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What I learned in week 12?, Patthiya Srimahaprom 61010789 - Coggle Diagram
What I learned in week 12?
Analytical Instrumentation
Viscosity measurement
Efflux cup viscometers: (Sayboltviscometer)
Used for fieldwork to measure the viscosity of oil, syrups, vanish, paint, and bitumen emulsions.
Efflux time
Measure through a fixed orifice at the bottom of a cup to represent the viscosity of fluid
Testing petroleum products
Types of orifices
Furolorifice
Road-oil orifice
Universal orifice
Most commonly used
Falling ball viscometers
For the measurement of high viscosity fluids.
Made by timing the ball of the ball through the accurately calibrated distance between two marks on the glass tube
Capillary viscometer:(Laboratory type)
Liquid passing through a capillary tube is directly proportional to its absolute viscosity
Cannon-Fenske Routine
Works well if the liquid to be measured is transparent
Ubbelohde
Suspended level viscometers possess the same viscometer constant at all temperatures
Reverse Flow Viscometers
Designed for testing opaque liquids.
Dilution Viscometers
Estimates of large polymer molecules can be obtained from kinematic viscosity measurements of dilute solutions of the polymers
Vacuum Viscometers
When liquids are too viscous to flow readily under gravity, vacuum viscometers may be used to measure viscosity
Rotational viscometers
Use a spring to measure the torque required to rotate a spindle immersed in a sample liquid
Converts the torque value into viscosity
viscosity measured depends on the geometry of the spindle (shape,size) and the speed of rotation
Spindle geometries.
Cylindrical spindles
Cone spindles
Disc spindle
Vane spindles
T-bar spindles
spiral spindles
Larger discs are used to measure lower-viscosity fluids
Humidity measurement
Hair hygrometer & hair hygrograph
Change of length of certain organic or synthetic fiber when these are exposed to a moist atmosphere.
Electronic hygrometer
Capacitive type
Sensor
Hygroscopic dielectric material sandwiched between a pair of electrodes forming a small capacitor
Use a plastic or polymer as the dielectric material
Very linear, measure RH from 0 to 100%, and also need regular calibration
Resistive type
Sensor element changes in response to humidity changes, and the capacitance changes are extracted as electrical signals
Find difficulty in measuring low values (below 5%RH)
Temperature effects the properties significantly
The change is impedance is too high
Psychrometer
2 thermometers
Measures the actual air (dry-bulb) temperature
The other one is covered with a wet-bulb temperature
Sling Psychrometer
Simple design, low cost, and portability
Construct of two thermometers secured to a frame
Aspirating Psychrometer
Mechanized unit, compact and easily transportable
Accuracy, less chance for procedural error, and usefulness in confined areas
Chilled-mirror dewpoint hygrometer
Noting the temperature of polished metal surface (mirror) when the first traces of condensation (fogging) appear
Used to determine dew point temperature
Lithium chloride dewpoint hygrometer (Dewcel)
Used to determine the dewpoint
Temperature sensor covered with wicking soaked in a solution of lithium chloride, and over which is wound a pair of bare gold wires
Current flow occurs via lithium chloride solution and increases the temperature of the solution until the vapor pressure is equilibrium with the ambient air
pH measurement
Colorimetric pH measurement
Measure the pH of a solution is by color
Potentiometric
Use the electrochemical
Special pH-sensitive electrodes
Generate a voltage dependent upon the pH value of that solution
Hydrogen ion exchange between the process liquid solution and a buffer solution inside the bulb formulated to maintain a constant pH value
Reference electrode
Measurement electrode
Always keep the glass electrode wet
Level measurement
Capacitance
Used in filler bowls, oil reservoirs , and short chemical storage vessels
Capacitance level sensor
Two plates separated by an insulator
When process level increases, capacitance increases between the rod and the vessel walls
For conductive liquids
It cannot be used as the dielectric (insulating) medium of a capacitor
Probes are coated with plastic or some other dielectric substance
For nonconductive liquids
Used as the dielectric itself
Metal wall of the storage vessel forming the second
capacitor plate, Probe is just a bare metal cable or rod.
Applications & limitations
Most reliable form of electronic level measurement for interface applications involving layers of multiple conductive and nonconductive liquids
Quick response speed and the wide variety of media that it can measure
It only works with a ground reference point
Patthiya Srimahaprom 61010789