Please enable JavaScript.
Coggle requires JavaScript to display documents.
FLOW MEASUREMENT - Coggle Diagram
FLOW MEASUREMENT
PRIMARY DEVICES
(QUANTITY METER)
Nutating Disc Meter
Nutating disc meters are the most common and accurate type of positive displacement meters
A disc attached to a sphere is mounted inside a spherical chamber
As fluid flows through the chamber, the disc and sphere unit nutates. The nutation causes a pin, mounted on the sphere perpendicular to the disc, to rock.
These flow meters may use a Hall sensor to sense the rotation and the same was converted into equivalent flow.
Sliding-Vane-Type Meter
High accuracy measurement and low pressure loss by decreasing rotation resistance
stable measurement with high accuracy
Easy to read big indicator
Application : dispensing petrol/ diesel in the fuel
filling station.
Lobed-impeller Meter
Application :
refined petroleum products
metering of gas
Two rotating impellers, designed with a figure eight cross section, rotate in opposite directions due to the forces exerted by the gas flow being measured.
does not require external power supply
A technique used in any process requiring the transport of a
material from one point to another
Knowledge of the direction and velocity of flow.
Reynolds
Number
the non-dimensional velocity
defined as the ratio of
the viscous or friction force
μ
the inertia force
ρ u L
interpreted as the ratio of
the shearing stress
μ u / L
the dynamic pressure
ρ u^2
Bernoulli’s equation
a statement of the conservation of
energy principle
pressure to be energy density.
TYPES OF FLOW
LAMINAR FLOW
Re < 2000
TURBULENT FLOW
Re > 2000
2000<= Re <= 4000
Critical zone between
laminar & turbulent
Application
Essential in many application such transportation of slurries material (cement), compressed natural gas in pipelines, water and gas supply systems to domestic consumers
Secondary devices
(rate meter)
Variable head meter - Pitot tube
known as air-speed indicator
its a slender tub that has two holes on it. The front hole is placed in the airstream to measure the stagnation pressure. The other side hole measure the static pressure
simple and low cost
easily inserted to a small hole
