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Applications – Lubricants, oils and fuels

Absolute viscosities and interfacial properties – precisely measured according to international standards

The change in viscosity due to temperature fluctuations is of importance in those places where oils and liquids are produced, pumped, and moved. The minimization of friction losses due to the selection of suitable oils is essential when it comes to the design of machines and pneumatics. As mentioned before, capillary viscometry is the most precise and strictly standardized method to measure absolute viscosities.

Measuring routines need to be executed efficiently, quickly, with absolute safety, and reproducibly at any time. With the modular concept of LAUDA, system configurations can be put together which combine the functionalities required for the respective purpose. Important indicators of oil quality, for example, to check the deterioration of transformer oils, are also the surface tension (ST) to air, but particularly the interfacial tension (IT) to water or aqueous solutions. The surface/interfacial tension also serves to characterize additives for fuels and lubricants or to analyze tertiary crude oil production and all sorts of surfactants, e.g. emulsifiers, wetting agents, etc. Alongside the conventional lamellae tension methods of Du Noüy and Wilhelmy, LAUDA provides the drop volume and bubble pressure methods with which adsorption processes of amphiphilic additives or aging products can also dissolve over time on interfaces.

Application examples

Absolute viscosities:

  • Lubricants and fuels
  • Oil production and transport
  • Silicone and silicone oils
  • Waxes, resins and polyols

Interfacial tensions:

  • Insulating oils
  • Additives for crude oil production and fuels
  • Surfactants, e.g. wetting


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LAUDA Measuring Instruments Brochure (8.2 MB)

  LAUDA viscometer advantages Your benefits
  • ASTM D445 DIN 51562
  • Intuitive measuring principle
  • Unrivalled precision
  • Constant calibration not dependent on temperature
  • Up to eight parallel measurement positions
  • Compatibility
  • Easy, affordable execution with stopwatch
  • Better than 0.3 per cent guaranteed
  • Only one capillary constant from -40 up to 200 °C
  • Acceleration of the process
  • International comparability independent of the measuring device
  • Calculation of the viscosity index according to ASTM D 2270/ISO 2909
  • Automatic control of the temperature
  • Extreme measurement range from -60 up to 200 °C
  • Comparison of the specifications with current figures from the quality check
  • Work-free periods can be used for long-term measurements
  • Complete viscosity scan possible at all application temperatures
  LAUDA tensiometer advantages Your benefits
  • Sensitive to amphilic molecules
  • Standardized sensors
  • Ring method TD, interfacial tensions
  • Drop volume method
  • Computer software running Windows
  • Low concentration of impurities, additives and aging products detectable
  • International comparability
  • Provide values in thermodynamic equilibrium
  • Provides additional information on adsorption on interfaces
  • Flexible experiment running, also for research tasks
  • Intuitive operation, high degree of flexibility

Lubricants and fuels

Viscosity index and kinematic viscosities of SAE/ISO motor oils at application temperatures

The Viscosity Index VI is used as a measure for the temperature dependence of the viscosity with lubricating oils in the area of application. In accordance with ASTM D 2270 or ISO 2909, this is determined from the kinematic viscosities at 40 and 100 °C. Here, oil with the least change in viscosity was assigned a VI value of 100, while that with the largest change was assigned a VI value of 0. With modern synthetic oils or multi-purpose oils the viscosity index can be increased significantly above 100 using additives (VI improvers). The higher the viscosity index of an oil, the less its viscosity changes at different temperatures. This makes the operation of engines, for example, less subject to climatic conditions. In summer, the lubrication effect of such oils is still sufficient, while in winter the oils are not too viscous.

Depending on the sample rate, the LAUDA PVS system provides tailored solutions. As such, a PVS system in a PV 15 viscothermostat can be used to program the necessary temperatures of 40 and 100 °C while measuring the viscosities of the same samples one after the other. The two values, and thus the viscosity index, can be determined significantly quicker when measuring stands in two thermostats are used at fixed temperatures of 40 and 100 °C. This way, oils can be measured using a PVS 1/8, each with four measuring stations at 40 and 100 °C in two thermostats along the entire viscosity range. If equipped accordingly, the glass capillary viscometers are then cleaned and dried automatically.

Typical configuration

Measuring system PVS 1/8 with four + four measuring stands for parallel measuring of viscosities at 40 and 100 °C and calculation of the VI index with automatic viscometer cleaning for oils from 2 to 1,000 mm2/s

  • PVS 1/8 control unit
  • Eight measuring stands S 5
  • Software module VID-DLL
  • Four VRM 4 cleaning modules for cleaning the Ubbelohde with two cleaning agents
  • Two PV 24 viscothermostats (one at 40 °C with water and DLK 10 cooler and one at 100 °C with thermostating oil)
  • Two Ubbelohde glass viscometers each of sizes Ic, II, IIc, III (with aspirating tube)
  • Dosing syringes for filling the viscometers

Recommended standards

  • ISO 2909
    Petroleum products – Calculation of viscosity index from kinematic viscosity
  • ASTM 2270
    Standard Practice for Calculating Viscosity Index From Kinematic Viscosity at 40 and 100 °C
 

Lubricants and fuels

Low-temperature behavior (paraffin formation) of motor oils, diesel, and kerosene

In modern aviation, extreme requirements are made of both the technology and the materials. At the flying altitudes of today‘s jets at 10,000 meters, temperatures down to -60 °C are common. Luckily, it is not the passengers who feel the effects of this, but the fuel in the tanks and piping as well as the motor and drive lubricants. As such, it needs to be ensured that their viscosity does not increase to a level over a critical value or that the paraffin begins flocculating as a result of the extreme temperature changes during long flights. For this reason, tests on the viscosity are carried out in the lab in realistic conditions. Of course, the same applies to fuels, and motor and hydraulic oils which are used in polar regions, meaning that viscosity measuring down to -40 °C is also relevant here.

In connection with the powerful DLK 45 through-flow cooler or the Proline RP 890 cooling thermostat, the PVL 15 viscothermostats for two measuring stations and PVL 24 for four measuring stands are designed for working at temperatures down to -40 or -60 °C. The four-fold insulating glass prevents the windows from fogging up and makes sure the viscometers can be seen clearly. With the PVS system, kinematic viscosities at these extreme temperatures can be measured conveniently. The viscometer is cleaned automatically too. The ambient air used in measuring and cleaning can be dried using a connected cooling trap so as to avoid any freezing, especially of the measuring capillaries.

Typical configuration

Measuring system PVS 1/2 with two measuring stands for parallel measurement of viscosities at temperatures down to -40 °C with automatic viscometer cleaning and drying trap for kerosene and other fuels.

  • PVS 1/2 control unit
  • Two measuring stands S 5
  • A VRM 4 cleaning module for cleaning the Ubbelohde with two cleaning agents
  • PVL 15 viscothermostat connected to a powerful DLK 45 cooler
  • Two Ubbelohde glass viscometers each of sizes Ic, II (with aspirating tube)
  • Cooling trap for drying and cleaning the used ambient air

Recommended standards

  • ASTM D 2532
    Standard Test Method for Viscosity and Viscosity Change After Standing at Low Temperature of Aircraft Turbine Lubricants
  • ASTM D 445
    Standard Test Method for Kinematic Viscosity of Transparent and Opaque Liquids (and Calculation of Dynamic Viscosity)

 

Insulating oils

Kinematic viscosity and interfacial tension of transformer oils

Transformers are among the most important elements in energy supply. Here, transformer oils are used for insulating and cooling. However, unusual strains, like for example, transient overvoltage, overheating in emergency operation, or disruption to cooling, lead to accelerated deterioration of the oils and a reduced life-span. With the oxidation and deterioration of oils which are heavily stressed or are in use for a number of years, insoluble and polar components build up. By measuring the interfacial tension this build-up in the oil can be detected. This helps to classify the deterioration and remaining life-span of the oil. In the lab report, the interfacial tension is indicated in mN/m. If their value compared either to fresh oil or to the previous sample has decreased significantly, the oil has deteriorated, which means that regeneration or an oil change is necessary. Due to their compact design and intuitive operation using the separate Command remote control, the LAUDA ring tensiometers TD 1 C and TD 3 are best suited for mobile use on location as well.

In Arctic regions, the temperature in a deactivated transformer can sink to -40 °C. Here, the viscosity increases dramatically, sometimes accompanied by paraffin flocculating. This changes the insulating properties with the risk of damage to the transformer. As such, the viscosity at very low temperatures also needs to be measured when formulating the oils. LAUDA provides tailored configurations for this purpose.

Recommended equipment:

Automatic tensiometer – Ring method according to Du Noüy

  • TD 3

Semi-automatic tensiometer – Ring method according to du Noüy

  • TD 1 C

Each with:

  • PTT Peltier thermostating unit
  • Measuring ring (2-legged)
  • Density measurement set
  • Calibration weight
  • Printer and/or data transfer software for PC (TD 3 only)

Suitable configuration for viscosity measurements at low temperatures of -40 °C see above.

Recommended standards

  • ASTM D 971
    Standard Test Method for Interfacial Tension of Oil Against Water by the Ring Method
  • DIN EN 14370
    Surface active agents – Determination of surface tension

 

Oil production

Recovery rate in tertiary oil production with surface active substances

The recovery rate refers to the actually retrieved portion of the total amount of crude oil available at the site of an oil field. In order to increase this portion, the efficiency of so-called tertiary production needs to be improved if relatively simple measures like the injection of water or gas (secondary production) do not lead to any satisfactory increase in the recovery rate. With tertiary production („Enhanced Oil Recovery“ EOR), special measures are taken to further improve recovery from an oil source. An important method of EOR is the injection of aqueous solutions in connection with surface active materials (surfactants).

With the LAUDA drop volume tensiometer TVT 2, along with the surface tension of liquids, the interfacial tension between oil and the rinsing agent can be specified precisely. Here, the dynamic, drop-age-dependent interfacial tension (IT) can be determined down to 0.1 mN/m from the volume of rising crude oil drops. The IT is a measure of the emulsifiability of the oil and thus of the oil‘s capacity to absorb the rinsing agent. The aim here is to adapt the agent in such a way that the crude oil separates significantly more easily from the solid matter (rocks or similar) and moves more freely through the often very narrow hollow subterranean passages as an emulsion. With the TVT 2, measurements between approx. 60 and 70 °C can be made, which often correspond to the conditions within the drill hole

Recommended equipment:

PC-controlled TVT 2 drop volume tensiometer with RE 415 S thermostat and reverse measuring set for rising drops, various syringes and needles for surface and interfacial tension oil measurements

  • TVT 2 E
  • TVT 2 M

with:

  • Syringe 2.5 ml
  • Needle 1.039 mm
  • Software for Windows PC
  • Reverse measuring set
  • RE 415 S thermostat with Pt100 probe and RS 232 interface
  • Syringes 5 ml and 1 ml
  • Standard needles set

Recommended standard

  • ISO 9101
    Surface active agents – Determination of interfacial tension – Drop volume method

 

Oil transport

Pumpability of crude oils

Oil pipelines are the arteries of modern civilization. Over thousands of kilometers, through mountains and valleys, they bring crude oil from the ports or production sites to the refineries. As such, the Transalpine Pipeline (TAL) connects the oil harbor of Trieste with refineries in Karlsruhe and Ingolstadt in Germany, crossing the main Alpine ridge at a tunnel height of 1,500 meters. The oil temperature in the different sections between the pumping stations, where the crude oil‘s transportation is constantly monitored, is correspondingly varied and weather-dependent. The flowability and thus the viscosity of the pumped crude oil is a decisive factor in this. This, in turn, is heavily dependent on the temperature fluctuations as a result of the heights to be surmounted and the prevailing climates, which need to be taken into consideration when calibrating the pumps in the pump stations.

To record viscosity temperature characteristics, LAUDA provides easy-touse PVS systems with thermostat programming and automatic viscometer cleaning as well as affordable compact systems like the iVisc. The compact Viscocool 6 thermostat is suited as constant temperature equipment.

Typical configuration

PVS system with an S 5 measuring stand and temperature programming of 15 to max. 80 °C in the Viscocool 6 viscothermostat with Peltier cooling

  • PVS 1/2 control unit
  • Software TEMP-DLL
  • Measuring stand S 5
  • Ubbelohde viscometer type lc, ll
  • Viscocool 6 viscothermostat and cover plate
  • RS 232 plug-in for Viscocool 6
  • PVS 1 system with an S 5 measuring stand and temperature control of 10 to 40 °C in the Viscocool 6 viscothermostat with Peltier cooling

iVisc in the Viscocool 6 viscothermostat with Peltier cooling (manual temperature setting)

  • iVisc
  • Ubbelohde capillaries of types Ic and II
  • Viscocool 6 viscothermostat and cover plate

Recommended standard

  • ASTM D 445
    Standard Test Method for Kinematic Viscosity of Transparent and Opaque Liquids (and Calculation of Dynamic Viscosity)

 

Waxes, resins, silicone and polyols

Absolute, kinematic, and dynamic viscosities of highly viscous liquids and their temperature dependency

Waxes melt at over 40 °C without decaying and demonstrate significantly decreasing viscosity above the melting point. Synthetic waxes and resins are recovered mainly from crude oil. They are used to manufacture lacquers, soaps, drugs, and turpentine. Liquid silicone is a clear, colorless, neutral, odorless, and hydrophobic liquid with a wide range of viscosity. Among other things, it is used as an anti-foaming agent, hydraulic liquid, mold-release agent, to make items water-repellent, and as an anti-friction agent and lubricant. Silicone liquids of higher viscosity are used as liquids in viscose coupling, as electrical insulating material, heat transfer liquids, and as an absorptive agent. Also referred to as polyols, the polyalcohols are usually highly viscous to solid at room temperature. Polyvinylalcohols (PVA) are reactive, nonhazardous, very good film formers, and serve as thickeners for glues, salves, and emulsifiers, for coating packaging and as filling material and additives for lacquers, motor oils, etc. What the material groups mentioned above have in common is their extremely wide range of viscosity and the strong changes at different temperatures.

Along with precise viscosity measurement and thermostating across the entire range of application, the LAUDA PVS system also offers the automation convenience necessary in shift work. Highly viscous samples can be dosed automatically, diluted with suitable solvents, and extracted. Afterwards, the viscometers are cleaned and dried without having to be taken out of the thermostat.

Typical configuration

PVS 1/4 system with four S 5 measuring stands in the Viscotemp 24 viscothermostat from 20 to 100 °C, manual dosing using syringe, automatic viscometer cleaning for the viscosity range of 2 to a maximum of 3,000 mm2/s

  • PVS 1/4 control unit
  • Software module TEMP-DLL
  • Four S 5 measuring stands
  • Ubbelohde viscometer type Ic, II, III, IV (with tubing for filling, diluting, and extraction)
  • Two VM 4/HT cleaning modules
  • Two external VRP pumps
  • Special sample locks for samples with high viscosity
  • Viscotemp 24 viscothermostat and cover plate
  • RS 232 interface for Viscotemp 24
  • External DLK 10 cooler for T<40 °C

Recommended standards

  • ASTM D 445
    Standard Test Method for Kinematic Viscosity of Transparent and Opaque Liquids (and Calculation of Dynamic Viscosity)
  • DIN 51562
    Measurement of kinematic viscosity by means of the Ubbelohde viscometer