The
effectiveness of liquid flow processes and flow systems depend largely on the
type of water flow switch or flow sensor used. These are essential instruments
that offer accurate flow measurements of various kinds of fluids and gases.
However, the type of flow meter or sensor determines the effectiveness of flow
accuracy in any application. Among the many types of water flow meters is the
paddlewheel flow meter. This type of liquid flow meter offers effective
readings when measuring the flow rate of different fluids.
This post focuses on paddlewheel flow meter and
their effectiveness when it comes to different fluid flow measurements. Read along
for a better understanding of how this type of flow meter operates.
Paddlewheel Water Flow Switch
A
paddlewheel flow meter belongs to a category of flow meters called velocity
flow meters. This category of flow meters measures flows rate by providing
readings in volumetric flow rate. The velocity of the fluid is directly
proportional to the volume flow rate. When measuring flow rate, the sensitivity
of the paddlewheel flow meter will drop if the Reynold number goes beyond
10000. Examples are electromagnetic, vortex shedding, ultrasonic, vortex
shedding, and paddlewheel flow meters.
Understanding
how different types of flow meters operate is essential for the proper
utilization of these flow measuring devices. It is also essentially relevant
for the proper installation of such devices. Paddlewheel flowmeters are
distinguished by the type of materials used to design them. They can either be
made from stainless steel or plastic. Paddlewheel flow meters can also be
distinguished by detecting or evaluating signals, which can either be through
an HT coil sensor, hall sensor, coil sensor, or optical sensor.
Since
there are various kinds of paddlewheel flow meters, here are a few examples and
how they operate:
Paddlewheel Water Flow Switch Types and Applications
Inductive Detection and Pulse Output
This
type of paddlewheel flow sensor is made from plastic, and it is also called a
PVDF or a PP paddlewheel. It comes fitted with rotating magnets, molded
permanently along the arms. With precision, the magnets spin on two ceramic
bearings and a resistant ceramic spindle. Magnetic fields from the spinning
paddle wheel are detected outside the fluid flow area. From each revolution,
two output signals are generated. Frequency changes are determined
proportionally by the speed of the rotation. An integral electronics board is
used to convert the signal into a square-wave frequency signal.
Inductive Detection and Sinusoidal Output
These
flow meters are also made from plastic and are also called PP or PVDF
paddlewheel flow meters. In each arm, there are four spinning magnets, molded
permanently. It also comes with a ceramic spindle and two ceramic bearings that
are wear and tear-resistant. The function of these two components is to help
the paddle wheel spin with precision. In addition, a ferrite core coil is put
outside the fluid’s flow area to detect the magnetic field from the rotating
paddle wheel.
The
frequency changes based on the revolutions generated, which are proportional to
the rotational speed. The rotation of the paddle generates a sinusoidal voltage
signal. The coil’s voltage signal is directly proportional to the measured
volumetric flow rate. Since this type of paddlewheel flow meter is two wired,
extra auxiliary power is unnecessary. To allow voltage dependency, a
battery-operated display unit is connected.
Optical Detection and Pulse Output
Made
from PVDF material, the optical detection and pulse output water flow switch
consist of two ceramic-made bearings and a spindle to make them resist wear and
tear. Two infrared receivers and transmitters in an electronic housing outside
the fluid flow area. Plastic material is used to separate them since it allows
infrared radiation to pass through. The infrared radiation diodes detect
paddlewheel rotation. Integrated electronics are used to convert reflected
I-Signal into a square wave frequency signal. Volumetric flow rate reading is
directly proportional to the square wave frequency signal.
The
ferromagnetic particles found in the flowing fluid in this optical type of
liquid flow meter are used to detect the flow rate. The fluid flow direction is
also detected by these particles found in flowing media.
Stainless Steel Inductive Detection and Pulse Output
Made
from stainless steel, these types of paddlewheel flow meters have very low
ferromagnetic characteristics. The spindle in this type of paddlewheel flow
meter is made from high-tech ceramic or stainless steel. The bearing is made
from PEEK or ceramic. Inside the top-mounted electronics is an HT coil with permanent
molded magnets. Electronics are also found in the HT coil that converts a coil
signal into a square wave frequency signal.
Conclusion
Paddlewheel
flowmeters are the best kinds of velocity flow meters that make ideal
instruments for measuring clean fluids such as water. However, using these
water flow switch types to regulate any
other fluid besides clean water may lead to inaccuracies. Since paddlewheel
flow sensors have moving parts, using dirty fluids that have particles or
debris may damage them and cause flow measurement errors. Corrosive fluids may
also damage the moving parts.
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