Flow measurement quantifies the movement of water and can be done by determining displacement or velocity. Accurate flow measurement is important for industries like power plants for safety and revenue as well as for homeowners to be charged correctly. Flow is controlled using valves and measured using various types of flow meters like positive displacement, mass, and velocity meters. Selection of the proper flow meter and control valve depends on the application and engineering requirements.

1. FLOW CONTROL AND
MEASUREMENT
(FLOW VALVES AND METERS)

2. WHAT IS FLOW
MEASUREMENT?
Flow measurement can be defined as quantification
of the movement of water in a given channel.
Flow can be measured either by determining the
displacement and/or Velocity of the water. Water
meters usually control measure and display total
usage in cubic meters, on either mechanical or
electronic registers.

3. WHAT IS THE NEED OF FLOW MEASUREMENT?
• Flow measurement is integrated into every aspect of modern life,
from the measurement of water flow in power plants to the
metering of household water.
• Specifically, the power plant must measure correctly for safety,
efficiency, and revenue, while the homeowner is interested in being
charged correctly.
• Accurate flow measurement has a positive impact on energy
conservation.
• It helps understand storm water volume and how much flow is
passing through the treatment plant — and this, in turn, protects the
environment and helps determine water quality standards.
Water treatment plant
operator

4. Flow can be divided into two main flows which are:
• Open channel flow and
• Closed conduit flow.
VALVES AND WATER METERS
Flow is controlled by use of valves at intervals to
either to slow down, allow faster flow or completely
shut down the flow.
Some water meters usually perform both the
function or making readings and controlling flow
while others just conduct measuring only.
Water Meter
Well, How much water do you use?

5. Garden Hose Water Meter Tracks The Amount Of Water You Use

6. DIFFERENT TYPES OF FLOW MEASUREMENT
Controlling flow of a fluid-power system does not necessarily mean regulating volume per
unit of time from a valve. Flow rate can be specified three different ways, so it is important
to be aware of how flow is to be specified or measured:
• Volumetric flow rate, Qv, expressed in units of in.3/sec or min - or cc/sec or cc/min in SI
metric measure - is used to calculate the linear speeds of piston rods or rotational speeds
of motor shafts.
• Weight flow rate, Qw, expressed in units of lb/sec or lb/min, is used to calculate power
using English units of measure.
• Mass flow rate, Qg, expressed in units of slugs/sec or slugs/min for English measure - or
kg/sec or kg/min in SI metric measure - is used to calculate inertia forces during periods
of acceleration and deceleration.

7. FLOW METERS
• A flow meter is a device used to measure the flow
rate or quantity of a gas or liquid moving through
a pipe. Flow measurement applications are very
diverse and each situation has its own constraints
and engineering requirements.
A Turbine Meter
1.Positive
Displacement/Volumetric -
Directly measure the actual
volume
Eg. -Piston flow meters, Gear
flow meter, Rotary Vane Meter
2.Mass -The output signal is
directly related to the mass
passing through the meter.
Eg. – Thermal And Coriolis Flow
Meter
3.Velocity - The output signal
directly related to the velocity
passing through the meter.
Eg. – Electromagnetic,
ultrasonic flow meters etc
VARIOUS TYPES OF FLOWMETERS:

8. FLOW METERS IN USE
The common types of flowmeters that find
industrial applications can be listed as below:
• (a) Obstruction type (differential pressure or
variable area) (b) Inferential (turbine type), (c)
Electromagnetic, (d) Positive displacement (e)
fluid dynamic (vortex shedding), (f) ultrasonic
and (g) Mass flowmeter (Coriolis). VIDEO: The Differential Pressure Flow Measuring
Principle (Orifice-Nozzle-Venturi)
VIDEO: The Ultrasonic Flow Measuring VIDEO: The Electromagnetic Flow Measuring

9. CONTROL OF FLOW RATE WITH VALVES
• Flow-control valves include simple orifices to
sophisticated closed-loop electrohydraulic
valves that automatically adjust to variations in
pressure and temperature.
• The purpose of flow control in a hydraulic
system is to regulate speed and thus
controlling flow rate. The main functions of
Control Valves are as follows:
 control the flow capacity
 control the water level
 control the pressure in case of a following
pipeline.
Definition, VALVE: A valve is a mechanical device that blocks a pipe either partially or completely to
change the amount of fluid that passes through it.

10. TYPES OF VALVES
The many different types of valves
all have different names. The most
common ones are the butterfly,
cock or plug, gate, globe, needle,
poppet, and spool.

11. SUMMARY
• The measurement of flow should be simple, as it
is a fundamental part of our industry(water).
• The need to automatically control with flow
meters and/or measure more accurately brought
about a refinement of measurement techniques
that has provided greater efficiency.
• All of the technologies available are valid, and all
of them have their strengths and their
weaknesses. It’s up to the engineer to select the
most appropriate technology and to ensure that
it is designed and installed correctly.

12. END
Information Courtesy:
http://www.wateronline.com
http://www.explainthatstuff.com/valves.html
http://hydraulicspneumatics.com/
http://www.youtube.com , Channel- Endress+Hauser