Welcome to the Blue-White guide to flow meters and their functions. Flow meters are devices used to measure the flow of fluids, such as fuel, water, and other liquids. They are essential for many industries and applications, including industrial process control, medical diagnostics, and energy management. This guide will provide an overview of the different types of flow meters available from Blue-White and information on how to use and maintain them properly.

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Flow Meter

A flow meter is a device used to measure the flow rate or quantity of a gas or liquid moving through a pipe. Flow meters measure the volumetric or mass flow rate of a liquid or gas. They are used to measure how much of a substance passes through a pipe over a period of time. Flow meters can measure flow in many applications, including water, oil, fuel, air, and steam.

They have applications in many industries, including water treatment, heating and air conditioning, industrial manufacturing, process control, and waste management.

For Starters, What is Flow?

Flow is a term used to describe the movement of materials or energy from one place to another in a continuous and organized manner. This can refer to the flow of fluids such as water, gas, and oil. Flow is an important concept in engineering and manufacturing in understanding how systems and processes work.

In this case, we will refer to flow as it applies to fluids in pipes. And in this application, flow is typically divided into two types: Open channel flow and closed conduit flow.

Open Channel Flow

Open channels are streams with an exposed surface and unrestricted access to the atmosphere. For example, canals and pipelines that are not completely full, such as drains and sewers.

In open channel flow, gravity is responsible for the motion of the liquid. The water level will gradually decrease down the stream as the flow progresses.

Closed Conduit Flow

Closed conduit flow is the flow of a liquid or gas through a pipe, channel, or another closed vessel. Closed conduit flow typically occurs at a constant velocity and depends on factors such as the pressure difference between the ends of the conduit and its length.

F-420 Acrylic Flow Meter

Water supply and district heating pipes are common places to observe closed conduit flow. Even drinking straws are a simple but efficient example of this. The flow rate here is largely determined by the pressure difference between the two ends, the distance between them, and the area of the conduit. Additionally, the hydraulics of the pipeline &#; such as its shape, roughness, and bends &#; also have an impact. All these factors come together to create the rate of flow.

Ranges of Flow Pressure

Flow pressure measures how much force is needed to move a liquid or gas through a system. It is measured in pounds per square inch (PSI) or kilopascals (KPa). The flow pressure range can vary greatly depending on the type of system, the size of the pipes, and the type of liquid or gas being pumped. For example, a residential water system typically operates at a much lower flow pressure than an industrial system. Flow pressure can also be increased or decreased by changing the size of the pipes, the number of fittings, and the type of pump.

Ranges of Temperature

Any flow will also have a temperature, with the typical range in most industries where they are used being from -40°F to +400°F (-40°C to +204°C). And to measure this, flow meters are designed to measure the flow rate in fluids with a wide range of viscosities, temperatures, and pressures. Flow meters can also detect changes in flow rates and can be used to detect leaks or other irregularities in the system.

Another term is thermal flow measurement, which reads how much heat is transferred while a gas passes a surface. The two main measurements taken with regard to temperature are simple readings via a temperature sensor and a heated flow sensor that measures the heat transfer from the flow of any given material inside the system.

F-460 Polysulfone Flow Meter

What Does a Flow Meter Do?

As mentioned above, a flow meter is an instrument used to measure the flow rate of liquid or gas. It measures the flow rate by detecting and monitoring changes in pressure, level, or another variable caused by fluid passage through pipes.

Types of Flow Meters and Their Functions

Flow meters measure fluids, but fluids can be any liquid, viscous, or gas known to us. Hence, a wide range of flow meters is available on the market. All of these types vary in function and application.

Differential Pressure Flow Meters

Differential pressure flow meters employ the Bernoulli Equation, which states that a fluid&#;s pressure decreases while its speed increases. These types of flow meters report the difference between the two measurements. The first measurement causes a shift in kinetic energy when the air is forced through a hole in the flow meter, which is then measured by the second element.

The sub-types of differential pressure flow meters are rotameters / variable area flow meters, orifice plates, venturi flow meters, and pitot tube flow meters. These meters measure the pressure difference between two points, allowing for a precise calculation of the fluid flow rate.

Rotameters / Variable Area

A variable area flow meter is a differential pressure flow meter. Variable area flow meters are simple, versatile, and cost-effective devices that operate at a relatively constant pressure drop and measure liquids, gases, and steam flow. The variable area flow meter is popular for industrial and commercial flow indication because it has a linear scale, a relatively long measurement range, and a low-pressure drop &#; plus, they are simple to install and maintain.

Orifice Flow Meter

The orifice plate flow meter is a differential pressure flow meter used in clean liquid, gas, and stream mass flow measurements. It is available for a wide range of pipe sizes and allows for measuring fluid flows in larger pipes (over 6&#; in diameter).

Venturi Flow Meter

Venturi flow meters allow the fluid to flow through a constricted section of pipe called a throat, where a pressure difference is created. The liquid speeds up and creates a pressure differential as it passes through, which is then used to calculate the volumetric flow rate of the fluid. Venturi meters are often used in applications requiring high precision levels with large volumes of liquid at low-pressure drops. They&#;re also suitable for liquids with a high solids content. Additionally, they are relatively easy to install because they have no moving parts. They can be fitted via flanged, welded, or threaded-end fittings, making them a popular choice for many applications.

Pitot Tube Flow Meter

Pitot tube flow meters are a common and cost-effective tool for measuring fluid flow rate in a pipe or duct. The pitot tube is inserted into the pipe to measure the difference in pressure between the upstream and downstream of the flowing fluid.

The installation process for a pitot tube is relatively straightforward, as it typically involves drilling a hole into a pipe and inserting the pitot tube into the fluid path with its impact port facing directly into the fluid flow.

Pitot tube flow meters remain attractive for many applications due to their low cost and easy installation process. They&#;re frequently used in HVAC and commercial aquatics systems, for example. Moreover, they offer minimal pressure drop, meaning they do not significantly impede the flow rate of the fluid.

F-300 Pitot Tube Acrylic Flow Meter

Positive Displacement Flow Meter

A Positive Displacement Flow Meter is a device that measures the flow rate of a fluid by measuring the amount of fluid that is displaced by a series of chambers or rotors. This type of flow meter is highly accurate, durable, and efficient and is commonly used in industries such as oil and gas, food and beverage, and chemical processing.

PD or Positive Displacement flowmeters utilize a rotating mechanism within a precision-engineered chamber to capture fluid pockets, like filling a beaker with liquid and pouring it down an aisle, counting each fill.

• Reciprocating Piston Meter:

A reciprocating piston meter is a positive displacement flow meter that measures the volumetric flow rate of liquids and gases. It consists of a chamber with a piston, an inlet and an outlet valve, and a pressure transducer. The piston is driven by an external power source, such as an electric motor, magnetic field, or pneumatic cylinder, and moves back and forth in the chamber. As the piston moves, it displaces a fixed volume of liquid or gas, and the flow rate is calculated based on the speed of the piston and the volume displaced. The inlet and outlet valves open and close to control the flow rate, and the pressure transducer measures the pressure inside the chamber.

• Oval-Gear Meter:

An oval-gear meter is a positive displacement flow meter that measures fluid or gas flow through two oval-shaped gears with close-fitting teeth. The gears are connected to each other and are placed in a chamber that has a known volume. As the fluid or gas passes through the chamber, the gears rotate, and the volume of the chamber is displaced. The displacement of the volume is measured, and the flow rate of the fluid or gas is calculated.

• Nutating-Disk Meter:

A nutating-disk flow meter works by passing fluid through a disk that is mounted on a shaft, which is connected to a motor. The disk is free to rotate around the shaft as the fluid passes through, causing the disk to rotate, or nutate, at a rate proportional to the flow rate. The rate of rotation and nutation is then measured and converted into a flow rate.

• Rotary-Vane Meter:

A rotary-vane flow meter uses a rotary vane, a type of impeller, to create a pressure differential across the meter, which is then used to calculate the flow rate. The inner part of the rotary vane meter consists of several vanes, each connected to a central shaft. As the fluid passes through the meter, the vanes rotate, causing a series of gears to turn. The gears are connected to a mechanical counter that records the total flow rate. The rotary vane meter is highly accurate and reliable, often used in the automotive industry to measure fuel and oil flow rates. The rotary vane meter is also used in medical applications, such as anesthetic delivery systems. The design of the rotary vane meter allows it to be used in a wide range of temperatures and pressure ranges.

SONIC-PRO® S6A Digital Ultrasonic Flow Meter

Volumetric Flow Meter

Volumetric flow meters measure the speed of the flow rather than the actual volumetric rate directly. The volumetric flow rate is calculated by multiplying the measured velocity by the cross-sectional area at which it&#;s installed, accurately representing how much material passes through in a given time period. Flow meter technology has become more advanced, with digital displays becoming more commonplace with improved accuracy due to better calibration technology and new sensing methods.

Ultrasonic Flow Meter

Ultrasonic flow meters measure flow rate by detecting fluctuations in ultrasonic oscillations. They come in two varieties: time difference and Doppler. Time difference type meters, also called time-of-travel meters or transit meters, measure the time taken for ultrasonic waves to travel from one point to another, while Doppler-type meters measure the frequency shift of soundwaves reflected from the moving particles in the medium. Both are used for accurate flow rate measurement.

Mass Flow Meter

Mass flow meters measure the mass of a material that passes through the system in a given period of time. They measure the mass per unit of time, typically expressed in kilograms per second (kg/s). Mass flow meters measure the speed and density of the material as it passes through the device. This data is then used to calculate the mass flow rate. Mass flow meters are typically used to measure the flow of liquids, gases, and solids in industrial processes, such as the chemical, food, and pharmaceutical industries. Coriolis flow meters are the most popular mass flow meters used in industries today.

Blue-White Flow Meters For Any System

Flow meters are an incredibly important and versatile tool for measuring the flow of liquids, gases, and solids in a variety of industries. There is an ideal meter for any application, from ultrasonic flow meters to variable area flow meters.

Blue-White has you covered when it comes to fluid control processes. We manufacture industrial-grade flow meters that are accurate and robust, so you can depend on them to keep your processes running smoothly, safely, and cost-effectively. From rotameters / variable area flow meters to paddlewheel flow meters to ultrasonic flow meters, all our products are Made in the USA and ready to ship! Get peace of mind by knowing your flow meters are reliable and of the highest quality. Trust Blue-White for all your flow meter needs.

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Five Flowmeter Types

Flowmeters are helpful devices used in a variety of industries to measure the flow rate of a fluid as it passes through a pipe. These fluids could be water, oil, natural gas, steam or anything else. While all flowmeters share a common function, they are a bit different in the way they operate.

We&#;re going to discuss some considerations for choosing the best flowmeter for your work, then look at five common types of flowmeters and their applications. Then, we&#;ll talk about what to do if your company experiences a problem with a flowmeter.

Considerations to Make When Choosing a Flowmeter

When you&#;re looking for a flowmeter, you need to consider some crucial factors to make the best choice for your company&#;s application. If there were one flowmeter that worked perfectly for every situation, there wouldn&#;t be countless other flowmeter types to choose from. The reality is that there are many types of flowmeters, and their uses vary. Each flowmeter offers various advantages and capabilities that make it a valuable option in certain instances.

1. Fluid Properties

To start, you want to consider the properties of the fluid you&#;ll be measuring. First, is the fluid a liquid, a gas or steam? How dense or viscous is it? Does it contain any contaminants, such as air bubbles or debris, that could affect the reading?

One critical aspect of the fluid to consider is its Reynolds number. This value tells you about how a fluid moves through a pipe. If the number is under 2,000, the flow is laminar, meaning it flows steadily. If the number is higher than 2,000, the fluid is more turbulent. As you look at flowmeters, pay attention to the Reynolds range they are designed to handle, so you can ensure they&#;re a good fit for your application.

You may need to ask yourself some different questions about your fluid&#;s properties, depending on which types of flowmeters you&#;re considering. For example, if you want to use an electromagnetic velocity flowmeter, you&#;ll need to determine whether your fluid is a conducting substance.

2. Accuracy

Once you know the variables of the fluid you plan to measure, you can begin to look for a flowmeter designed to deliver an accurate reading for your application.

In many cases, you&#;ll have multiple options to choose from, all of which can work with your situation. However, some may offer a higher degree of accuracy than others. Pay attention to the level of accuracy different flowmeters can deliver. Generally, one of the most accurate types of flowmeters you can find is a positive displacement flowmeter, but this may not always be the best choice, depending on what you are using it for.

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We typically see accuracy measured in terms of a percentage, such as ±1%. In this example, the reading on the flowmeter could be as much as 1% above or below the actual value. Therefore, the lower the percentage, the more accurate the flowmeter is.

3. Cost-Effectiveness

Cost is a practical concern that is always worth noting. You may find a flowmeter that would deliver highly accurate results, but is outside the confines of your budget. Try to balance finding the best possible option with affordability.

Remember, cost-effectiveness isn&#;t only about the price tag. You might find an exceptionally cheap option that seems like it will work. However, if it&#;s too inaccurate or stops working shortly after you install it, it will end up costing you more in the long run, since you&#;ll have to replace it.

Look for an option that offers quality and durability, even if that means spending more than you&#;d like to upfront. This strategy enables you to get the most out of your flowmeter over time.

Types of Flowmeters

There are many types of flowmeters. Each type goes about measuring the flow rate of a fluid in a different way. We&#;re going to look at five main types of flowmeters you can find on the market today, including differential pressure flowmeters, velocity flowmeters, positive displacement flowmeters, mass flowmeters and open-channel flowmeters.

1. Differential Pressure Flowmeters

One of the most common types of flowmeters is called a differential pressure (DP) flowmeter. This flowmeter type is based on scientific principles that govern the way fluids, both liquids and gases, flow through pipes.

To maintain a consistent flow rate, a fluid that moves from a wider pipe to a narrower one will have to move through with a greater velocity. When a fluid&#;s velocity increases, the pressure decreases. What does a change in pressure have to do with flow rate?

According to Bernoulli&#;s theorem, you can accurately calculate a fluid&#;s flow rate based on the square root of the differential pressure. In other words, if you can determine the differential pressure, you can determine the flow rate. There are different types of DP flowmeters, but all of them operate according to this principle.

In a differential pressure flowmeter, the fluid you are measuring enters a narrower section of pipe, sometimes by way of an orifice plate. As the name suggests, a differential pressure flowmeter measures the difference in pressure that occurs as a result of the flow-restricted area. Then, a DP flowmeter does the necessary math to display the fluid&#;s flow rate.

Differential flowmeters are common throughout many industries that need to measure the flow rate of fluids. These include the oil and gas, water treatment, pharmaceutical, food and beverage, mining, chemical manufacturing and HVAC industries, among others.

2. Velocity Flow

In the case of velocity flowmeters, the flowmeter working principle is that the flow rate of a fluid is equal to a cross-section of the pipe multiplied by the fluid&#;s velocity. By measuring the velocity of the fluid flowing through the pipe, then, a velocity flowmeter can determine the fluid&#;s flow rate. Several kinds of flowmeters fall into the category of velocity flow.

• Vortex: Vortex meters include an obstruction that disrupts the fluid&#;s flow and causes it to form vortexes. The number of vortexes formed indicates the fluid&#;s velocity.
• Electromagnetic: When other factors remain consistent, the voltage induced by a conducting substance moving across a magnetic field directly relates to the velocity of the fluid. An electromagnetic flowmeter measures the voltage to calculate the flow rate.
• Turbine: A turbine meter includes freely rotating propeller blades, positioned perpendicular to the direction the fluid is flowing in. By measuring the frequency of rotations, the turbine flowmeter can calculate the flow velocity.
• Paddlewheel: A paddlewheel flowmeter is similar to a turbine meter. In this case, as the paddlewheel turns due to the moving fluid, a sensor picks up on magnets in the paddle as it turns. These produce electrical pulses that indicate the flow rate.
• Ultrasonic: Ultrasonic flowmeters use transducers to send sound waves through a fluid. The returning sound wave can signal information about the fluid&#;s flow. This method only works on certain types of fluids.

There are other types of velocity flowmeters, as well. Each is best suited for a particular fluid, but they all manage to calculate velocity to determine flow rate.

3. Positive Displacement

Another common type of flowmeter is the positive displacement (PD) flowmeter. A PD flowmeter is the only type of flowmeter that determines the flow rate of a fluid by measuring the volume of fluid that comes through the meter, rather than measuring some other aspect of the fluid that relates to flow rate and calculating the flow rate based on that.

The meter contains rotating components that resemble mechanical cogs. The movement of the fluid through the meter causes these cogs to rotate. Unlike gears that fit tightly together, these rotating components trap small pockets of fluid in the space between them as they turn. The mechanism counts the rate of rotation of these components to keep track of how much fluid has passed through. This process works because the cogs&#; rotational velocity links directly to the fluid&#;s flow rate.

The exact way a PD flowmeter measures the rate at which the rotating components turn can vary. One way is for the components to include magnets that trigger sensors outside the fluid chamber.

Positive displacement meters have a reputation for being extremely accurate. This accuracy is partly because their design accounts for nearly all the fluid that passes through. The margin for inaccuracy relates only to the tiny amount of fluid that manages to bypass the seal of the rotating components, sometimes called &#;slippage.&#;

In addition to being impressively accurate, PD flowmeters can handle a wide range of fluids when it comes to viscosity. A PD flowmeter may even be able to give a more accurate read for more viscous fluids, since they lend themselves less to slippage.

4. Mass Flow

A mass flowmeter, as the name suggests, measures the mass flow of fluid as it moves through a pipe. Mass flowmeters are common in the pharmaceutical, mining, wastewater, power and chemical and gas industries. These flowmeters are an ideal choice when you want to measure mass or when you&#;re working with a very viscous substance.

One popular means of measuring mass flow is by heating a section of fluid and noting the resulting change in temperature. A similar method is to keep a probe at a constant temperature and take note of how much energy the probe requires to do this.

Mass flowmeters that use heat to measure mass flow are called thermal dispersion flowmeters. Another common type of mass flowmeter is a Coriolis mass meter. Regardless of which method your meter uses to measure mass flow rate, you should note there is a difference in mass flow rate and volumetric flow rate.

Whereas a positive displacement flowmeter measures the volume of fluid that passes through, a mass flowmeter measures the mass of the fluid that travels through. A measure of volume would look something like cubic meters per second or another measurement of volume in a given amount of time. Mass is distinct from volume. You may see it measured by kilograms per second or a similar unit of measurement.

So, how can a measure of mass flow rate tell us the volumetric flow rate of a fluid? It turns out these measurements are related. By dividing the mass flow rate by the density of the fluid, a mass flowmeter can determine the flow rate in terms of volume. This process sounds fairly straightforward, but it can involve some extra steps to determine the actual density of the fluid, since it may vary depending on conditions.

5. Open Channel

Finally, there&#;s an open-channel flowmeter. This type of flowmeter includes a dam-like structure known as a primary device. Typically, the primary device is either a weir or a fume. We&#;ll look at the difference between these two types of devices in a moment.

If you know the relationship between depth and flow in your pipes, then by placing an obstruction in the pipe, the meter can take note of the difference in depth and use this information to calculate flow rate. The main difference between weirs and flumes is their shape.

Weirs are openings at the top of a dam, which can either be rectangular or V-shaped. As the water or other fluid flows over the dam, through the weir, the height of the fluid will increase. A greater increase in depth indicates a higher flow rate.

Flumes are similar to weirs, but they provide a constriction in width rather than height. As the fluid enters the narrower section of the channel, the water level changes which correlates to the flow rate.

In addition to playing a role in industrial applications such as wastewater treatment, open-channel flowmeters are a useful means of measuring the flow rate in free-flowing bodies of water such as streams and water.

How to Tell Your Flowmeter Has a Problem

 

Any flowmeter can experience problems, so you want to remain attuned to the readings your company&#;s flowmeter is providing and determine whether it&#;s operating consistently or may be having issues that are interfering with its ability to measure flow accurately.

If your flowmeter doesn&#;t seem to be working accurately from the outset, it&#;s likely due to improper installation. It could be that you need to reposition it to a section of piping that will deliver a more accurate reading. Or maybe the flowmeter&#;s calibration has been off since day one.

If your flowmeter has started to operate more erratically over time, you could have a maintenance issue. Sensors, flow lines and other components generally require some upkeep to continue to operate effectively over time. Be sure to pay attention to what sorts of maintenance tasks your company&#;s flowmeter calls for by carefully reading the manufacturer&#;s manual.

Each type of flowmeter is susceptible to various potential problems. For instance, electromagnetic flowmeters can experience issues if they get exposed to electrical detractors that interfere with the current. If you ever notice an indication that your flowmeter may not be operating accurately, have a service professional inspect it to diagnose the problem and offer solutions.

Flowmeter Maintenance From Global Electronic Services

There are many types of flowmeters, each of which offers various advantages and potential issues. The right flowmeter can help your company keep track of the flow rate of water, chemicals or any fluid that moves through your plant&#;s pipes. To ensure your flowmeter continues to deliver on its valuable purpose, be sure to address potential issues as soon as they arise.

Global Electronic Services can quickly provide you with a certified technician who has the expertise to repair your faulty flowmeter so you can maintain your operations. Learn more about our flowmeter repair services and contact us today.

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