The flowmeter is a kind of meter used to measure the flow of fluid in a closed pipe or open channel. How to choose the right
flow meter for different applications and media and working conditions? To help you solve the problem of how to select the flow meter, Silver Automation Instruments has collect some information for your reference.
How to select a flowmeter which can work for your application also with cheap price? According to the measurement principle, there are differential pressure flow meters, rotor flow meters, positive displacement flow meters, turbine flow meters, electromagnetic flow meters, vortex flow meters, ultrasonic flow meters, thermal gas flow meters, etc.Different types of flowmeter selection methods and reference factors are also different, and should be selected according to their specific functions and performance. Below I will introduce the commonly used flowmeters:
Magnetic Flowmeter
Electromagnetic flowmeter is an instrument
for measuring conductive liquid made according to Faraday's law of
electromagnetic induction. When the conductive fluid moves in the direction of
the magnetic field line in a magnetic field, it will induce an induced
electromotive force whose direction is perpendicular to the direction of the
magnetic field and the direction of the fluid flow, and its value is
proportional to the magnetic induction intensity and the fluid movement speed.
The electromagnetic flowmeter is composed of two parts, the sensor and the
converter, and it can also be made into an integral type or remote transmitter.
Magnetic flowmeter has many excellent features, can measure dirty flow and
corrosive flow;
Mag flowmeter can measure sea water,
sewage, sulfuric acid, nitric acid, sodium hydroxide, corrosive liquid,
hydrofluoric acid, potassium nitrate, mud, milk, pulp, water, fire fighting
water;It can measure various corrosive liquids such as acid, alkali and salt, and can be used as an acid flowmeter and an alkali flowmeter.
Mag flow meter sensors normally used: 1/2
inch Magmeter, 1”, 2”, 3 inch, 4 inch, 6 inch mag flow meters, 8 and 10 inches
magnetic flow meters.
Magnetic flowmeter has an electronic
display that can display the instantaneous flow and cumulative amount of the
liquid, and also it is bi-directional flowmeter;
It can be made into an industrial inline
type flow meter or insertion type magnetic flow meter;
Mag mete cannot be used to measure gases, vapors, and liquids containing large amounts of gas.
Magnetic flowmeter cannot be used to measure liquid medium with very low conductivity and cannot measure high temperature and high pressure fluids.
Positive displacement flow meter
Positive displacement flow meters are also
called PD flow meters. The fluid is continuously divided into single known
volume parts by mechanical measuring elements, and the total fluid volume is
measured according to the number of times that the measuring chamber is filled
and discharged with this volume part of fluid successively. Positive
displacement flow meters are classified according to their measuring
components, which can be divided into oval gear flow meters, roots flow meters,
helical gear flow meters,Bi rotor flowmeter, membrane gas meters (domestic fuel
meters), etc. Positive displacement flow meter can be used to measure diesel,
gasoline, heavy oil, biodiesel, asphalt, methanol, kerosene, lubricating oil,
grease .,etc. The material can be 1/2”,1”,2”, 3”,4”,6”,8” and 10 inch PD flow
meters.
Now we have developed micro PD flow meters
for low flow liquid measurement, the flow meter size can 2mm, 4mm, can detect
low flow starts from 0.6 L/h. It can be made into Teflon material for corrosive
and aggressive liquid flow rate measurement.
Coriolis mass flowmeter
Coriolis mass flowmeter is a direct mass
flowmeter that uses the principle of Coriolis force proportional to the mass
flow rate when the fluid is in a rotating system while moving in a straight
line.
Coriolis flowmeter is widely used in
petrochemical and other fields. It is one of the most advanced flow measuring
instruments in the world. .It can be used to measure liquid, gas, steam, etc.
It can measure medium with extremely high viscosity, for example, as a resin
flowmeter. , syrup flow meter, asphalt, heavy oil ,glue,etc.
The min size for Coriolis flow meter we
can produce is 3mm which can detect mass flow 0-40 kg/h, normal request
Coriolis flow meter : 1 inch Coriolis flow meter, 2inch, 3 inch, 4 inch, 6 inch
, 8 inch, 10 inch and 12inch Coirolis flow meter.
Vortex flowmeter
Vortex flowmeter is to place a
non-streamline vortex generator (bluff fluid) in the fluid, and the fluid
alternately separates and releases two series of regularly staggered vortices
on both sides of the generator. Within a certain Reynolds number range, the
separation frequency of the vortex is proportional to the average flow velocity
in the pipeline, and various types of detectors can be used to detect the
vortex frequency.
Vortex shedding flow meter is mainly used
for flow measurement of industrial pipe medium fluid, such as gas, liquid,
steam and other medium. It is characterized by small pressure loss, large
measuring range and high precision. It is almost unaffected by parameters such
as fluid density, pressure, temperature and viscosity when measuring the volume
flow rate. We often use vortex flow meter to measure steam (with external
pressure and temperature compensation), ,measure low-conductive liquids and
clean gas.
Turbine flowmeter
Turbine flow meter is a kind of velocity
flow meters. They use a multi-blade rotor (turbine) to sense the average flow
rate of the fluid to deduce the flow rate or total volume. The rotational
movement of the rotor can be detected by mechanical, magnetic induction,
optical or electronic means and displayed or recorded by a reading device.
Generally, it is composed of two parts, a sensor and a display, and it can also
be made into an integral type. Turbine flowmeters can be made into 0.5%
accuracy.
Flow meter size can be
6mm,10mm,1/2”,3/4”,1”,1.5”,2”,3”,4”,5”,6”,8”,10”.
Turbine flow meters are widely used in the
following measurement objects: petroleum, diesel, portable water, deionized
water, drinking water, acetic acid, organic liquids, inorganic liquids,
liquefied gases, natural gas, gas and cryogenic fluids.
Digital turbine flow meters can be powered
by 24V DC or 220V AC, it can have 4-20mA, pulse or frequency outputs; It can
also have MODBUS, RS485 or HART protocol.
Thermal (gas) mass flowmeter
Thermal mass flowmeter is a digital gas
flow meter that uses the relationship between fluid flow and heat source to
transfer heat to the fluid to measure gas flow. At present, there are two types
commonly used: one type is a thermally distributed (also known as calorimetric)
flowmeter, which is mainly used for small and micro gas flow measurement or
used as lab gas flow meter. If it is used as a component flow type, it can also
be used in large and medium flow; the other type It is a thermal dispersion
type (also known as King's law) flowmeter, made as an insert type gas flow
meters, used for large size flow measurement or circular piping or rectangular
ducts. Thermal flow meters directly detect mass flow meters, which are mainly
used for gas flow measurement, flue gases, LPG , Flare gas ,Propane ,Compressed
air,Biogas, N2,O2.,etc;
Rotameter
Rotameter is a kind of variable area
flowmeter. In a vertical tapered tube that expands from bottom to top, the
gravity of the float with a circular cross-section is borne by the hydrodynamic
force, so that the float can rise and fall freely in the tapered tube. The
position of the float indicates the amount of flow. Rotameters are divided into
two categories according to the material of the cone tube: glass tube and metal
tube rotameters. According to the remote transmission type, it is divided into:
electric remote transmission with 4-20mA output and local reading type without
any power supply. Float flow meters are especially for small and micro flow
measurement.
It can be used to measure the flow of
liquids, gases, and vapors, rotameters sizes are 1/2”,1”,2”,3 inch rotameters,
4 inch, 6 inch and 8” rotameters.
Ultrasonic flowmeter
The ultrasonic flowmeter is a flow meter
that measures the flow rate by detecting the effect of fluid flow on the
ultrasonic beam (or ultrasonic pulse). According to the principle of signal
detection, ultrasonic flowmeters can be divided into transit time ultrasonic
flow meter, Doppler ultrasonic flow meter, beam shift method, = noise method,
etc. There are no obstructions in the flow channel of the instrument, it can
also be non-invasive flow meter. They are a type of flowmeter suitable for
solving difficult problems in flow measurement, especially in large-diameter
flow measurement. It is one of the flowmeters that have developed rapidly in
recent years. Transit time ultrasonic flow meter can be used to measure clean
water or diesel.
Differential pressure flow meter
Differential pressure flowmeter is a flow
metering instrument that calculates the flow rate based on the differential
pressure generated by the flow detection primary flow element, the known fluid
conditions, and the geometric dimensions of the primary element and the
pipeline.
Differential pressure flowmeter is
composed of a primary element (detection part) and a secondary device
(differential pressure transmitter and flow display instrument). Differential
pressure flowmeters are usually classified by the type of detection parts, such
as orifice flowmeters, venturi flowmeters, and V-cone flowmeters.,etc. The
detection parts of the differential pressure flowmeter can be divided into
several categories according to its principle of action: throttling type,
hydraulic resistance type, centrifugal type, dynamic pressure head type,
dynamic pressure gain type and jet flow type. Generally, the throttling type
differential pressure flowmeter is the mostly used.
The selection of flowmeters is impossible to be quite perfect, because each flowmeter has its own unique advantages and disadvantages. It can only be selected according to different measurement methods and structures, requiring different measurement operations, methods of use and conditions of use to select safe and economical safety, the best type of durability.
Information Needed To Select a Flow Meter
1. The name and characteristics of the fluid (corrosive, viscous, abrasive, etc.)
2. Working flow (normal flow, maximum flow, minimum flow)
3,Working pressure (maximum, minimum working pressure), if there is negative pressure formation, please specify to China Flowmeter factory.
4, working temperature
5, the conductivity of the fluid, electromagnetic flowmeter can only measure the medium with conductivity ≥ 5μS / cm.
6, Collect the installation location and installation method, such as flange connection, or wafer connection, or threaded connection, or sanitary tri-clover connection flow instruments.
7. Power supply mode, such as battery power supply, or 220V AC power supply, or 24V DC public power supply.
8, process pipe size
9, Please provide communication methods, such as the need to output 4-20mA, or pulse output, or RS485 and so on.
