Transcript
SPECIFIC GRAVITY MEASURING KIT
for ASB series for BPS series for ABX series
MRCLTD HAGAVISH 3 HOLON ISRAEL TEL. 972-3-5595252 FAX. 972-3-5594529 E-Mail:
[email protected]
Contents 1. INTRODUCTION .............................................................................................. 3 2. PRINCIPLE OF DENSITY MEASUREMENT ................................................... 4 2.1. DEFINITIONS ........................................................................................... 4 2.2. ERROR FACTORS ................................................................................... 5 3. MEASURING KIT – COMPONENTS ............................................................... 7 3.1. Measuring kit for precision balances .................................... .................... 7 3.2. Measuring kit for analytical balances ........................................................ 8 4. INSTALLATION OF THE COMPONENTS FOR ANALYTICAL BALANCES ......................................................................................................... 9 4.1 INSTALLATION FOR THE COMPONENTS FOR PRECISION BALANCES ................................................................................................... 10 4.2 INSTALLATION FOR THE COMPONENTS FOR ANALYTICAL BALANCES AS SERIES ................................................................................ 11 5. MEASURING THE DENSITY FOR BALANCES............................................ 12 5.1. DENSITY FUNCTION IN THE BALANCE MENU ................................... 12 5.2. FUNCTION ACTIVATION ....................................................................... 13 5.3. SOLID DENSITY – VIEW MENU ............................................................ 13 5.4. LIQUID DENSITY – VIEW MENU ........................................................... 14 5.5. MEASURING THE DENSITY OF A SOLID ............................................ 15 5.6. MEASURING THE DENSITY OF A LIQUID ........................................... 18 6. MEASURING THE DENSITY OF SOLIDS FOR BALANCES PS SERIES.... 21 6.1. MEASURING THE DENSITY OF SOLIDS ............................................. 21 6.2. MEASURING THE DENSITY OF A LIQUID ........................................... 27 7. MEASURING THE DENSITY BALANCES .................................................... 31 7.1. DENSITY FUNCTION IN THE BALANCE MENU ................................... 31 7.2. MEASURING THE DENSITY OF A SOLIDS .......................................... 32 7.3. MEASURING THE DENSITY OF A LIQUID ........................................... 36 8. MANUFACTURER’S RECOMMENDATIONS ............................................... 41
Table 1. Dependences of density of distilled water on the temperature....... 42 Table 2. Dependences of density of water on the temperature (Official Journal of Measures No 7/94) ...................................................................... 43 Table 3. Density of some substances (Engineer Mechanic Guide Volume 1)...................................................................................................... 44 Table 4. Density if some liquids at 20 °C (Engineer Mechanic Guide Volume 1)...................................................................................................... 44
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1. INTRODUCTION Density of solids and liquids is measured in most of the laboratories. 0R& company prepared software which improves process of measuring density. In traditional method operator has to perform many laborious measurement and toilsome measurements. In effect the result of density measurement can be faulty. User needs a lot of time to determine density of liquid or solid. If balances with function for measure density of solids or liquids is used this procedure can be simplified and quickened. Time which user needs to receive final result is short because all countings are performed by balance software. User operates the balance keyboard, puts samples on the pans and hooks the float only. The density of solids and liquids can be determined by the measuring kit. It is part of the additional equipment of laboratory balance. The software has following advantages: • Simplicity of operation (all activities are presented on the display to user), • reliability (all counting are done automatically), • fast processing of the data (user receives the result after determination sample mass in water or float in the liquid), • reliable processing of the data (before every measurement the indication is set to zero. The results are reliable), • printing results on any printer or sending them to computer to transform them.
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2. PRINCIPLE OF DENSITY MEASUREMENT 2.1. DEFINITIONS • Density Density refers to the total amount of mass of sample per unit volume.
/ ρ M V
- density - mass - volume
• Specific gravity Specific gravity refers to the ratio of the density of a sample to the density of pure water (with the same volume as that of the sample) at 4oC, at pressure 1013,25 hPa.
S M V ρn
- specific gravity - mass - volume - density of water at 4oC, at pressure 1013,25 hPa
• Archimedes’ Principle A body immersed in a fluid undergoes an apparent loss in weight equal to the weight of the fluid it displaces. • Density of solid The density of solid can be obtained according to the weight of the sample of the specimen in air and the density of the liquid.
ρ A B ρo
- density of specimen - weight in air - weight in liquid - density of liquid -4-
• Density of liquid The density of a liquid is obtained in accordance with following formula:
ρ A B V d
- density of liquid - weight of float in air - weight of float in liquid - volume of float - density of air ( max 0,001 g/cm3 )
2.2. ERROR FACTORS The software counts and shows density results on the digital display with capacity 0,001 g/cm3. The result may have some errors. • Error of mass measurement Sample mass (in the air and in the water) is obtained by balance with accuracy 0,001g. • Buoyancy of Air The buoyancy of air is obtained by:
1 t p
0,0012932 0,0036728
1013,25
- air temperature [oC] - air pressure
• Temperature of liquid When the density of solid is measured the density of liquid changes with the temperature. Density of liquid (H2O and C2H5OH) is collected from tabels in the balance processor by the balance software depending on temperature of liquid before the measurement. Density of other liquid is noted in the balance memory by user before density measurement. Corrections of density of distilled water and alcohol are noted by the balance software automatically. -5-
• Volume of Float The tolerance of measured value of the volume of float is ± 0,005 cm3. • Surface tension When the density of a solid is measured a force (surface tension) is applied to the pan between the wire (0,2 mm in dia) of the pan and the surface of the liquid. This force has no influence on result of measurement. • Bubbles The buoyancy of a bubble of 1 mm in diameter is about 0,5 mg. Stickiness of bubbles depends on the shape and material of a specimen. Make measurements considering these characteristic of bubbles. Air bubbles stick to greasy surfaces easily.
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3. MEASURING KIT – COMPONENTS 3.1. Measuring kit for precision balances
Draw 1. Components of the KIT for precision balances
Components of the kit: 1 2 3 4 5 6
Pan stand Bottom pan Wire Top pan for density of solids measurement Beaker Float hook
7 8 9
Thermometer Thermometer clamp Float
10
Beaker stand
11
Additional pan stand
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3.2. Measuring kit for analytical balances
Draw 2. Components of the KIT for analytical balances
Components of the kit: 1 2 3 4 5 6
Beaker stand Pan stand Float Beaker Thermometer clamp Thermometer
7 8 9 10 11 12
Wire Float hook Top pan Wire Bottom pan Additional weights
Attention: − Store the components in the kit box. − Do not put pans set and float on the table because these elements can be damaged. − If pans set or float are not used they should be stored on additional stand.
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4. INSTALLATION OF THE COMPONENTS FOR ANALYTICAL BALANCES XA SERIES Take the pan off. Install gravity measuring kit as it is presented on the drawing below.
Draw 3. installation of the components
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4.1 INSTALLATION FOR THE COMPONENTS FOR PRECISION BALANCES
Draw 3.1. installation of the components
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5. MEASURING THE DENSITY BALANCES 5.1. DENSITY FUNCTION IN THE BALANCE MENU
Draw 4. The balance menu – density function
The density value should be set as 1 (enabled). It is possible to get directly to this function through MODE button.
Draw 5. Buttons on the balance keyboard
If specific gravity measuring kit is installed on the balance it is not possible to calibrate the balance correctly. To perform calibration process put the pan instead of gravity measuring kit. - 12 -
1. INTRODUCTION Density of solids and liquids is measured in most of the laboratories. R& company prepared software which improves process of measuring density. In traditional method operator has to perform many laborious measurement and toilsome measurements. In effect the result of density measurement can be faulty. User needs a lot of time to determine density of liquid or solid. If balances with function for measure density of solids or liquids is used this procedure can be simplified and quickened. Time which user needs to receive final result is short because all countings are performed by balance software. User operates the balance keyboard, puts samples on the pans and hooks the float only. The density of solids and liquids can be determined by the measuring kit. It is part of the additional equipment of laboratory balance. The software has following advantages: • Simplicity of operation (all activities are presented on the display to user), • reliability (all counting are done automatically), • fast processing of the data (user receives the result after determination sample mass in water or float in the liquid), • reliable processing of the data (before every measurement the indication is set to zero. The results are reliable), • printing results on any printer or sending them to computer to transform them.
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Temperature Temperature which is presented on the display and should be written during the procedure. For OTHER read out the density in the table. The tables show dependences on the temperature. Density Density of liquid which depends on the temperature. For WATER and ALCOHOL this value is counted automatically. For OTHER write the density of liquid. Statistics Statistics counting for following density measurements. Run Start the procedure. 5.4. LIQUID DENSITY – VIEW MENU
Draw 8. Liquid density – view menu
Procedure Select the procedure of density of solids and liquids measuring. Sinker volume Capacity of the float is presented on the float hook. Record this value in the balance memory. Statistics Statistics counting for following density measurements. Run Start the procedure. - 14 -
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Press the ENTER button when the result is stable.
End of procedure.
Draw 25. End of procedure – final result
Function keys:
Draw 26. Function keys
6. MEASURING THE DENSITY OF SOLIDS
6.1. MEASURING THE DENSITY OF SOLIDS Take the pan off and install measuring kit following point. 7. Set the beaker on the stand so that it does not touch the pan. Attach the thermometer clamp to the beaker and insert the thermometer in the thermometer clamp holes. Pour a liquid into the beaker (distilling water, alcohol or any other with known density)to about ¾ of the capacity. Place the pan on the pan stand centrally. Put the pan stand in the central position of beaker, then check the temperature in the beaker. Remember to keep the temperature inside beaker stable during measurements (the density of liquids depends on the temperature - can change results of measurement). The kit is prepared to measurements now.
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Procedure: • • •
Press key Mode, pressing UNITS key choose submenu F6 d_Co, Select one of the 3 liquids H20 (disilled water), C2H5OH (spirit 100% ± 0.1% in temp. 200C) or Another (any other liquid with known density), for H20 and C2H5OH, give the temperature of the liquid and follow below instructions,
Draw. 27. Procedure of density solids determination (selected liquid is H20).
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•
For selected liquid Another, give the liquid density and follow the procedure on the picture below
Draw. 28. Procedure of solids density determination (selected liquid: Another).
• •
After selecting type of the liquid the balance shows Load A then zero (if the balance does not show zero press ESC/ZEROTARA), Then put the sample on the upper pan and weight it in the air.
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•
Balance shows density in [g/cm3].
During measurements check if there is any air bubbles on the surface of the sample. They can cause errors in measurements. .
To select other liquid press F:
Draw. 32. Method of reselecting liquid
To return to weighing press Mode and then press Zero/Tara:
Draw. 33. Return to weighing
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To weight the sample again press the key Units:
Draw. 34. Procedure of return to weighing.
6.2. MEASURING THE DENSITY OF A LIQUID Take the pan off ,install the measuring kit following the point 7. If „null” is on the display, use additional load on the kit. Then press Zero/Tara, if there is different value to zero on the display. Then pour the liquid into the beaker – the plunger should be immersed in the liquid completly. Procedure • •
Press key Mode, then select submenu F7 d_Li, Then enter capacity of the plunger, accuracy of the capacity depends on the value given
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Draw. 35. Measuring the density of liquids.
•
After capacity of the plunger is entered into balance memory (key Print/Enter) balance shows command Load A and zero (if the balance does not show zero press ESC/ZEROTARA), - 28 -
To enter density of the pluger again, press F:
Draw. 37. Entering density of plunger
To return to weighing press Units, and then key Zero/Tara:
Draw. 38. Return to weighing.
To restart weighing plunger in the air press Units:
Draw. 39. Procedure of beginning following weighing.
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7. MEASURING THE DENSITY BALANCES 7.1. DENSITY FUNCTION IN THE BALANCE MENU
Draw 40. Balances menu – LCD series
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7.2. MEASURING THE DENSITY OF A SOLIDS Procedure: −
− −
Press key MODE. Pressing UNITS key, choose F6 d_Co. Press PRINT to start density function. Press UNITS key and select liquid in with density will be determined.
Draw 41. Solids density – select liquid
Thickness of solids can be tested in one of 3 liquids: • H2O (distilled water), • C2H5OH (spirit 100% +/- 0.1% in temp. 20°C), • AnotHEr (another liquid with known thickness). − After selecting liquid confirm by PRINT.
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−
If H2O or C2H5OH are selected the program moves to following step, introducing actual liquid temperature. The information on the display enables to introduce liquid temperature from the thermometer. Enter the temperature using UNITS or MODE key.
Draw 42. Solids density – set temperature
−
After adjusting the temperature, press PRINT key to confirm it.
If AnotHEr liquid was selected after pressing ENTER key the program moves to following step when the density of the liquid should be noted. Introduce the density value of this liquid by function key of the balance.
− − −
Press the UNITS or MODE key to change the digit value. Press the F key to select the digit. After adjusting the temperature press PRINT key to confirm it.
After writing information about the liquid parameters the balance software moves to following process steps automatically. Commands which inform user that the software is ready to receipt following data (mass of the sample in air and in liquid) necessary to correct counting density of examined sample.
Draw 43. Solids density – measure in air
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Key function after procedure
The result is presented on the display in [g/cm3]. It does not change even when the sample is taken off. Press F key to do back to menu. 7.3. MEASURING THE DENSITY OF A LIQUID Basic element for measuring thickness of liquid is glass plunger. It has precise capacity shown on hook. INSTALLATION 1. Disassemble the pan. 2. Set the pan stand on the bumpers. 3. Set the beaker stand so that it does not touch the pan stand (as it is presented on below drawing). 4. Attach the thermometer clamp to the beaker and insert the thermometer in the thermometer clamp holes. 5. Pour liquid (about ¾ of the capacity) – which specific gravity is known – into the beaker and place the beaker on the beaker stand. 6. Hook the float on the float hook. 7. Wait until the temperature stabilizes, the result on the thermometer do not change. 8. Preparations for measurement are now completed.
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− − −
Press PRINT to start density function. Order to write float capacity vol appears on the display. The volume of float can be noted with the same accuracy as the balance shows. If actual scale interval is 0.001 g in the balance the volume stamped on the float hook should be noted with accuracy to 3rd place after the decimal point.
Write the volume of float using the keys: − − −
Press the MODE or UNITS key to change the digit value. Press the F key to select the digit. Press PRINT key to confirm value.
If the density of liquid is performed last float capacity appears on the display. Check if it is the same as the volume of the float stamped on the hook.
Draw 49. Liquids density – set volume of float
The volume of the float is noted into the balance memory. LoAd A and 0.000 appears on the display.
Draw 50. Liquids density – step 1
Weight the float in air, hook it on the pan stand without beaker.
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The result is presented on the display in [g/cm3]. It does not change even when the sample is taken off. 8. MANUFACTURER’S RECOMMENDATIONS 1. Density of solids should be determined after more than one measurement. 2. Examined sample should be degreased. 3. If the sample is oval it is difficult to catch it by the tweezers. It is necessary to cut notch which simplifies catching the sample. 4. The surface of the sample cannot be rough. Air bubbles fasten to rough surfaces easily. 5. Before every measurement dry the sample. If the sample is not dried the sample mass in air is different during following measurement and density counted by the balance software is faulty. 6. Set samples on the pans gently to avoid impacts. 7. Adjust the amount of the liquid so that the bottom pan arm is all immersed. 8. Select the sample mass to size of the pans. 9. The sample mass should be bigger than 5g. 10. Element which can cause errors is water on the tweezers. The tweezers should be also dried. 11. Density of liquids should be determined after few measurements. 12. Temperature of examined temperature should be stable. 13. The beaker should be degreased. If the surface is greasy air bubbles fasten easily to the sample and causes errors. 14. Wash the beaker before the measurement. 15. Adjust the amount of the liquid so that the specimen is 10 - 15 mm below the surface of the liquid. 16. Hook the float gently to avoid impacts. 17. Element which can cause errors is examined liquid. It fastens to the float. The mass of the liquid can be different in following measurements. The float should be dried after every weighing in liquid.
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CAUTION − Do not use plastic cloth to dry the float because it causes electric charge. It is recommended to wet the cloth in antistatic agent. − If the float is damaged during exploitation (breaks) it is not repared under the conditions of guarantee. Table 1. Dependences of density of distilled water on the temperature TEMP
0
1
2
3
4
0
0,99984
0,99990
0,99994
0,99996
0,99997
10
0,99970
0,99961
0,99949
0,99938
0,99924
20
0,99820
0,99799
0,99777
0,99754
0,99730
30
0,99565
0,99934
0,99503
0,99470
0,99437
TEMP
5
6
7
8
9
0
0,99996
0,99994
0,99990
0,99985
0,99978
10
0,99910
0,99894
0,99877
0,99860
0,99841
20
0,99704
0,99678
0,99651
0,99623
0,99594
30
0,99403
0,99368
0,99333
0,99297
0,99259
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Table 2. Dependences of density of water on the temperature (Official Journal of Measures No 7/94) [°C]
Density of water [g/cm3]
17,0
0,9988
17,5
0,9987
18,0
0,9986
18,5
0,9985
19,0
0,9984
19,5
0.9983
20,0
0,9982
20,5
0,9981
21,0
0,9980
21,5
0.9979
22,0
0,9978
22,5
0,9977
23,0
0,9975
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Table 3. Density of some substances (Engineer Mechanic Guide Volume 1) Name Bakelite Cotton Trick Sugar Wood oak Felt Gum Linoleum Building paper Paper Leather Polished plate glass Peat Calcareous plaster Glass wool Wax
Density [kg/m3] 1270 1300 1400 1600 900 300 1200 1200 1100 900 1000
Copper Aluminium Iron Platinum Gold Silver Molibden Tin Lead Cadmium Mercury
Density [g/cm3] 8,9 2,7 7,8 21,4 19,3 10,5 10,2 7,3 11,4 8,65 13,6
2550
Ind
7,3
130
Bismuth
9,9
1700
Tantal
16,6
200 950 – 980
Nickel Brass
8,9 8,4 - 8,7
Name
Table 4. Density if some liquids at 20 °C (Engineer Mechanic Guide Volume 1) Name Ammonia Petrol Glycerine Nitric acid 20%
density [kg/m3] 610 680 – 740 1260 1120
Name Spindle oil Kerosene Ice 0o C Acetic acid
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Density [kg/m3] 871 800 - 850 917,6 1050
