viscosities. 7

12. An apparatus useful for measuring viscosity characteristics of a fluid whose viscosity changes under different pressure'andtemperature conditions comprising in combination: (1) a substantially non-magnetic pressure cell for the fluid, I internally. threaded .near' its top;

, electromagnetic ,winding' means for-establishing a magnetic field in said cell; (3) meanshaving'an appreciable viscous drag and being responsiveto saidfield positioned within said cell and freely movable in the fluid; (4)

means for intermittently and regularly electrically energizing saidwinding whereby said electromagnetically responsivc movable means is caused to'move into the resultant vmagnetic field and toward a surface in the top portion of said cell ;which generates and transmits sound waves-when struck by said movable means and "by gravity when said winding is not energized toward a bottom (8) a pressure seal nut adapted to be threaded about said in'let stem and to cause the flange of said stem to ,(10) pressure input means in said valve body communi-' eating with the hollow cylindrical bore of said inlet stem; (11) a thermowell packing bolt threaded into'said valve body, forming'a pressure-tight seal therewith and having.

a hollow cylindrical bore therein; 12) a thermowell projecting through said packing bolt, said valve body and said inlet stern into said pressure cell; (13) means for converting the sound waves caused by the impact of the magnetically responsive means 3- against the top and bottomsurfaces of said cell into electrical signals; (14) means for amplifying said electrical signals; (15) electronic means operatively connected to amplifying means and activated by the amplified electrical signalsor by the absence thereof for sensing variations in the viscosity of the fluid, by said presence or absence of electrical sig nals', as itchanges from one value to other values; and (16) means responsive to the said sensing means and operatively connected thereto for recording said varied viscosities.

13. An apparatus useful for measuring viscosity characteristics of a fluid whose viscosity changes under difiere ent pressure and temperature conditions comprising in combination: (1) a substantially non-magnetic pressure able viscous drag and being responsive to said fields positioned within said cell and freely movable in the fluid;- (4) means for intermittently and regularly electrically energizing each ofsaid windings whereby said electromagnetically responsive movable means is caused to move. into the resultant magnetic fields and toward surfaces in the top and bottom portions of said cell which generate and transmit sound waves when struck by said movable means; (5) a closure possessing a hollow cylindrical bore adapted to be threaded into said cell; (6) a cylindrical inlet stern flanged at its base and externally threaded at its upper portion, also possessing a hollow cylindrical bore and adapted for close proximate insertion through the hollow cylindrical bore of said closure 5; (7) a resilient sealing gasket surrounding said inlet stern and situated between the flange of'said stem and the base of said closure 5; (8) a pressure seal nut adapted to be threaded about said inlet stem and to cause the flange of said stem to pressure the sealing gasket against the bottom of said closure; (9) a valve body threaded onto the top of said inlet stem and forming a pressure-tight seal therewith; (l0) pressure input means in said 'valve body communir eating with the hollow cylindrical bore of said-inlet stem; 7

(1 1) aithermowell packing boltthreaded into said valve body, forming a pressure-tight seal therewith andlhaving V convertingthesoundtwaves caused by the impact ofthe surface in said cell which also generates and transmits sound waves when struck by said movable means; (5) a closure possessing a hollow cylindrical bore adapted torbe threaded into said cell; (6) a cylindrical; inlet stem magnetically responsive'means 3 against the top and bottom surfaces of said cellinto electrical signals; (14) means for amplifying said electrical signals; (15) eleotronic means operatively connected to the amplifying means and activated by the amplified electrical signals or by the absence thereof for sensing variations in the viscosity of the fluid, by said presence or absence of electrical signals, as it changes from one value to other values;

17 and (16) means responsive to the said sensing means and operatively connected thereto for recording said varied viscosities. V a

14. An apparatus useful for measuring viscosity characteristics of a fluid whose viscosity changes under different pressure and temperature conditions comprising in combination: (1) a substantially non-magnetic pressure cell for the fluid, internally threaded near its top; (2) electromagnetic windings surrounding upper and lower portions of said cell for establishing magnetic fields in said portions of said cell; (3) means having an appreciable viscous drag and being responsive to said field positioned within said cell and freely movable in the fluid; (4) means for intermittently and regularly electrically energizing each of said windings whereby said electromagnetically responsive movable means is caused to move into the resultant magnetic field and toward surfaces in the top and bottom portions of said cell which generate and transmit sound waves when struck by said movable means; (5) -a closure possessing a hollow cylindrical bore adapted to be threaded into said cell; (6) a cylindrical inlet stem flanged at its base and externally threaded at its upper portion, also possessing a hollow cylindrical bore and adapted for close proximate insertion through the hollow cylindrical bore of said closure 5; (7) a resilient sealing gasket surrounding said inlet stern and situated between the flange of said stern and the base of said closure 5; (8) a pressure seal nut adapted to be threaded about said inlet stem and to cause the flange of said stem to pressure the sealing gasket against the bottom of said closure; (9) a valve body threaded onto the top of said inlet stem and forming a pressure-tight seal therewith; (10) pressure input means in said valve body communicating with the hollow cylindrical bore of said inlet stem; (11) a thermowall packing bolt threaded into said valve body, forming a pressure-tight seal therewith and having a hollow cylindrical bore therein; (12) a thermowall projecting through said packing bolt, said valve body and said inlet stem into said pressure cell; (13) means for converting the sound waves caused by the impact of the magnetically responsive means 3 against the top and bottom surfaces of said cell into electrical signals; (14) means for amplifying said electrical signals; (15) electronic means operatively connected to the amplifying means and activated by the amplified electrical signals or by the absence thereof for sensing variations in the viscosity of the fluid, by said presence or absence of electrical signals, as it changes from one value to another predetermined value; (16) means operatively connected to said sensing means for intermittently energizing only the upper electromagnetic winding when the viscosity of the fluid is low; (17) means also operatively connected to said sensing means for intermittently energizing both the upper and lower windings when the viscosity reaches a predetermined higher value; and (18) means responsive to the said sensing means and operatively connected thereto for recording said varied viscosities.

15. An apparatus useful for measuring the viscosity characteristics of a fluid whose viscosity changes under different pressure and temperature conditions comprising in combination a substantially non-magnetic container for the fluid; electromagnetic winding means for establishing a magnetic field in an upper portion of a cavity in said container; means having an appreciable viscous drag and being responsive to said field positioned within said cavity and freely movable in the fluid; means for intermittently and regularly electrically energizing said winding whereby said electromagnetically responsive movable means is caused during the time said winding is energized to move into the resultant magnetic field and against a surface in the top portion of said cavity which generates and transmits sound waves when struck by said movable means; means for converting said sound waves into electrical signals; means for amplifying said r a t I 18 electrical signals; electronic means operatively connected to the amplifying means and activated by the amplified electrical signals or by the absence thereoffor sensing variations in ,theviscosity of the fluid, by said presence or absence of electrical signals, as it changes from one value to other values; and means responsive to the fore-. going sensing means and operatively connected thereto for recording said varying viscosities.

16. An apparatus useful for measuring viscosity characteristics of a fluid whose viscosity changes under different pressure and temperature conditions comprising a substantially non-magnetic pressure cell for the fluid, internally threaded near its top; electromagnetic winding means for establishing a magnetic field in said cell;-

a bob having an appreciable viscous drag and being responsive to said field positioned within said cell and freely movable in the fluid; means for intermittently and regularly electrically energizing said winding whereby said electromagnetically responsive movable bob is caused to move into the resultant magnetic field; a closure possessing a hollow cylindrical bore adapted to be threaded into said cell; a cylindrical inlet stem flanged at its base and'externally threaded at its upper portion, also possessing a hollow cylindrical bore and adapted for close proximate insertion through the hollow cylindrical bore of said closure; a resilient sealing gasket surrounding said inlet stem and situated between the flange of said stern and the base of said closure; a pressure seal nut adapted to be threaded about said inlet stem and to cause the flange of said stem to pressure the sealing gasket against the bottom of said closure; a valve body threaded onto the top of said inlet stem and forming a pressuretight seal therewith; pressure input means in said valve body communicating with the hollow cylindrical bore of said inlet stem; a thermowall packing bolt threaded into said valve body forming a pressure-tight seal therewith and having a hollow cylindrical bore therein; a thermowell projecting through said packing bolt, said valve body and said inlet stem into said pressure cell; a surface at the top of the cavity of said container which generates and transmits sound waves when struck by said bob; means for converting said sound waves into electrical signals; means for amplifying said electrical signals; electronic means operatively connected to the amplifying means and activated by the amplified electrical signals or by the absence thereof for sensing variations in the viscosity of the fluid, by said presence or absence of electrical signals, as it changes from one value to other values; and means responsive to the foregoing sensing means and operatively connected thereto for recording said varying v1scos1t1es.

17. A process for measuaring the viscosity characteristics of a fluid whose viscosity changes under dilferent pressure and temperature conditions which comprises: (1) filling the cavity of a substantially non-magnetic container with the fluid, which cavity is surrounded at an upper portion with an electro-magnetic winding means for establishing a magnetic field in said upper portion of the cavity, which cavity, has disposed therein and freely movable in the fluid a bob having an appreciable viscous drag and which is responsive to said electromagnetic field, and which cavity also possesses a surface at its top which gencrates and transmits sound waves when struck by said movable bob; (2) intermittently and regularly electrically energizing said winding whereby said electromagnetically responsive movable bob is caused during the time said winding is energized to move upwardly into the resultant magnetic field and against said surface in the top portion of said cavity which generates and transmits sound waves when struck by said movable bob; (3) converting said sound waves into electrical signals; (4) amplifying said electrical signals; (5) sending said amplified signals to an electronic senser which is responsive to said amplified signals or to the absence of same and which also senses variations in the viscosity of the fluid, by said presence 19 or absence of electrical signals, as it changes from one value to other values; (6) controlling the temperature and pressure within said non-magnetic container to simulate conditions which'the fluid might encounter; and -(7) recording said varying viscosities by recorder means responsive to said sensing means and operatively connected thereto.

References Cited in the file of this patent UNITED STATES PATENTS

Claims

1. AN APPARATUS USEFUL FOR MEASURING THE VISCOSITY CHARACTERISTICS OF A FLUID WHOSE VISCOSITY CHANGES UNDER DIFFERENT PRESSURE AND TEMPERATURE CONDITIONS COMPRISING IN COMBINATION A SUBSTANTIALLY NON-MAGNETIC CONTAINER FOR THE FLUID, ELECTROMAGNETIC WINDINGS SURROUNDING UPPER AND LOWER PORTIONS OF A CAVITY IN SAID CONTAINER FOR ESTABLISHING MAGNETIC FIELDS IN SAID PORTIONS OF SAID CONTAINER, MEANS HAVING AN APPRECIABLE VISCOUS DRAG AND BEING RESPONSIVE TO SAID FIELDS POSITIONED WITHIN SAID CAVITY AND FREELY MOVABLE IN THE FLUID, MEANS FOR INTERMITTENTLY AND REGULARLY ELECTRICALLY ENERGIZING EACH OF SAID WINDINGS WHEREBY SAID ELECTROMAGNETICALLY RESPONSIVE MOVABLE MEANS IS CAUSED TO MOVE INTO THE RESULTANT MAGNETIC FIELDS SURFACES AT BOTH THE TOP AND BOTTOM OF THE CAVITY OF SAID CONTAINER WHICH GENERATE AND TRANSMIT SOUND WAVES WHEN STRUCK BY SAID MOVABLE MEANS, MEANS FOR CONVERTING SAID SOUND WAVES INTO ELECTRICAL SIGNALS, MEANS FOR AMPLIFYING SAID ELECTRICAL SIGNALS, ELECTRONIC MEANS ACTIVATED BY SAID ELECTRICAL SIGNALS OR BY THE ABSENCE THEREOF AND OPERATIVELY CONNECTED TO THE AMPLIFYING MEANS, FOR SENSING VARIATIONS IN THE VISCOSITY OF THE FLUID, BY SAID PRESENCE OR ABSENCE OF ELECTRICAL SIGNALS, AS THE VISCOSITY CHANGES FROM ONE VALUE TO ANOTHER PREDETERMINED VALUE, SAID SENSING MEANS BEING REGULATED AND OPERATIVELY CONNECTED TO THE INTERMITTENTLY ENERGIZING MEANS SO THAT ONLY THE UPPER ELECTROMAGNETIC WINDING IS INTERMITTENTLY ENERGIZED WHEN THE VISCOSITY OF THE FLUID IS LOW, AND BOTH THE UPPER AND LOWER WINDINGS ARE INTERMITTENTLY ENERGIZED WHEN THE VISCOSITY REACHES A PREDETERMINED HIGHER VALUE, AND MEANS RESPONSIVE TO THE SAID SENSING MEANS AND OPERATIVELY CONNECTED THERETO FOR RECORDING WHEN THE HIGHER PREDETERMINED VISCOSITY VALUE IS REACHED.