Density of Oil

Density of Oil
Tribology Wikipedia > Density of Oil

What is oil density?

Oil density is a crucial property not only in lubricants but in all fluids. For instance, as the density of a lubricant increases, the fluid becomes thicker. This leads to an increase in the amount of time it takes for particles to settle out of suspension. But before going forward we need to understand what density is?

The density is also known as the specific mass, is its mass per unit volume. Mathematically, density is defined as mass divided by volume.

The formula for density is d = M/V, where d is density, M is mass, and V is volume.

Density offers a convenient means of obtaining the mass of a body from its volume or vice versa; the mass is equal to the volume multiplied by the density (M = Vd), while the volume is equal to the mass divided by the density (V = M/d). The weight of a body, which is usually of more practical interest than its mass, can be obtained by multiplying the mass by the acceleration of gravity.

Measuring Density of Lubricants:

Density plays a critical role in how lubricant functions and how machines perform. Most systems are designed to pump a fluid of a specific density, so as the density begins to change, the pump’s efficiency begins to change as well.

The density of most oils will range between 700 and 950 kilograms per cubic meter (kg/m3). In oils, it is usually indicated in the temperature of +15°C or +20°C, in units kg/m3. Water has a density of 1,000 kg/m3. This means that most oils will float on water as they are lighter by volume. If the density of an object is less than that of water, then that object will float. This is why if you have a moisture problem in your lube system that the water settles to the bottom of the sump and is drained out first whenever the plug is pulled, or the valve is opened. This is not always the case, as some Group IV base oils can have a higher density than water, effectively causing the oil to sink in the water.

Density Unit Conversion

Here is a simple density (and viscosity) units conversion tool:

Density Temperature Relation

Density depends on temperature, even though the dependency is relatively small compared to lubricant viscosity. Here is an empirical formula that can be used to calculate the change of density with temperature (Grease Lubrication in Rolling Bearings):

(1)    \begin{eqnarray*} \rho = \rho_{T_1} + \alpha_p (T_1 - T) \\ \end{eqnarray*}

where  \alpha_p=0.65 for  831kg/m^3 <\rho<950 kg/m^3 and  \alpha_p=0.6 for  950 kg/m^3 <=\rho<1000 kg/m^3 . As it can be seen, this empirical relation applies only for the oils having the densities in a specified range, however, this range covers most commonly used lubricating oils (860-980  kg/m^3 kg/m^3 )

Here is a simple calculator that uses this equation to calculation density at the given temperature:

Density Pressure Relation

When the lubricating oil is compressed, density of the oil increases. This increase starts to be noticeable at relatively high pressures (>0.1GPa), which is however quite common for Elastohydrodynamic conditions (EHL). In EHL, the most widely used formulat to describe the change of oil density with pressure is known as Dowson an Higginson density equation:

(2)    \begin{eqnarray*} \rho = \rho_{0} \frac{0.59 \times 10^9 + 1.34p}{0.59 \times 10^9 + p} \\ \end{eqnarray*}

Here is a simple density calculator based on pressure:

Density Test Standard

ASTM D5002-19: Standard Test Method for Density, Relative Density, and API Gravity Of Crude Oils By Digital Density Analyser. This test method covers the determination of the density, relative density, and API gravity of crude oils that may be handled generally as liquids at test temperatures between 15 °C and 35 °C utilizing either manual or automated sample injection equipment. This test method applies to crude oils with high vapour pressures, provided appropriate precautions are taken to prevent vapour loss during the transfer of the sample to the density analyser.

This test method was evaluated in interlaboratory study testing using crude oils in the range of 0.75 g/mL to 0.95 g/mL. Lighter crude oil may require special handling to prevent vapour losses.

ASTM D1298-12: Standard Test Method for Density, Relative Density (Specific Gravity), or API Gravity of Crude Petroleum and Liquid Petroleum Products by Hydrometer Method. This test method covers the laboratory determination using a glass hydrometer in conjunction with a series of calculations of the density, relative density, or API gravity of crude petroleum, petroleum products, or mixtures of oil and nonpetroleum products generally handled as liquids, and having a Reid vapour pressure of 101.325 kPa (14.696 psi) or less. Values are determined at existing temperatures and corrected to 15°C or 60°F by means of a series of calculations and international standard tables.

Density of Oil Calculator:

The recalculation of the density of oil for different temperature and pressure values. Formulas are taken from Russia’s GOST R 8.610-2004. “State system for ensuring the uniformity of measurements for the density of oil. The tables for recalculation” standard. Used formulas are listed below the calculator.

Note: https://planetcalc.com/2834/ Link of oil density calculator. There is an option of embedding the calculator. You can use that calculator.

Densities of some common liquids

Liquid Temperature (t) – (Degree C) Density (ρ) – (kg/m3)
Acetaldehyde 18 783
Acetic Acid 25 1049
Acetone 25 784.6
Acetonitrile 20 783
Acrolein 20 840
Acrolonitrile 25 801
Alcohol, ethyl (ethanol) 25 785.1
Alcohol, methyl (methanol) 25 786.5
Alcohol, propyl 25 800
Almond kernel oil 25 910
Alyllamine 20 758
Ammonia (aqua) 25 823.5
Aniline 25 1019
Anisole 20 994
Apricot kernel oil 25 910
Argan seed oil 20 912
Automobile oils 15 880 – 940
Avacado pulp oil 25 912
Babassu palm oil 25 914
Beef tallow (land animals) 25 902
Beer (varies) 10 1010
Benzaldehyde 25 1040
Benzene 25 873.8
Benzil 15 1230
Blackcurrant oil 20 923
Borneo tallow 100 855
Brine 15 1230
Bromine 25 3120
Butanal 20 802
Butterfat (land animals) 15 934
Butyric Acid 20 959
Butane 25 599
2,3-Butandione 18 981
2-Butanone 25 800
n-Butyl Acetate 20 880
n-Butyl Alcohol (Butanol) 20 810
n-Butylhloride 20 886
Cameline oil 15 924
Canola rapeseed oil 20 915
Caproic acid 25 921
Carbolic acid (phenol) 15 956
Carbon disulfide 25 1261
Carbon tetrachloride 25 1584
Carene 25 857
Cashew nut oil 15 914
Castor oil 25 952
Cherry kernel oil 25 918
Chicken fat 15 918
Chinese vegable tallow 25 887
Chloride 25 1560
Chlorobenzene 20 1106
Chloroform 20 1489
Chloroform 25 1465
Citric acid, 50% aqueous solution 15 1220
Cocoa butter 25 974
Coconut oil 40 930
Cod liver oil 15 924
Cohune nut oil 25 914
Corn oil 20 919
Corriander seed oil 25 908
Cotton seed oil 20 920
Crambe oil 25 906
Cresol 25 1024
Creosote 15 1067
Crude oil, 48o API 60oF (15.6oC) 790
Crude oil, 40o API 60oF (15.6oC) 825
Crude oil, 35.6o API 60oF (15.6oC) 847
Crude oil, 32.6o API 60oF (15.6oC) 862
Crude oil, California 60oF (15.6oC) 915
Crude oil, Mexican 60oF (15.6oC) 973
Crude oil, Texas 60oF (15.6oC) 873
Cumene 25 860
Cyclohexane 20 779
Cyclopentane 20 745
Decane 25 726.3
Diesel fuel oil 20 to 60 15 820 – 950
Diethanolamine 20 1097
Diethyl ether 20 714
o-Dichlorobenzene 20 1306
Dichloromethane 20 1326
Diethyl ether 20 714
Diethylene glycol 15 1120
Diethylene glycol diethyl ether 20 906
Dichloromethane 20 1326
Diisopropyl ether 25 719
Dimethyl acetamide 20 942
N,N-Dimethylformamide 20 949
Dimethyl sulfate 20 1332
Dimethyl sulfide 20 848
Dimethyl sulfoxide 20 1100
Dodecane 25 754.6
Ethane -89 570
Ether 25 713.5
Ethylamine 16 681
Ethyl Acetate 20 901
Ethyl Alcohol (Ethanol, pure alcohol, grain alcohol or drinking alcohol) 20 789
Ethyl Ether 20 713
Ethylene Dichloride 20 1253
Ethylene glycol 25 1097
Euphorbia lagascae seed oil 25 952
Trichlorofluoromethane refrigerant R-11 25 1476
Dichlorodifluoromethane refrigerant R-12 25 1311
Chlorodifluoromethane refrigerant R-22 25 1194
Formaldehyde 45 812
Formic acid 10% concentration 20 1025
Formic acid 80% concentration 20 1221
Fuel oil 60oF (15.6oC) 890
Furan 25 1416
Furforal 25 1155
Gasoline, natural 60oF (15.6oC) 711
Gasoline, Vehicle 60oF (15.6oC) 737
Gas oils 60oF (15.6oC) 890
Glucose 60oF (15.6oC) 1350 – 1440
Glycerine 25 1259
Glycerol 25 1126
Grape seed oil 20 923
Hazelnut oil 25 909
Heating oil 20 920
Hempseed oil 25 921
Heptane 25 679.5
Herring oil 20 914
Hexane 25 654.8
Hexanol 25 811
Hexene 25 671
Hexylamine 20 766
Hydrazine 25 795
Illipe mowrah butter 100 862
Ionene 25 932
Isobutyl Alcohol 20 802
Iso-Octane 20 692
Isopropyl Alcohol 20 785
Isopropylbenzene hydroperoxide 20 1030
Isopropyl Myristate 20 853
Kapok seed oil 15 926
Kerosene 60oF (15.6oC) 820.1
Linolenic Acid 25 897
Linseed oil 25 924
Machine oil 20 910
Mango seed oil 15 912
Menhaden oil 15 920
Mercury 13590
Methane -164 465
Methanol 20 791
Methylamine 25 656
Methyl Isoamyl Ketone 20 888
Methyl Isobutyl Ketone 20 801
Methyl n-Propyl Ketone 20 808
Methyl t-Butyl Ether 20 741
N-Methylpyrrolidone 20 1030
Methyl Ethyl Ketone 20 805
Milk 15 1020 – 1050
Moringa peregrina seed oil 24 903
Mustard seed oil 20 913
Mutton tallow 15 946
Naphtha 15 665
Naphtha, wood 25 960
Napthalene 25 820
Neem oil 30 912
Niger seed oil 15 924
Nitric acid 0 1560
Oat been oil 25 904
Oat oil 25 917
Ocimene 25 798
Octane 15 698.6
Oil of resin 20 940
Oil of turpentine 20 870
Oil, lubricating 20 900
Oiticica oil 20 972
Olive oil 20 911
Oxygen (liquid) -183 1140
Palm kernel oil 15 922
Palm oil 15 914
Palm olein 40 910
Palm stearin 60 884
Paraldehyde 20 994
Paraffin 800
Palmitic Acid 25 851
Peanut oil 20 914
Pentane 20 626
Pentane 25 625
Perchlor ethylene 20 1620
Perilla oil 25 924
Petroleum Ether 20 640
Petrol, natural 60oF (15.6oC) 711
Petrol, Vehicle 60oF (15.6oC) 737
Phenol (carbolic acid) 25 1072
Phosgene 0 1378
Phytadiene 25 823
Phulwara butter 100 862
Pinene 25 857
Pine nut oil 15 919
Poppy seed oil 25 916
Pork lard 20 898
Propanal 25 866
Propane -40 493.5
Propane, R-290 25 494
Propanol 25 804
Propylamine 20 717
Propylenearbonate 20 1201
Propylene 25 514.4
Propylene glycol 25 965.3
Pyridine 25 979
Pyrrole 25 966
Rape seed oil 20 920
Resorcinol 25 1269
Rice bran oil 25 916
Rosin oil 15 980
Salmon oil 15 924
Sardine oil 25 915
Sea water 25 1025
Seaflower seed oil 15 924
Shark liver oil 25 917
Sheanut butter 100 863
Silane 25 718
Silicone oil 25 965 – 980
Sodium Hydroxide (caustic soda) 15 1250
Sorbaldehyde 25 895
Soybean oil 20 920
Stearic Acid 25 891
Stillinga seed kernel oil 25 937
Sulfur dichloride 1620
Sulfuric Acid 95% concentration 20 1839
Sulfurus acid -20 1490
Sulfuryl chloride 1680
Sugar solution 68 brix 15 1338
Sunflower seed oil 20 919
Styrene 25 903
Tall oil 25 969
Terpinene 25 847
Tetrahydrofuran 20 888
Toluene 20 867
Trichlor ethylene 20 1470
Triethylamine 20 728
Trifluoroacetic Acid 20 1489
Tung oil 25 912
Turpentine 25 868.2
Ucuhuba butter oil 100 870
Vernonia seed oil 30 901
Walnut oil 25 921
Water, heavy 11.6 1105
Water – pure 4 1000
Water – sea 77oF (25oC) 1022
Whale oil 15 925
Wheatgerm oil 25 926
o-Xylene 20 880
m-Xylene 20 864
p-Xylene 20 861

References

  1. https://www.astm.org/Standards/D4052

  2. https://www.britannica.com/science/density

  3. DOWSON, D., JONES, D. Lubricant Entrapment between Approaching Elastic Solids. Nature 214, 947–948 (1967). https://doi.org/10.1038/214947b0

The article is written by Riya Veluri, an editorial team member of Industrial Lubricants. After her graduation, Riya works as a website developer & SEO specialist in Lubrication & Tribology Industry & writes technical articles on Lubricants, Lubrication, Reliability & sustainability.