How to Use an Ubbelohde Viscometer? By Zonwon Tech

An Ubbelohde type of viscometer is an instrument that measures viscosity using a capillary based method.  This particular type is recommended for measuring solutions with high viscosity because the values it obtains are separate from the total volume.  It was invented by Leo Ubbelohde (1877-1964) and bears his name.  The viscosity of a fluid is the measure of its resistance to deformation.  For example, as water spills out of a pitcher, it changes shape.  Honey would do the same but at a more gradual rate.  Therefore, water has a much higher viscosity than honey, for instance.  For liquids, the viscosity refers to “thickness.”  There are many different types of glass capillary viscometers because no single measuring instrument is suited for all viscosity determinations.  

However, Ubbelohde viscometers are all U-shaped glassware with a reservoir on one side and a measuring bulb with a capillary on the other.  Individual analysts have their preferences about which one to use.  Once you have the instrument that is suited to your own needs, follow the instructions below for how to use an Ubbelohde Viscometer. 

Step One

First, charge the viscometer with the fluid you are determining.  Put it into the first, large tube: the reservoir.  Be sure it is between the two lines on the tube so that the amount of liquid charged will not obstruct the Air Tube during use.  

Step Two

Next, connect clean, dry rubber tubing to the Timing Tube and the Air Tube, and place the viscometer in a temperature controlled liquid bath.  Here, the capillary must be vertical.  The sample liquid must come to the same temperature in the bath, and this will take about 20 minutes.  

Step Three

Next, seal off the rubber tubing that is connected to the air tube and gently suction it to the Timing Tube until the liquid reaches about 5 mm above the upper Timing Mark.  Hold the liquid at this level by sealing the tube.  Make sure that this point is at least 2cm below the bath liquid level.  

Step Four

Now, release the air tube to allow the liquid to fall away from the bottom of the capillary tube.  If the charge has a high viscosity, it is likely necessary to apply pressure to the air tube so that the liquid falls away from the bottom of the capillary tube.  

Step Five

Next, release the timing tube and allow the liquid to flow.  Measure the flow time in seconds for the bottom of the meniscus to pass from the top edge of the top Mark Line to the top edge of the Mark Line below it.  The time it takes for the liquid to pass through the two calibrated marks is a measure for the viscosity.  

Note, this device also has a third arm extending from the end of the capillary and open to the atmosphere.  This is so that the pressure head only depends on a fixed height and not the total volume of liquid, making the instrument a preferred measuring choice.  

How to Choose and Use Viscometer ?

Zonwon Tech,IVS300-2 automatic viscometer

How to choose the right viscometer?

There are variety of classification of the viscometer,it can be divided into 3 types with the mode of operation , capillary type,rotary type and vibration type . So how to choose the correct viscometer and how to use it?

4 parameter when select the viscometer:
1. Temperature, temperature controllable, temperature range?
2. The range of viscosity,the viscosity range of your sample.
3. Need to be measured at a fixed shear rate, or fixed speed, rotor, etc.
4. Sample quantity, whether the sample is expensive, whether the need to control the amount of samples.

Zonwon Tech, IVS300-6 automatic viscometer

How to use the viscometer?

1. The machine must maintain the level of state.
2. The rotor sample to avoid air bubbles, otherwise the measured viscosity can be reduced, the method is to avoid the rotor inclined to sample, and then install the rotor, the rotor can not touch the wall of the cup and the bottom of the cup, the scales are measuring samples must be No.
3. When measuring different samples, the rotor must be kept clean and dry, if there are other samples of the rotor or the remaining water after cleaning, will affect the accuracy of the measurement
4. Acid (PH) maximum of not more than 2, if the acidity is too large to be used special rotor, when using ULA to determine the good quality (16ml)
5. According to the determination of the viscosity of liquid viscosity range selection standard, and in front of the instrument or the viscometer rheometer validate each use, or regular check, to ensure measurement accuracy. BROOKFIELD can provide the scope of the viscosity of the Newton fluid properties of silicone oil or oil standard, the accuracy of 1%, the standard viscosity of the liquid is recommended for a period of one year since the opening.
6. The value to be more stable in the numerical value, otherwise there will be a large numerical error
7. The choice of the rotor, depending on the viscosity of the sample was measured and the number of rotors of the measurement range is the closest, on the election number.
8. The rotor is connected to use the left hand and gently pinch the mandrel (host), right hand rotation of the rotor, this operation is to protect the body of the spindle and the hairspring, it can prolong the life of the instrument.

Issued by Hangzhou Zonwon Technology Co.,Ltd

Ubbelohde viscometer

An Ubbelohde type viscometer or suspended-level viscometer is a measuring instrument which uses a capillary based method of measuring viscosity.^[1] It is recommended for higher viscosity cellulosic polymer solutions. The advantage of this instrument is that the values obtained are independent of the total volume. The device was developed by the German chemist Leo Ubbelohde (1877-1964).

ASTM and other test methods are: ISO 3104, ISO 3105, ASTM D445, ASTM D446, ASTM D4020, IP 71, BS 188.^{[2][citation needed]}

The Ubbelohde viscometer is closely related to the Ostwald viscometer. Both are u-shaped pieces of glassware with a reservoir on one side and a measuring bulb with a capillary on the other. A liquid is introduced into the reservoir then sucked through the capillary and measuring bulb. The liquid is allowed to travel back through the measuring bulb and the time it takes for the liquid to pass through two calibrated marks is a measure for viscosity. The Ubbelohde device has a third arm extending from the end of the capillary and open to the atmosphere. In this way the pressure head only depends on a fixed height and no longer on the total volume of liquid.

Determination of viscosity[edit]

The determination of viscosity is based on Poiseuille's law:

${\displaystyle {\frac {dV}{dt}}=v\pi R^{2}={\frac {\pi R^{4}}{8\eta }}\left({\frac {-\Delta P}{\Delta x}}\right)={\frac {\pi R^{4}}{8\eta }}{\frac {|\Delta P|}{L}},}$

where t is the time it takes for a volume V to elute. The ratio ${\displaystyle {\frac {dv}{dt}}}$ depends on R as the capillary radius, on the average applied pressure P, on its length L and on the viscosity η.

dynamic

The average pressure head is given by:

${\displaystyle \Delta P=\rho g\Delta H\,}$

with ρ the density of the liquid, g the Standard gravity and H the average head of the liquid. In this way the viscosity of a fluid can be determined.

Usually the viscosity of a liquid is compared to a liquid with an analyte for example a polymer dissolved in it. The relative viscosity is given by:

${\displaystyle \eta _{r}={\frac {\eta }{\eta _{0}}}={\frac {t\rho }{t_{0}\rho _{0}}},}$

where t₀ and ρ₀ are the elution time and density of the pure liquid. When the solution is very diluted

${\displaystyle \rho \simeq \rho _{0}\,}$

the so-called specific viscosity becomes:

${\displaystyle \eta _{sp}=\eta _{r}-1={\frac {t-t_{0}}{t_{0}}}.\,}$

This specific viscosity is related to the concentration of the analyte through the Intrinsic viscosity [η] by the power series:

${\displaystyle \eta _{sp}=[\eta ]c+k[\eta ]^{2}c^{2}+\cdots \,}$

or

${\displaystyle {\frac {\eta _{sp}}{c}}=[\eta ]+k[\eta ]^{2}c+\cdots ,\,}$

where ${\displaystyle {\frac {\eta _{sp}}{c}}}$ is called the viscosity number.

The intrinsic viscosity can be determined experimentally by measuring the viscosity number as function of concentration as the Y-axis intercept.

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