Viscosity Measurement
Viscosity Measurement
(OP)
I read in a recent Control magazine (April 2003) that it is possible to calculate viscosity of a fluid by using a coriolis flowmeter and differential pressure. Does anyone have experience doing this and is it possible with crude oil?
Thanks in advance.
Joe Malter
Thanks in advance.
Joe Malter





RE: Viscosity Measurement
If you have a Newtonian fluid (water, oil, beer) and laminar flow, YES you can calculate viscosity from pressure drop and flow.
The whole trick is that pressure drop is linear with pressure differential divided by flow.
viscosity = C * dP / flow [Engineering Unit]
I know Endress + Hauser has Coriolis mass-flow meters in protoype which give viscosity as an output.
Post your e-mail and I can sent you a writing on it.
Cheers,
MVD
http://www.pressure-drop-calculator.com/
RE: Viscosity Measurement
The new Endress and Hauser viscosity measurement system is based, i believe, on the change in signal amplitude according to the viscosity of the fluid.
Micromotion used to, and possibly still do in some cases, supply their mass meter with a dP cell to measure the pressure drop. Pressure drop isthen a function of the viscosity at any given flow rate. (see. www.viscometer.com)
The problem with process viscosity measurement, when you are talking about crude oil, is that temperature is avariable and refinery measurements are analytical. the process capilary viscometer has held its position as the industry standard for viscosity measurement for over 40 years because of the difficulty of making process analytical viscosity measurements. Most process viscometers are suited to behavioural measurements. The difference is that a behavioural measurement is where you need the viscosity at the process temperature e.g. fuel oil heating for atyomisation control and analytical measurement requires the viscosity at a reference temperature. In pipe line applications the reference temperature posted by the pipe line operators is a moving target!. The problem is that the point at which you measure viscosity is at a different (variable) temperature to the pipeline reference temperature. To make suitable online contiuous process viscosity measurment requires a sophisticated measurement system which is not just a viscometer. Solartron Mobrey (www.solartronmobrey.com) usually use a system based on two viscometers operating at different temperatures to map the temperature Vs viscosity relationship (continuously) and then calculate the viscosity at the reference temperature using the ASTM D341 calculation. This gives favourable results compared to a lab viscometer (ASTM D445) which is a capillary immersed ina temperature bath operating at constant temperature. These lab measurements are usually analysed ststistically (API 555)... in some refineries this means unning as many as 8 parralele lab measurements to obtain a mean value. The lab capillary relies on the same flow rate is a function of viscosity theory as the mass flow meters with dP transmitters except they operate as apurose designed instrument under precisely controlled conditions. Once you move away from this you are making compromises.
However, i have assumed you are wanyiong to look at the quality of the crude oil. If you are wanting a simple identity of the crude for, say, adding the correct amount of drag reducer then you can use quite simple viscosity measurement techniques.
RE: Viscosity Measurement
I'm an instrument and controls guy and when I saw the possibility of calculating the viscosity by installing a DP transmitter across our flow meter I thought I had something. Now I'm trying to see if it will work and give us meaningful results.
Joe Malter
jmalter@pipesys.com
RE: Viscosity Measurement
Can anybody help me with some information on how to build a fast and effective instrument, that can help me to calculate viscosity (home made viscometer).
RE: Viscosity Measurement
Readings are instantaneous. You may even be able to get a rough temperature correction calculation from it ie. to estimate the viscosity at the mean pipe line temperature. It is also used for product differentiation where drag reducers are doesd according to which crude is in the pipeline.
RE: Viscosity Measurement
RE: Viscosity Measurement