Related Experiment Video
Updated: Jan 21, 2026
08:02
Fabricating High-viscosity Droplets using Microfluidic Capillary Device with Phase-inversion Co-flow Structure
Published on: April 17, 2018
11.0K
Experimental study on factors affecting the end effect in gas viscosity measurement using capillary-tube viscometer
Xin Fang1, Xiang'an Yue1, Joseph Y Fu1
1State Key Laboratory of Petroleum Resources and Engineering, Key Laboratory of Petroleum Engineering Ministry of Education, China University of Petroleum, Beijing 102249, China.
The Review of Scientific Instruments
|August 3, 2019
Summary
This study introduces an improved capillary-tube viscometer to minimize end effect errors in viscosity measurements. By identifying threshold parameters, researchers developed an end-effect-free method for accurate gas viscosity determination.
Area of Science:
- Fluid Dynamics
- Physical Chemistry
- Metrology
Background:
- Capillary-tube viscometers are widely used for viscosity measurement due to their simplicity and adaptability.
- End effect corrections in capillary-tube viscometry introduce significant uncertainty in measurement results.
- Accurate viscosity measurement is crucial for various scientific and industrial applications, especially under high pressure.
Purpose of the Study:
- To investigate factors influencing the end effect in capillary-tube viscometry.
- To develop an end-effect-free method for accurate gas viscosity measurement.
- To improve the precision of capillary-tube viscometers, particularly for high-pressure applications.
Main Methods:
- Conducted high-pressure nitrogen viscosity measurements at low flow velocities using an improved capillary-tube viscometer.
- Analyzed the influence of flow velocity (v), tube inner diameter (d), and tube length (L) on the end effect.
- Defined a viscosity deviation coefficient (Ce) and identified threshold parameters (vthreshold, dthreshold, Lthreshold) for negligible end effect.
Main Results:
- The end effect's influence decreased with lower flow velocity and tube diameter, and inversely with tube length.
- Threshold parameters were identified where the viscosity deviation coefficient approached 1.0, indicating negligible end effect.
- The developed end-effect-free viscometry method achieved results with <1.2% error compared to NIST data for nitrogen viscosity.
Conclusions:
- Established an end-effect-free capillary-tube viscometry method applicable under specific experimental conditions.
- Demonstrated the method's accuracy and reliability by achieving good agreement with NIST standard data.
- Provided insights for enhancing the accuracy of capillary-tube viscometers in high-pressure gas viscosity measurements.
Related Concept Videos
02:57Surface Tension, Capillary Action, and Viscosity
33.0K
Surface Tension
The various IMFs between identical molecules of a substance are examples of cohesive forces. The molecules within a liquid are surrounded by other molecules and are attracted equally in all directions by the cohesive forces within the liquid. However, the molecules on the surface of a liquid are attracted only by about one-half as many molecules. Because of the unbalanced molecular attractions on the surface molecules, liquids contract to form a shape that minimizes the number...
The various IMFs between identical molecules of a substance are examples of cohesive forces. The molecules within a liquid are surrounded by other molecules and are attracted equally in all directions by the cohesive forces within the liquid. However, the molecules on the surface of a liquid are attracted only by about one-half as many molecules. Because of the unbalanced molecular attractions on the surface molecules, liquids contract to form a shape that minimizes the number...
33.0K
01:18Rise of Liquid in a Capillary Tube
3.2K
When very thin cylindrical tubes, called capillaries, are dipped in a liquid, the liquid rises or falls in the tube compared to the surrounding liquid. This phenomenon is called capillary action. Capillary action occurs due to the combination of two opposing forces: the cohesive forces of the liquid, which cause it to stick to itself and form a rounded shape, and the adhesive forces between the liquid and the walls of the container, which cause the liquid to be attracted to the container walls.
3.2K
01:17Viscosity
7.2K
When water is poured into a glass, it falls freely and quickly, whereas if honey or maple syrup is poured over a pancake, it flows slowly and sticks to the surface of the container. This difference in the flow of different kinds of liquids arises due to the fluid friction between the liquid layers and the liquid and the surrounding material. This property of fluids is called fluid viscosity. In this example, water has a lower viscosity than honey and maple syrup.
The SI unit of viscosity is...
The SI unit of viscosity is...
7.2K
01:19Viscosity of Fluid
1.2K
Viscosity measures the resistance a fluid offers to flow and deformation. It results from internal friction between layers of fluid moving relative to one another. Dynamic viscosity, denoted by the Greek letter mu (μ), quantifies the force needed to move one fluid layer over another. For Newtonian fluids like water and air, the relationship between the shearing stress and the rate of shearing strain is linear, meaning their viscosity remains constant regardless of the applied stress.
1.2K
01:21Voltammetry: Factors Affecting Measurements
534
A current produced due to the redox reactions of the analyte at the working and auxiliary electrodes is called a faradaic current. The reaction can be divided into two types. The current generated due to the reduction of the analyte is called cathodic current, and it carries a positive charge. In contrast, the current produced by analyte oxidation is known as an anodic current, and it has a negative charge. The applied potential at the working electrode determines the faradaic current flow, and...
534
01:20Gas Exchange and Transport
76.6K
Gas exchange, the intake of molecular oxygen (O2) from the environment and the outflow of carbon dioxide (CO2) into the environment, is necessary for cellular function. Gas exchange during respiration occurs largely via the movement of gas molecules along pressure gradients. Gas travels from areas of higher partial pressure to areas of lower partial pressure. In mammals, gas exchange occurs in the alveoli of the lungs, which are adjacent to capillaries and share a membrane with them.
76.6K