Brookfield KF40 Operating Instructions Manual

Download

Page 1

BROOKFIELD KF40

Falling Ball Viscometer

Operating Instructions

Manual No. M19-354

INSTRUMENTATION & SPECIALTY CONTROLS DIVISION

11 Commerce Boulevard, Middleboro, MA 02302 USA

Tel: 508-946-6200 or 800-628-8139 (USA excluding MA) Fax: 508-946-6262 Internet http://www.brookfieldengineering.com

Page 2

Page 3

Table of Contents

I. INTRODUCTION ..................................................................................................5

I.1 Components....................................................................................................................................................5

I.2 Specications ..................................................................................................................................................6

I.3 Details on Viscosity Measurement Range ............................................................................................7

I.4 Description of the Equipment ..................................................................................................................7

I.5 Safety Symbols and Precautions ...........................................................................................................10

I.6 Cleaning ......................................................................................................................................................... 10

II. GETTING STARTED ............................................................................................11

II.1 Choice of Balls .............................................................................................................................................. 11

II.2 Filling the Sample Tube ............................................................................................................................ 11

II.3 Temperature Control of the Sample .................................................................................................... 12

II.4 Measuring the Falling Time.....................................................................................................................12

III. CALCULATIONS .................................................................................................14

III.1 Dynamic Viscosity ...................................................................................................................................... 14

III.2 Kinematic Viscosity .................................................................................................................................... 15

IV. DETERMINATION OF THE NON-NEWTONIAN BEHAVIOR ............................... 16

IV.1 ixotrophy/Rheopexy ................................................................................................................... 16

IV.2 Structural Viscosity (Pseudoplasticity and Dilatancy) ............................................................... 16

Appendix A - Maintenance ..................................................................................................17

Appendix B - Calibration of the Ball Constants ................................................................18

Appendix C - Online Help and Additional Resources ......................................................19

Appendix D - Warranty Repair and Service .......................................................................20

Page 4

Page 5

I. INTRODUCTION

Falling Ball Viscometer, Model KF40, complies with the German industry standard DIN 53015. The measuring principle, according to Höppler, is to determine the falling time of a ball in a

cylindrical glass tube lled with liquid. The working angle of the falling tube in the KF40 are variable at 80°, 70°, 60° and 50° relative to horizontal. The water jacket, surrounding the falling tube, when connected to a Brookeld circulating temperature bath provides for precise

temperature control of the sample.

The user calculates the dynamic viscosity of the sample by determining the falling time of the

ball between the upper and lower ring marks displayed on the falling tube. Using data on the ball constants, the density dierence between the liquid sample and the ball, and the working angle constant, a mathematical equation is used to convert the time measurement to a viscosity

value in centipoise.

Note: The ball constants (forwards and backwards) and ball densities are listed on the test

certicate accompanying the instrument. You must provide the density value for the liquid that you are testing.

The six (6) balls with dierent diameters and densities enable the KF40 to measure a wide

range of viscosities. The ability to adjust the angle of inclination extends the measuring range

for low viscosity liquids.

For non-Newtonian liquids, by subjecting the same sample to repetitive measurements with the KF40 at dierent angles, pseudoplastic or dilatant behavior may be determined as explained in Section IV. Time dependent behavior (thixotropy and rheopexy) may also be noted.

The ease of operation and precise temperature control, using a Brookeld circulating temperature

bath, allows for very reproducible measuring results.

I.1 Components

Component Part No. Quantity

KF40 Falling Ball Viscometer KF40 1

Set of (6) balls with gauge (FB68) in a carrying case (FB26) FB30C 1 Supplied w/certicate stating diameter and mass of each ball

-Ball 1 (glass) FB1 -

-Ball 2 (glass) FB2 -

-Ball 3 (nickel and iron) FB3 -

-Ball 4 (nickel and iron) FB4 -

-Ball 5 (steel) FB5 -

-Ball 6 (steel) FB6 -

Ball Tweezers FB51 1

Wire Cleaning Brush for Sample Tube FB53 1 Brush to clean loose debris from Falling Balls FB52 1

M19-354 Page 5

Page 6

Leather cloth for polishing Falling Balls FB70 1

Sealant ring (perbunane) A 16x20 FB31 4 Sealant ring (silicone) 10x14x2 FB32 1 Thermometer, 0°C to +100°C TM1 1

Operator Manual M11-353 1

Instrument Case FB200 1

Latex rubber tubing, 5/16 I.D. x 1/16 wall FB69 1

Certicate of Calibration ____ 1

I.2 Specifications

Viscosity Range: 0.5 - 7x104 mPa•s (cP)

Falling Time-Lower Limit: 60 s for Ball No.1

30 s for Ball Nos. 2,3,4,5 and 6

Falling Time-Upper limit: 300 s

Materials with viscosity >7x104 mPa•s require running times of over 300 s.

Measuring Distance: 100 mm (50 mm between adjacent ring marks) in both

directions

Fall Tube Inner Diameter: 15.94 mm +/- 0.01 mm

Set of Balls: 6 balls

Working Angle: KF40: 80°, 70°, 60°, 50°

Temperature Range: -5°C - +150°C

Sample Volume: 40 mL

Viscometer Accuracy: ±0.6% if the reading when used with balls 2 and 3.

Dimensions: 180 mm x 220 mm x 330 mm

Weight: 6.4 lbs, 2.9 kg (empty glass tube and empty waterbath jacket)

Page 6

M19-354

Page 7

I.3 Details on Viscosity Measurement Range and Accuracy

Per DIN 53015, the Falling Ball method is suitable for measuring dynamic viscosities ranging

from 0.6 mPa•s to 250,000 mPa•s at temperatures from -5ºC to 150ºC. Use is made of six balls having dierent diameters, each ball covering part of the range. All guideline values and

referenced parameters in the following table are per DIN 53015.

Viscosity Ball No.

1 0.5 to 10 Borosilicate glass 2.4 15.81 ± .01 ± 0.0005 0.007

2 9 to 140 Borosilicate glass 2.4 15.6 ± 0.05 ± 0.0005 0.09

3 40 to 700 Ni/iron 8.1 15.6 ± 0.05 ± 0.001 0.09

4 150 to 5,000 Ni/iron 8.1 15.2 ± 0.1 ± 0.001 0.7

5 1,500 to 50,000 Ni/iron 8.1 14.0 ± 0.5 ± 0.001 7

6 Above 7,500 Ni/iron 8.1 11.0 ± 1 ± 0.002 35

measurement

range (guideline

values) (mPa•s)

Material

Density (guideline value)

(g/cm

Ball diameter (mm)

Deviation from circularity (mm)

Calibration constant (guideline value) (mPa•s•cm3/g•s)

These are the accuracy values reported in the DIN53015 standard.

AMETEK Brookeld has determined the accuracy of the viscometer using balls 2 and 3 according to the method specied in the DIN53015 standard.

To determine the accuracy of the viscometer for balls 1, 4, 5 and 6, please refer to the method

specied in the DIN 53015 standard.

I.4 Description of the Equipment

Refer to Figures 1 and 2. Specic items identied on the Falling Ball Viscometer are identied by parentheses ( ) in the following steps:

1. The Falling Ball Viscometer must be level. The level is adjusted using the three Leveling

Feet (4) on the base. Adjust so that the bubble level on top of the Falling Ball Viscometer is centered within the circle. Check level periodically during use.

2. The working angles of the KF40 are 80°, 70°, 60° and 50° relative to horizontal. The DIN 53015 working position of 80° is the preferred position. The dierent working angles are secured by the adjustment screw (5). To select a working angle, the adjustment screw (5) should be loosened by turning it counter-clockwise approximately one rotation. After the working angle is selected, the adjustment screw should then be tightened again.

3. The two running directions of the balls can be chosen by swiveling the viscometer, which

is kept in place by the Stop to hold the viscometer in position (22).

4. The glass tube (6) is surrounded by a waterbath jacket (9) which is xed between the upper plate (7) and lower plate (8). The upper locking plug (16) with lid (20), the lower locking

M19-354 Page 7

Page 8

plug (17) and accompanying seals (19), and the caps (18) are designed to perform the

following functions within the sample tube:

a. keep the liquid sample tightly sealed.

b. eliminate the formation of air bubbles. c. avoid a build up of pressure

5. Mounted on the lower and upper plates are inlet/outlet ports (10a and 10b) for connection

to the water bath.

NOTE: Any alteration, modication or replacement of the sample tube, water jacket,

falling tube screw ttings, tension rods or balls renders the ball constants invalid and requires the re-calibration of the viscometer. See Appendix B.

6. The thermometer screw (11) and thermometer seal (13) with inserted thermometer is screwed into M10x1 Thermometer attachment thread (12) in the upper plate. The thermometer screw should be tightened securely to prevent uid leakage.

NOTE: Caution when handling the glass thermometer!

7. The primary function of the ball gauge is to distinguish the two glass balls (Ball No. 1 and

Ball No. 2) from each other. Ball No. 1 will not pass through the ball gauge, whereas Ball No. 2 will pass through. The ball gauge may also be used to help identify Ball No. 2 through

Page 8

Balls (set of 6) (p/n FB1-FB6)

Ball Gauge (p/n FB68)

Case (p/n FB26)

Foam Inserts (p/n FB27, FB28 & FB29)

Figure 1

NOTES:

Ball diameters, weights, densities and ball constants (forwards and backwards) are

listed in the test certicate accompanying the viscometer.

M19-354

Page 9

10b

10a

KF40

DIN

Figure 2: Falling Ball Viscometer KF40

1. Stand - KF40 (Part No. FB204) 13. Thermometer seal , 10mm x 14mm x 2mm

2. Viscometer (silicone) (Part No. FB32)

3. Bubble Level 14. Bearing for viscometer rotation

4. Leveling Feet (Part No. FB75) 15. Nuts

5. Adjustment screw for angle 16. Upper Locking Plug (Part No. FB64)

6. Glass Tube (15.94mm dia.) with s/n oriented 17. Lower Locking Plug (Part No. FB66)

towards the top of the instrument (Part No. FB76) 18. Cap (Part No. FB63)

7. Upper Plate 19. Viscometer seal A 16mm x 20mm (perbunane)

8. Lower Plate (Part No. FB31)

9. Waterbath Jacket (glass) (Part No. FB41) 20. Lid (for upper locking plug) (Part No. FB65)

10a. Inlet port for connection to water bath 21. Falling tube screw fitting (Part No. FB67)

10b. Outlet port for connection to water bath 22. Stop to hold viscometer in position

11. Thermometer screw (Part No. FB42) 23. Seal for falling tube (Part No. FB62)

12. M10x1 Thermometer Attachment Thread 24. Water Jacket Gasket (Part No. FB33)

M19-354 Page 9

Page 10

I.5 Safety Symbols and Precautions

Safety Symbols

The following explains safety symbols which may be found in this operating manual. Refer to the manual for specic warning or caution information to avoid personal injury

or damage to the instrument.

Precautions If this instrument is used in a manner not specied by the manufacturer, the protection

provided by the instrument may be impaired.

This instrument is not intended for use in a potentially hazardous environment.

The user should ensure that the substances placed under test do not release poisonous,

toxic or ammable gases at the temperatures to which they are subjected to during the

testing.

I.6 Cleaning

Great care should be given to cleaning of the sample tube, the locking plugs and the balls. These components (material: glass, Ni-iron, steel, perbunane, silicone, stainless steel surfaces) must not be damaged or subject to chemical action by the cleaning uid.

The cleaning procedure is to be carried out in the following sequence:

• The viscometer is pulled out of the bearing guide (14) in the stand by turning it 90° and

placed in a suitable collecting basin.

• Unscrew the caps and remove the locking plugs in such a way that the ball does not fall into the collecting basin (possibly damaging the ball). The ball collector (Part No. FB23) is an optional item that can be purchased on request.

• Clean the sample tube using a suitable cleaning agent for the material being measured with the cleaning brush (Part No. FB53).

• There must not be any residue remaining in the sample tube or on the balls after they have

been cleaned and are dry. Wipe with a cloth that will not leave bers, if necessary.

• When cleaning, be careful that the cleaning agent does not come into contact with the

equipment outside of the measuring tube.

Page 10

M19-354

Page 11

II. GETTING STARTED

II.1 Choice of Balls

The balls are chosen in such a way that the minimum falling time is not less than what is shown in the table and the maximum falling time is not greater than 300s. The DIN 53015 indicates that a falling time greater than 300s is allowed, but for practical reasons, a shorter test time

makes more sense.

Ball

No.

Diameter

[mm]

1 15.81 60 0.5 10

2 15.60 30 2.5 130

3 15.60 30 20 700

4 15.20 30 200 7800

5 14.00 30 1000 45000

6 11.00 30 5500 70000

The specications for the ball constant and the ball density are taken from the test certicate which came with the equipment.

The exchange of balls or equipment components between dierent viscometers is not permitted.

Otherwise, the ball constants lose their validity.

When the falling time for the ball is less than the minimum time, turbulence may occur.

II.2 Filling the Sample Tube

Minimum falling

time [s]

Lower measuring range limit

[mPa•s]

Upper

measuring range

limit [mPa•s]

To ll the sample tube:

• The sample tube is locked on the lower plate with the lower locking plug, seal, and cap.

• The liquid is lled up to approximately 25mm beneath the top of the sample tube without

air bubbles. Use a glass lter to remove any impurities when introducing a liquid into the

tube.

• The ball is polished with the leather cloth and bers are removed with the small cleaning

brush, before being inserted into the tube with the ball tweezers. The ball must not be touched after polishing. The ball will travel to the bottom of the tube. Possible air bubbles in the sample, or trapped below the ball, are removed with a suitable rod, by rotating the ball.

• Insert the upper locking plug with seal into the sample tube. In so doing, the sample must

enter the inside of the upper locking plug through the opening. The upper locking plug must

M19-354 Page 11

Page 12

not be lled more than half way with the sample in order to minimize pressure build-up due to the air bubbles. Due to the design of the upper locking plug, air bubbles cannot get into

the sample tube.

• The sample must be free of air bubbles between the two locking plugs. The lid of the upper locking plug is attached and the temperature control (desired test temperature) must be

achieved. After proper temperature control is achieved, the upper cap is screwed on.

Do not heat the sample with the upper lid attached as pressure may build in the tube.

NOTE: Gas bubbles can be removed by warming up the sample for a short time (approximately

20 degrees above the measuring temperature with the upper locking plug removed) or by lightly tapping on the lid of the upper locking plug.

II.3 Temperature Control of the Sample

The following are suggested working uids for the circulating temperature bath:

Temperature

Range

-5 to +20°C Water (distilled) - glycol-mixture; mixed in accordance with the manufacturer’s instructions for the temperature range

+1°C to +80°C Distilled water Latex tube

+80°C to +150°C Transparent thermostatic oil Insulated Fluran tube,

Bath Working Fluids Tubing

Insulated Latex tubing, secured with tube band clips

secured with tube band clips

The inlet and outlet ports should be oriented in the following manner. During initial ll of water jacket, the inlet will be at the bottom of the viscometer and the outlet will be at the top.

The tubing from the circulating bath should be pushed tightly onto the viscometer tubes. By

pulling gently, check whether the tubing is rmly attached. Tubing and circulating baths are available on request from AMETEK Brookeld or your local authorized dealer. If the water bath jacket has condensation on the glass, rub with alcohol.

The sample tube is sealed with the upper cap after temperature set point has been achieved.

Allow 30 minutes for thermal equilibrium.

Falling ball viscometers provide precise temperature control for the sample. By measuring your sample at multiple temperatures, you can determine the temperature viscosity curve.

Page 12

M19-354

Page 13

II.4 Measuring the Falling Time

Before beginning the measurement, the upper cap must be loosened (unscrewed) again to let o possible pressure.

The time which the balls take to run between the top and bottom ring marks in the sample tube is determined with a stop watch (resolution 0.01s).

It is recommended that you record the passage of the lower ball point using the ring marks as follows. Position your eyes at the same height as the ring marks so that these appear as a line. A dark paper, placed behind the viscometer with its edge at the same height as the ring mark,

shows the ball periphery more distinctly.

With dark liquids, you can better observe the ball in the sample tube by looking from behind

the instrument.

Possible variations in the measuring times may be due to impurities in the sample, air bubbles

or the fact that it has not been brought to the right temperature (insucient temperature control). Even 0.1°C change in temperature is clearly measurable. The rst forward and return passage of the ball can be used to achieve a thorough mixing (temperature equalization) of the sample

before running the viscosity test.

BALL BEGINS DESCENT

START STOPWATCH WHEN BOTTOM OF BALL CROSSES OVER THE RING MARK

BALL

BALL IN

TRANSIT

MIDPOINT

BALL FINISHES DESCENT

RING MARK

STOP STOPWATCH WHEN BOTTOM OF BALL CROSSES OVER RING MARK

M19-354 Page 13

Page 14

III. CALCULATIONS

III.1 Dynamic Viscosity

With Newtonian liquids absolute values of the dynamic viscosity are calculated, where as, for non-Newtonian liquids, relative values of the dynamic viscosity (apparent viscosity) are

calculated.

The dynamic viscosity is calculated according to the following equation:

Equation 1: η = t(ρ

where: η dynamic viscosity [mPa•s] t traveling time of the ball [s] ρ1 density of the ball according to the test certicate [g/cm3] ρ2 density of the sample [g/cm3]

K ball constant according to test certicate [mPa·cm3/g] F working angle constant

- ρ

)K•F

Angle of inclination a

(applied to the level)

80° (DIN) 1.0

70° 0.952

60° 0.879

50° 0.778

Working angle constant F

The density and ball constant are each stated in the test certicate.

Consideration for buoyancy of the ball in the sample is accounted for by means of (ρ1-ρ2) in equation (1).

The density of the sample can be determined by:

• referring to the material specications from the manufacturer of the uid

• measuring with a densitometer

Note: Be sure to measure the sample density at the same temperature at which the viscosity will be measured.

As ρ

sity of the sample to be determined to 0.001g/cm3 (3rd decimal position) for the glass balls and

- ρ

becomes small, a higher resolution on density measurement is required. The den-

0.01g/cm3 (2nd decimal position) for the metal balls.

Page 14

M19-354

Page 15

III.2 Kinematic Viscosity

The conversion of the dynamic viscosity into the kinematic viscosity is accomplished using the following equation:

Equation 2:

ν =

ν Kinematic viscosity [mm2/s] η Dynamic viscosity [mPa•s] ρ2 Density of the sample [g/cm3]

M19-354 Page 15

Page 16

IV. DETERMINATION OF THE NON-NEWTONIAN BEHAVIOR

Non-Newtonian behavior can be determined when dierent measurement times are recorded

with repeated tests.

IV.1 Thixotrophy/Rheopexy

Thixotropy (rheopexy) is indicated if the traveling times for a ball decreases (increases) when

repeated measurements are made on the same volume of sample.

NOTE: If temperature control is not done correctly, thixotropy or rheopexy can be

inferred by mistake.

Rotational or Capillary Viscometers should be used for better determination of ow behavior.

IV.2 Structural Viscosity (Pseudoplasticity and Dilatancy)

Using the KF40 Falling Ball Viscometer at dierent angles may serve to determine pseudoplastic or dilatant behavior for non-Newtonian liquids. If the sample is non-Newtonian, the travel time of the ball multiplied by the sine of the working angle for the KF40 will not remain constant. This infers non-Newtonian ow behavior. For pseudoplasticity, the calculated value decreases;

for dilatancy, it increases.

NOTE: If temperature control is not done correctly, pseudoplasticity or dilatancy can be

inferred by mistake.

Details about the relative values for pseudoplasticity and dilatancy are related to the diameter

of the ball and the working angle.

More sophisticated equipment, like rotational viscometers/rheometers, should be used for

detailed examination of non-Newtonian materials.

Page 16

M19-354

Page 17

Appendix A - Maintenance

A.1 Exchanging the Sample Tube

1. Loosen the two set screws of the sample tube screw ttings (above and below).

a. Empty the water jacket and sample tube. Make sure the water jacket is clean on the

2. Unscrew both of the sample tube screw ttings using a ring nut key.

3. Pull o the rubber seal (washer) on one end of the sample tube.

4. Pull the sample tube out at the other end.

5. Insert the new sample tube and also wet the sample tube gaskets and washers.

6. Assemble the sample tube in the reverse order. Observe that the ends of the sample tube

7. Re-calibrate all the ball constants according to Appendix B.

Caution Glass Components. Excessive force may result in broken glass.

inside surface before reassembling.

project evenly from the upper and lower plates.

A.2 Exchanging the Water Bath Jacket

1. Remove the sample tube.

2. Unscrew the upper and lower plates on the connecting bar.

3. Unscrew the three lower nuts on the viscometer.

4. Replace rubber washers and insert the new water bath jacket.

5. Put on the upper plate and screw down the nuts evenly.

6. Fix the lower plate an the lower connecting bar.

7. Assemble the sample tube.

8. Calibrate all the ball constants according to Appendix B.

Caution Glass Components. Excessive force may result in broken glass.

a. Empty the water jacket and sample tube. Make sure the water jacket is clean on the

inside surface before reassembling.

A.3 Exchanging the Ball or the Viscometer

1. Exchange the balls or viscometer.

2. Re-calibrate the ball constants according to Appendix B.

M19-354 Page 17

Page 18

Appendix B - Calibration of the Ball Constants

Brookeld’s certication of the instrument is performed with Ball #2 and Ball #3 as well as using the Cannon N44 viscosity standard with a nominal value of 92 mPa•s at 20°C.

Re-calibration of the ball constants is required by the operator if:

1. changes in the sample tube or water jacket were made

2. one or more balls were replaced

The calibration requires the use of a Newtonian mineral oil viscosity standard. Choice of the viscosity standard is according to the ball. Use the appropriate Cannon or Brookeld viscosity

standard that falls within the viscosity measurement range.

BALL NO. 1 2 3 4 5 6

Recommended Viscosity

Standards

(cP, mPa•s)

The calibration is made according to the method in DIN 53015 at 20°C ± .05°C. A suitably calibrated thermometer can be obtained from your local authorized dealer, on request.

Cannon Cannon Cannon Cannon Cannon N/A

S3 N10 N100 N350 N1000 N/A

3.9 cP @

20°C

21 cP @

20°C

283 cP @

20°C

830 cP @

20°C

2900 cP @

20°C

N/A

Ball #6 is not recommended for use in performing a calibration check.

The ball constants are determined from (5) running times, in both forward and reverse direction.

The ball constant is calculated according to the following equation:

Equation 3:

K =

(ρ1-ρ2)

• t

t Mean value from 5 running times [s]

η Dynamic viscosity of the calibrating uid [mPa•s] at 20°C ± .05 C ρ1 Density of ball [g/cm3] ρ2 Density of calibrating uid [g/cm3]

Note: Be sure to measure the sample density at the same temperature at which the viscosity will be measured.

The expected value of the constant should be similar to the constant stated in the test certicate.

For Ball No. 6, the ball constant changes insignicantly as a function of the falling tube diameter and diameter of the ball, so that the ball constant is calculated according to the following equation:

Equation 4:

K6 = 1.4057(D-d6)

(0.75042+1.82637 )

d D

D Falling tube diameter (15.94 mm)

d6 Diameter of Ball No. 6 (see calibration certicate) K6 Ball constant of Ball No. 6

Page 18

M19-354

Page 19

Appendix C - Online Help and Additional Resources

www.brookeldengineering.com

The Brookeld website is a good resource for additional and self-help whenever you need it. Our website oers a selection of “how-to” videos, application notes, conversion tables, instructional manuals,

material safety data sheets, calibration templates and other technical resources.

www.youtube.com/user/BrookeldEng

Brookeld has its own YouTube channel. Product and Application Videos can be found here.

Article Reprints

Available in Print Only

- Brookeld has an extensive library of published articles relating to viscosity, texture and

powder testing. Due to copyright restrictions, these articles cannot be emailed. Please

request your hard copy of articles by calling our customer service department directly or

by emailing: MA-MID.sales@ametek.com.

Available Online

- Brookeld has a growing number of published articles that can be downloaded directly

from the Brookeld website. These articles can be found on our main site by following this path: www.brookeldengineering.com/learning-center/articles-and-technical-papers