14 Analytical Instrumentation


Petroleum – Density Measurement is Uncovering Treasures Below the Earth’s Surface


Characterisation of Oils and Petroleum Products - Whatever the Viscosity


Crude oils and petroleum products are complex mixtures. One of the most important properties for their characterisation is the measurement of their density (rho) or specific gravity (SG).


The Anton Paar density meters rise to the challenge of measuring the density of a wide range of petroleum products in numerous measurement situations in this industry.


This includes gaseous products, liquids with different viscosities and solids. Different density meter models are available for different requirements. The infobox lists the technical specifications of Anton Paar’s range of density meters.


Liquid samples with low viscosities can usually be measured directly. Transferring samples to the lab for quick quality checks becomes a thing of the past with the intrinsically safe portable density meter DMA 35 Ex Petrol – the measurement is performed directly on-site.


For measurements in the lab requiring temperature control of the sample – e.g. heating the sample to reduce the viscosity – density meters are available from the compact and low-price DMA 500 to the more accurate density meters of the DMA Generation M series.


The Generation M density meters combined with a heated sample changer heat, fill and measure highly viscous samples fully automatically.


Like the other sample changers of the Anton Paar Xsample series, the heated versions Xsample 352 H and 452 H allow multiple measurements from the same vial as well as recovery of the sample after the measurement.


Measurement is completed within 1 to 4 minutes and the amount of sample required is low (typically 3 mL). The amount of required cleaning solutions is also kept to a minimum.


Infobox


DMA 35 Ex Petrol DMA 500


DMA 4100 M DMA 4500 M DMA 5000 M


DMA HP DMA HPM


Measuring Range (kg/m3


)


0 to 3000 0 to 3000


0 to 3000 0 to 3000 0 to 3000 Measurement under pressure


Samples with high viscosities (e.g. up to 35,000 mPa.s at 20 °C) or samples with volatile components are best filled into the density meter under pressure.


These requirements can be realised with a DMA HP or DMA HPM, capable of measuring sample at pressures up to 1400 bar (20,300 psi) and temperatures up to 200 °C (473 K).


In the petroleum industry density is frequently quoted at 15 °C, 20 °C or 60 °F (= 15.56 °C), although the measurement is performed at a higher or lower temperature.


The conversion of the measured density at any temperature into the density at 15 °C or 60 °F is carried out automatically within the density meter.


Gaseous


DMA HP DMA HPM


Liquid (C5 - C17)


DMA 35 DMA 500 DMA 4100 M DMA 4500 M DMA 5000 M


Solid


DMA HP DMA HPM


Play it safe!


DMA 35 Ex Petrol is the only portable density meter with Ex certification (Ex marking II 2 G Ex ib IIC T4). This means that safe operation is ensured, even when explosive or flammable gases are present in the measuring environment.


Viscosity 1 mPa.s at 20 °C 35,000 mPa.s at 20 °C 15,000 mPa.s at 80 °C


Anton Paar density meters meet international standards The DMA 4100 M, DMA 4500 M and DMA 5000 M density meters provide density measurements compliant with the standards ASTM D 4052-09, ASTM D 5002-99 and DIN ISO EN 12185. These standards describe test methods for density determination with an oscillating U-tube in the petroleum industry.


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Coming with a special housing resistant to petroleum samples, it is typically used at refineries, on tankers, storage sites and filling and loading stations for QC checks of crude oils as well as refined products - directly on-site.


Temperature Range


(°C) 0 to +40 +15 to +40 0 to +95 -10 to +200 -10 to +200


Pressure Range (bar)


not relevant 0 to 3


0 to 10 0 to 700 0 to 1400


Accuracy (kg/m3


)


1.0 1.0


0.1 0.05 0.005


0.1, 0.05 or 0.005 01. to 0.01


August / September 2011 • www.petro-online.com


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