FLOW MEASUREMENT & MEASUREMENT
OF LIQUID LEVEL
FLOW MEASUREMENT
Elements needs to consider during FLOW
MEASUREMENT
A technique used in any process requiring the transport of a
material from one point to another.
4) laminar or turbulent
5) pressure
3) hazardous/corrosive or safe
2) wet or dry
1) Clean or dirty
6) temperature
measuring devices categories
Secondary devices (rate meter)
Primary devices (quantity meter)
Measure the amount of fluid in terms of mass or volume
Advantages: Simple, economic and extremely
accurate.
commonly used device
Nutating Disc Meter
Sliding Vane Type Meter
Lobed Impeller Flow Meter
application: domestic water system.
application: dispensing petrol/diesel in the
fuel filling station.
application: metering of gas and
redefined petroleum products
is vane type of positive displacement flow meter, creating high accuracy management and low pressure loss by decreasing rotation resistance
due to small revolution resistance, it gives large volume management with low pressure loss
A type of positive displacement meter in which a fluid stream is separated into discrete quantities by rotating, meshing impellers driven by interlocking gears
desccription of process
1) water flows directly into meter housing
2) water flows through the meters internal
strainer before it enters measuring chamber
3) strainer do protects measuring chamber
due to debris in the water
4) movable disc that is located on sliding ball guided by a thrust roller as the water flows in the measuring chamber
5) there are space formed between disc and
chamber wall that has a constant volume
6) Smooth motion of disc eliminates the annoying noise that produced by some other types of positive displacement
7) flow rate
Variable head meter
pitot tube
advantages
know as the air-speed indicator used in
aircrafts.
No pressure loss in the flow system.
Easily inserted to a small hole.
Simple and low cost.
useful in checking the mean velocities.
Bernoulli Equation
P1 + (ρv1)^2 /2 + ρgh1 = P2 + (ρv2)^2 /2 + ρgh2
Re = (ρ u2) / (μ u / L)
If Re < 2000 = laminar flow.
If Re > 4000 = turbulent flow.
If 2000<= Re <= 4000 = Critical zone between
laminar & turbulent.
static pressure + dynamic pressure = total pressure
(Ps + ρ x (V^2)/2 ) = P1