Flow Flashcards
What are the four requirements of accurate flow measurements
Safety
Efficient industrial processes
Environmental Standards
Financial Control
What are flow meters
Instruments used to measure flow in units of volume per unit time
What are the 2 categories of flow meters and their classes
Quantity- +ve displacement
Rate of flow - velocity type, differential mass type
Eg of quantity meters
Nbr
Nutting disc
Bellows type
Rotating vane type
Eg of rate of flow meters
MTVV
Magnetic Flowmeter
Turbine “
Vortex “
Variable “
What is the difference between quantity and rate of flow meters
Quantity measure volume whilst rate of flow measures the volume and time
if the flow is not steady, however, the total quantity will be represented by
f by the area
under the curve obtained by plotting the rate
of flow against time
principle of operation of differential flow meters
The principle of operation is based on the fact
that when a restriction is placed in a fluid
stream, the fluid must move faster in order to
pass the same quantity through the pipe as
passed before the restriction was added.
What are metering pumps
positive displacement
pumps, which provide a predictable and
accurate rate of fluid flow
Concentric orifice
Central hole/orifice for clean fluids
ie liquid no gas bubbles
Gas no liquids
Segmental
Another of suspended material not abrasive
what are meters
mir
devices used to
measure, record, and indicate the value of a
measured variable.
Archimedes principle
Any object that is partially or completely submerged in a fluid experiences an upward buoyant force equal to the weight of the fluid it displaces.”
Categories of flow measurement
Continuous level measurement
Point level measurement
Eg of continuous
GUUMM
Gauge glass
Use of floats
Ultrasonic
measure of electrical capacitance
measure of head pressure
The ball float method is a direct reading liquid
level mechanism.
The most practical design for the float is a
hollow metal ball or sphere.
However, there are no restrictions to the size,
shape, or material used.
The design consists of a ball float attached to a
rod, which in turn is connected to a rotating
shaft which indicates level on a calibrated scale
(Figure 2).
7
Orifice plate principle of operation
Is a circular metal plate with a central hole / orifice, that causes restriction in the fluid which causes the fluid to flow faster, which gives it a faster velocity and a pressure drop
Advantages of oriface plate
Easy to install and replace
relatively low price
Non-free
Advantages of oriface plate
Easy to install and replace
relatively low price
Non-free
Disadvantages of orifice plate
High pressure lost
What is concentric orifice plate and what is it used for?
An orifice plate where the hole is directly at the middle and it is used in clean fluids that is liquid with no gas or gas with no liquid
What is an eccentric orifice plate
An orifice plate has a hole at the bottom to allow solids to escape or a hole at the top to allow gas to escape and it is used for fluids with suspended material
What is a segmental orifice plate?
An office please, with a semi circle hole Is used for fluid with a lot of suspended material once the material is not abrasive
What is a metering pump
Positive displacement pumps which provide a predictable and accurate rate of fluid flow
What is a meter
Devices used to measure indicates and record the value of a measured variable
Turbine flowmeter principle of operation
A suspend multi bladed rotor perpendicular to the flow in the pipe , the flow allows the rotor to rotate at a rate directly proportional to the volumetric flow
Advantages and disadvantages of a turbines
High accuracy and linear
Expensive and can’t withstand surges
