US3041871A - Viscosimeter - Google Patents

Description

July 3, 1962 H. J. LBLlcH 3,041,871

vIscosIMETER Filed July 19, 1957 HANS J. LOBLICH ATTORhEY atomizer.

vobtained from a variety of suppliers.

United States Patent 3,041,871 VISCOSIMETER Hans J. Loblich, Isestrasse 49, Hamburg 13, Germany Filed July 19, 1957, Ser. No. 672,972 6 Claims. (Cl. 73-57) The invention is a dev-ice designedior measuring viscosities or, among others, for determining values apt to change the viscosity, specially for determining temperatures to be reached by preheating in order to bring the viscosity of heavy fuel oils, .for instance, to a suitable pointr of atomization.

Fuel oils, particularly in industrial burner installations, must be sprayed into the tiring chamber with the aid of atomizers as finely distributed as possible in order to burn. The air required for the burning process is fed into the chamber simultaneously. In this connection care is taken that the two substances mix as thoroughly and rapidly as possible so that each fuel particle is surrounded with sufficient air to burn. Good atomization is a preliminary condition for good combustion, and gi od combustion again is a preliminary condition for economic operation.

How well the fuel oil is atomized by means of a given atomizer depends, among others, primarily on the viscosity at which a ygiven fuel oil is fed to the nozzle of the If the fuel oil is too viscous in comparison to the values for which the installation has been adjusted, it will be impossible to reach optimum atomization or combustion and, therefore, optimum economics.

Burner manufacturers set up specifications to indicate the most favorable atomizer viscosity which varies for the ydifferent nozzles but are very specific for each individual type. The most favorable fuel oil viscosity to be reached in front of the nozzle as recommended for one type 'of atomizer, for instance, is 2.5 E and for another E. Also other viscosities are specified.

The Viscosity of a fuel oil, as is generally known, may be reduced by corresponding preheating. A specific viscosity, however, cannot usually be guaranteed by the fuel oil suppliers. Diiferences in viscosities must be expected to a greater or lesser extent, moreover, if `fuel oils are For industrial enterprises using fuel oil it is of greatest importance to know lthe actual viscosity behaviour of the fuel oil concerned and specially of the blend contained in a fuel oil storage tank after receipt of each new delivery. Trained personnel can determine the temperature to which the fuel oil must be pre-heated in order to obtain the most favorable viscosity for atomization by consulting curve-charts' and/ orV plant is rarely computed and made known Ito the operators. Such determinations are even less frequently made of blends actually present in the storage tank.l

The Stoker or foreman tending the installation usually relies on his so-called experience; either he adjusts vthe temperature to which the fuel oil is preheated by intuition or not at all. This accounts for the fact most likely to lprevail that optimum conditions do not exist with the atomizers. Either the fuel oil is too viscous-in that case atomization and eiciency of the instllation are below optimum--or else the personnel, to be safe, heats testing.

up lthe fuel oil too much which may produce the same results, quite apart from a Waste of steam or electricity due to the practice of preheating the fuel oil excessively. In both cause the costs are higher .than necessary.

Example-For every ton of fuel oil preheated 20 C. in excess 44.092 lbs. of steam are consumed. Based on a steam price of $2.50 per ton the unnecessary excess expenditure amounts to $50.0() on every 1000 tons of fuel oil.

On the other hand, every percent by which efficiency is reduced due to insufficient atomization will result in a loss of about $0.30 per ton of fuel oil. Based on a consumption of 1000 tons of fuel oil, the loss amounts to $300.00.

This invention is intended to remedy the situation by making an easily operated device available to the personnel of industrial .burner installations by which the temperature to which the fuel oil or fuel oil blend should be preheated may be determined instantly and directly at any time Without need of conversion and without resort to tables, charts or other aids except the described appliance itself.

Examples of the viscosimeter in accordance with invention are shown on `the attached diagram.

FlG. 1 shows the front view of a viscosimeter.

FIG. 2 shows the side view of the viscosimeter of FIG. l, partly a sectional view.

FlG. 3 shows a modified version of a timing device.

FIG, 4 shows a different design for actuating or arresting the plunger stem (piston shaft) of the viscosimeter.

The apparatus consists of a container 1 fitted with a detachable bottom part la for easier cleaning, and of a plunger 2 fwith plunger stern 3, freely movable inside the container. 'Ihe plunger stem 3, cross section, is squareshaped.

Either one, several or all faces of the plunger stem are provided with graduated scales indicating temperature and/or viscosity degrees. The drawing shows temperature scales designed to indicate the temperature to which the `fuel oil tested must be preheated in order to reach the viscosity marked on the stern -above the scale. The scales may show temperature readings for viscosities of 2.5 E, 3 E, 4 E and 5 E. The scales may also be calibrated in other viscosity units or with pictorial symbols showing a pressure atomizer, for example, or corresponding words.

Container 1 is closed by a cover, e.g. by a screw-top, through which plunger stem 3 moves up or down. The plunger stem may be arrested in any position by a brake actuated by means of a timing device 12.

The timing device 12 is an all-enclosed tube 5 filled with oil 10 and in addition holding a metal ball 11. This metal ball has a smaller diameter than tube 5 sothat it may sink through the oil by its own gravity whenever the opposite end of tube 5 is in the lower position. Oil 1t) should possibly have the same viscosity index as the fuel oil 13 which is to be filled into the container 1 for In other words, the viscosity temperature curve plotted on a logarithmic diagram should run as closely parallel Vto the corresponding curve of the fuel oil under the ` investigation as possible.

Brake 7 is actuated by the oil-filled timing' device through a wedge-shaped slide mechanism 8 in the following manner. Turning the timing device 12 from its position shown on the drawing clockwise around its pivot plunger stem 3, thus releasing said stem. The timingV device 12 is rotated clockwise through nearly 180 or until stop rest 6a has driven wedge-shaped slide mechanism 8 completely down and is resting thereon. Stop rest 6a resting on slide mechanism 8 prevents the timing device 12 from rotating further in a clockwise direction and holds it in this position while the timing device completes its timing function; after the timing device completed its timing function, i.e. after the metal ball 11 sinks to the point of reversal (that point at which the weight of the sinking metal ball causes the timing `device to rotate in a counterclockwise direction), the timing device will swing around in a counterclockwise direction, until the stop rest 6b acts upon the lower edge of the wedge-shaped slide mechanism 8 driving said wedgeshaped slide mechanism in an upwardly direction so as to remove the wedge and free the brake 7 (and springloaded pin 14) to move perpendicularly toward the plunger stem 3 until it contacts and breaks the fall of the plunger stem. The latter applies brake 7 which in turn blocks plunger stem 3 in the position to which it has dropped.

Brake 7i may be designed to form a spring-loaded pin 14 which presses against the plunger stem 3 and is lifted from the plunger stem through the wedgeshaped slide mechanism 8 which in turn is actuated as shown by timing device 12, thus releasing the plunger stem.

The timing device 12 has two hammering surfaces represented in FIGURES 1 and 2 as 6a and 6b. These two surfaces are so situated that as the timing device 12 is rotated clockwise (by hand to start the timing sequence), the surface (or rest stop) 6a will contact the upper face of Wedge-shaped slide mechanism 8, driving said wedge-shaped slide downward between the Wall of the cover 4 and the head of the spring-loaded pin 14 (represented in FIGURE l, as 7). As the Wedge is driven between the cover and head of the pin, the pin is forced outwardly in a plane perpendicular to that of the plunger stem 3, freeing the pin from contact with the plunger stem and allowing the plunger to fall freely through the liquid in the container. At the sam-e time that the timing device 12 is rotated clockwise by hand to strike wedge 8 freeing the plunger stem, the timing device is placed in such a position as to commence the timing of the fall of the plunger. ,This is accomplished automatically since the rotation in a clockwise direction also places the metal ball 11 in such a position as to fall freely through the liquid 10 within the inverted enclosed tube 5. As the metal ball 11 completes its fall through the liquid in the tube, its weight will cause the timing device to rotate in a counterclockwise direction until the second hammering face or rest stop 6b strikes the bottom face of Wedge-shaped slide mechanism 8. The force of 6b striking upon the lower surface of 8 will drive the wedge from between the Wall of the cover 4 and the head of the spring-loaded pin 1'4. As the wedge is driven from between the wall of the cover and the head of the pin, the tension on the spring will drive the pin inwardly in a plane perpendicular to the plunger stern until said pin contacts and halts the free falling plunger by friction. Thus, the timing device 12 starts and stops the fall of the plunger in the container at the beginning and end of a timed sequence (i.e. the time required for the metal ball to fall through the liquid in the enclosed tube).

The testing procedure is as follows: Remove cover 4 together with plunger 2 and plunger stem 3, ll container 1 with the fuel oil to be tested up to the mark 9 and pull out plunger stem 3 as far as it will go. Just outside the cover the zero mark on the stem will show. The timing device is hanging down, this causes the brake 7 to be in braking position and keeps plunger stem 3 in zero position. Then screw the cover back on the container with plunger stem and plunger pulled up, and

place the apparatus on a horizontal surface. Wait until the entire system, especially the fuel oil under test and the oil in the timing device 12 have the same temperature. Whether that temperature is high or low is of no great importance but possibly it should be between 15 and 35 C. Now take brake 7 out of its braking position. This is done by swinging the timing device around quickly in clockwise direction, which causes the wedge-shaped slide mechanism 8 to retract the brake. The best way to do this is by moving the timing device with one hand while the other holds the device. Ball 11 will now sink towards the bottom inside the timing device 12 and after a while it reaches a point Where its weight causes it to swing around its pivot pin. 'Ihe timing device knocks against the slide mechanism 8 and moves it in such a way that it releases brake 7 which then stops the plunger stem 3.

The reading of the temperature to which the tested fuel oil must be preheated to reach the viscosity required for atomization as shown on top of the corresponding scale can now immediately be taken directly from the scale on plunger stern 3. The latter is then pulled out and cleaned of the fuel oil. Measuring is repeated several times to verify the results. If they deviate it may assumed that the temperature of the oil in the timing device and of the tested fuel oil are not yet entirely identical. Care must be taken that ball 11 prior to each measurement taken has resumed its lower starting position. In case that measurements are taken aboard ship the apparatus should be suspended from a gimbal. In that way accuracy of the measurements will not be affected by the movement of the ship.

The test apparatus works on the generally known principle that the friction resistance of a liquid in a laminar How range is proportional to the viscosity of that liquid.

In the case presented the distance traversed by the sinking plunger 2 and plunger stem 3 within a certain time, e.g. within 20 seconds, through the fuel oil being tested is directly proportional to the viscosity of fuel oil 13. On the other hand the viscosity of the fuel oil 13 at room temperature determines the degree to which it must be preheated to reach a definite lower viscosity for atomization. For that reason the plunger stern should be calibrated not only in units of the distance it traverses within the unit of time, e.g. in millimeters per second nor only in viscosity units computed on that basis, but it should be calibrated rather directly in temperature degrees required for preheating to reach a definite viscosity for atomization. A separate scale is wanted for every desired viscosity.

In order to make the measurements with the described test apparatus independent of a special stop watch and a definite temperature, an oil-filled timing device coupled to the test oil container has been used for measuring theV time. The oilfilled timing device is adjusted in such a way that it allows the plunger 2 with plunger stem 3 (at a temperature of the entire system of 25 C., for instance, and at a certain viscosity of the oil 10i) exactly 20 seconds to drop before it stops the plunger automatically as it becomes top-heavy and swings around. If the temperature of the system is lower than 25 C., both the ball in the timing device and the plunger 2 in the fuel oil sample 13, will require more time to drop since both the oil 10 and the tested fuel oil 13 have the same viscosity index so that the test results will be the same. The same applies if the temperature of the system is higher than 25 C. The time for the process will then be shorter.

The viscosimeter according to the invention assures the accuracy of the measurement results to be independent of the temperature of the system. This is accomplished by the fact that ata higher temperature of the system, for example, not only the plunger with the lplunger stem but also and to the Asame extent the ballof .the liquid-.filled timing device will sink at a faster rate, causing the brake to be actuated atan earlier time through correspondingly earlier swing action by the timing device so long as the viscosity of the liquid in the timing device and that of the liquid to be tested react the same to temperature. This assures correct and .identical results to be obtained the same as,at lower temperatures of the system. This applies analogously also to lower temperatures.

The test apparatus may also be used strictly for measuring viscosity. For that purpose one or several scales will bemarked on Athe -plunger stern. One such scale'may be calibrated, for-instance, in Jviscosity units, as for example in E, cst. etc. I-he scale must-be calibrated in such a way that a viscositycorresponding exactly to the viscosity of the tested fuel oil is indicated on it after a certain test period. t

The test procedure is as follows: Fill the liquid to be tested into the container, screw the cover on the container with plunger stern fully pulled out, release the brake while starting a stop watch at the same time, stop the plunger with plunger stem at the end of the test period, c g. after 20 seconds, by applying the brake and take readings of the viscosity from the markings on the plunger stem and of the temperature of the oil being tested. For this purpose a thermometer is to be provided that dips into the oil inside the container and from which readings can be taken possibly from the outside.

In this manner the viscosity of the tested liquid at a certain temperature, i.e. at the test temperature, may be determined. Next the temperature of the contents of the container may also be changed and the measuring repeated. This will provide a second viscosity value at a different temperature. The procedure makes it possible as in the case of mineral 4oil products, for instance, to enter these points on a special temperature viscosity sheet (eg. of Ubbelohde) and to determine the complete viscosity-temperature curve of the mineral oil product concerned.

The plunger stem may also be calibrated in other units as for example in millimeters, centimeters etc. and 4the conversion into viscosity units may be done with the aid of special tables as follows: if the plunger at the end of a test period of 20 seconds, for instance, sank l5 millimeters the viscosity of the liquid being tested is x E. If, on the other hand, the plunger sank 40 millimeters the viscosity of the liquid is lower and corresponds to y E, etc.

In place of a special stop watch an oil-filled timing device according to the above description may also be used. The exact time for the timing device to complete its cycle of operations at one or several temperatures may be known so that the oil-filled timing device may be used in place of a special time recording piece, providing the temperature concerned is maintained.

According to the invention a time piece may generally be used designed on the principle of the oil-filled timing device as described above but filled with a liquid the viscosity of which does not change with its temperature as for instance with water so that a period of uniform duration is assured in each case for taking the measurements.

More to the purpose would be, however, to build the viscosimeter in such a way that a timing device filled with water (preferably for direct viscosity determinations) and one filled with oil may be used optionally, in the latter case filled with oils of different viscosity indices (eg. for determining temperatures to which heavy fuel oils must be preheated or for analysing used lubricating oils for diluting etc.), the twoftiming devices to be coupled to the apparatus interchangeably.

`According to one design a drop 23 may be built into the timing device (FIG. 3), one edge of which must be of a size and slant'so that ball 11 can start on its path downwards only after the timing device actually has been turned around far enough to assure the release of brake 7. This will prevent errors from occurring as a result of the timing device having been turned around too slowly so that the ball starts on its course before the plunger does.

Apart from the described ycoupling of the plunger brake with a timing device'there are other solutions for accomplishing the purposes of the invention.

As shown in FIG. 4 timing device 12 lifts an arrester 20 as it is rotated in a clockwise direction so that plunger stem 3 is released. As soon as the timing device has become top-heavy (i.e., the weight of the sinking ball has caused the timing device to rotate in a counterclockwise direction) the arrester 20 resumes its function'. In this design the plunger stern is suitably knurled 21 or notched and the timing device is equipped with a stop restsimilar to 6b which will come in contact with the cover 4 of FIGURE l and hold the timing device in the position illustrated by the dotted lines of FIGURE 4 until the metal ball has fallen to the point of reversal.

I claim:

1. A viscosimeter, comprising a container fo-r a liquid to be tested; ia cover for said container defining an orifice located concentrically therein; a plunger, including a calibrated shaft portion fitted in said orifice for slidable movement reciprocally therethrough, and a head portion fit-ted in said container in diametric, radially spaced, relation thereto, and for reciprocal movement longitudinally thereof; a plunger brake mounted on said cap, said brake being disposed for movement into engagement with said plunger shaft portion whereby to restrain downward movement thereof through said orifice; and means, including a liquid-friction timing device rotatably mounted on `said cap, adapted alternately to disengage and to engage fsaid plunger brake with said shaft to permit determination of the downward movement of said plunger by means of the calibrated sha-ft portion thereof in a timed sequence.

2. A viscosimeter according to claim 1, wherein said plunger shaft portion includes a laterally notched side surface area extending longitudinally of said shaft, and wherein said plunger brake comprises a pawl pivotally mounted on said cap for arcuate movement in a pl-ane at righ-t angles to said shaft notched surface area to disengage and to engage said pawl with said surface portion.

3. A viscosimeter according to claim l, wherein said plunger brake comprises a pin mounted radially of said cap in perpendicular relation to said plunger shaft, said pin having an inner end, and an outer end having a headed portion; spring means engaged between s-aid cap and said pin whereby to bias `said pin for engagement of said pin inner end with said plunger shaft, Iand a cam slide adapted for slidable engagement with said pin outer end headed portion, said slide moveable by said timing device to disengage and to engage said pin inner end with said plunger shaft.

4. A viscosimeter according to claim 3, wherein said cam slide is an elongated element having obversepand reverse surface portions and defines a passageway opening through said surface portions, said passageway adapted to receive said Vpin outer end for movement of said slide diametrically of said pin; a cam `surf-ace conto-ur deiined in said slide obverse surface portion; said slide disposed for slidable engagement between said pin headed portion and said cam surface contour, and between said slide reverse surface portion land said cap.

5. A viscosimeter according to claim l, wherein said liquid-friction timing device comprises -a hollow, cylindrical container tube adapted. to be filled with a liquid material, said tube having top and bottom ends; a ball weight disposed in said tube, said ball being fitted to said tube in relatively close radially spaced relation to said tube inner wall, land adapted for movement from one end of said tube to the other by gravity while under restraint of liquid-friction between a tube contained liquid and the surface of said ball; a tube holder pivotally mounted on said cap, said holder adapted to receive and secure said tube for limited arcuate rotational movement in a path common to a plane through said tube longitudinal axis and parallel to a surface of said plunger shaft, wherein said tube is disposed in said holder in a relation to said holder pivotal mount such that movement of said ball weight from the bottom end of said tube to the top end thereof will produce Arotation of said holder in 4said arcuate path about said mount, and wherein said holder is adapted to disengage said brake means at one end of its arcuate path of movement and to reengage said brake means at the other end of said path.

6. A viscosimeter according to claim 5, wherein said container tube includes an internal stop for said ball weight, adapted to retain said weight in the bottom end of said tube during arcuate rotational movement of said References Cited in the file of this patent UNITED STATES PATENTS 989,822 Strasburger Apr. 18, 1911 1,225,438 Howard May 8, 1917 2,234,437 Kistler Mar. ll, 1941 2,699,540 Hunter 1--- Jan. ll, 1955

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