Mechanical vs. Digital Flow Meter — What's the Difference?

When attempting to determine which flow meter(bn,zu,pt) is a more practical option for your desired use, it's best to know as much about them as possible. The function of a flow meter is easy enough to understand, but when all of the different types of flow meters you can find on the market work in different ways for their various designed uses, how do you know what to choose? Read on to learn more about mechanical and digital flow meter types so you can make an informed decision.

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What Is a Flow Meter?

You can define a flow meter as an instrument specially designed to measure the flow of gases, fluids and semi-fluids (slurry) in piping systems.

The complexities of flow meters stem from the vast range of options one has to choose from, depending on various circumstances. There is no universal flow meter that will be suitable for every type of application. When used in certain circumstances, each type of flow meter has its advantages and disadvantages. While there are too many types of flow meters to cover each in this article accurately, some well-known flow meter types include:

• Turbine Flow Meters
• Differential Pressure Flow Meters
• Positive Displacement Flow Meters
• Magmeters (Magnetic Flow Meters)
• Mass Flow Meters

Within the vast range of flow meters, there are two primary types which every flow meter branches off from – mechanical and digital flow meters. When deciding whether or not you need a digital or mechanical flow meter, you need to decide whether power is required or not. But that's not the only difference between these two types of flow meters. We'll discuss some of the primary differences between mechanical and digital flow meters so you can decide which is better suited for your specific application.

What is a Mechanical Flow Meter?

A mechanical flow meter will have mechanical moving parts such as gears, rotors, impellers, or turbines to measure total flow. Mechanical flow meters will only indicate total flow, not instantaneous flow rate since there is no computer available to convert total flow over time into instantaneous flow rate. Mechanical flow meters require no power. The function of a mechanical flow meter is mainly dependent on a constant flow to keep the impeller moving. Mechanical flow meters have been widely used since the 20th century and are still a popular option today. Some of the featured mechanical flow meters widely used today include:

• Positive Displacement Flow Meters: A positive displacement flow meter works by utilizing mechanical elements to divide liquids into a single known volume. It then repeatedly fills and discharges the volume to accumulate the total amount of liquid. These work best when measuring the volume flow of high viscosity and varying viscosity fluids.
• Turbine Flow Meters: Within a turbine flow meter, the liquid or gas flows through a sensor housing. The impeller blades are located parallel to the angle of the flow direction to rotate the blades and measure the flow. Turbine flow meters can have impellers with magnets embedded in the blades. When the magnet passes a pickup coil located outside the fluid chamber, the computer counts the pulses and converts them to total flow and flow rate.
• Rotameter Flow Meters: Rotameter flow meters are variable area flow meters based on float position measurement. The differential pressure of the upper and lower ends form a force for the float to rise until it stabilizes at a certain height. These mechanical flow meters are used for liquid and gas volumetric flow measurement and control.

When Should You Use a Mechanical Flow Meter?

Mechanical flow meters are excellent for hazardous locations and applications where no power is available or desired, and where batteries are not acceptable due to replacement concerns. Mechanical flow meters are perfect for the easy monitoring of liquid flow rates such as water, fuel and viscous liquid.

If you're looking for a flow meter that measures total flow and rate of flow with high accuracy, you may want to think about investing in a digital flow meter.

What is a Digital Flow Meter?

A digital flow meter is a meter that includes a digital computer display to provide you with your measurements of total flow and instantaneous flow rate. A digital flow meter can take the data captured and display it in easily readable quantities that make it more reliable than its traditional mechanical water flow counterparts. In addition to using an impeller to determine flow, a digital flow meter can calculate flow with an electrode sensor that measures induced voltage to measure velocity and flow rate. The significant advantage of digital flow meters is that they require minimal maintenance requirements and have an increased lifespan because there are no moving parts that can jam or break.

Unlike mechanical flow meters, you can find almost every type of flow meter outfitted with a digital display.

When Should You Use a Digital Flow Meter?

If the flow rate is required, a digital flow meter is the right choice. Digital flow meters use external power or batteries, making them more accessible and easier to use on a day-to-day basis. If applications have particulates in the fluid, a digital flow meter such as a Magmeter, which has no moving parts, is a good fit. Positive Displacement Flow meters can also be digital flow meters.

The downside many people face when looking to purchase a digital flow meter is the price. These flow meters are often more expensive because of the highly specialized technology within them. It's often noted that digital flow meters may turn out to be more profitable to use because of the use of the instantaneous flow rate measurement available.

Shop GPImeters for Mechanical & Digital Flow Meters

GPImeters specializes in both mechanical and digital flow meters. We carry a diverse inventory to meet your desired application, as well as flow meter modules, replacement parts, accessories and more. No matter what flow meter type you require, the experienced team at GPImeters will ensure you find the best flow meter for you – you can request a quote at any time. If you have any questions about the types of flow meters we offer, feel free to contact us. The flow meter experts are always standing by to help.

Article | May 25, .
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From agriculture, to manufacturing, to the oil and gas sector, and beyond, flow meters play a vital role in ensuring safe, reliable operations of critical liquid and gas infrastructure. You must be able to measure what’s flowing where on a continuous basis. That’s why flow meters are an essential tool across a variety of industries today.

By delivering accurate, continuous visibility into flow rates - flow meters ensure that agencies and businesses have the information they need to maintain smooth operations and meet regulatory requirements.

What is a Flow Meter?

A flow meter is a device that measures how much liquid or gas moves through a pipeline in a given period of time.

By measuring flow rates, flow meters provide crucial visibility into what’s flowing where, within pipes, drainage systems, and other types of infrastructure. In turn, they help operators determine whether systems are properly balanced, ensure that each endpoint receives adequate supply, identify excessive flow rates that could damage pipes, and so on.

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What is a Water Flow Meter?

A water flow meter is a flow meter designed to measure the flow of water specifically, as opposed to other types of liquids (like oil or gasoline) or gases.

Water flow meters can be used to track the flow of water within a variety of applications. They can:

• Measure usageby individual households or communities within municipal drinking water systems.
• Track sewage flowto help municipalities ensure that their wastewater systems adequately meet demand.
• Help factory operatorsassess the amount of water being used to cool an industrial plant.

5 Types of Flow Meters and How They Work

All flow meters perform the same basic job: They measure flow by tracking how much liquid or gas moves through a fixture in a given period of time. However, several different types of flow meters exist, each of which uses a different approach for tracking flow.

Electromagnetic Flow Meters

Electromagnetic flow meters, sometimes called magnetic meters or mag meters, use electrodes to measure water flow. The electrodes, which are embedded on opposite sides of the surface through which liquid flows, create a magnetic field. By sensing the voltage generated by water as it passes through the magnetic field, electromagnetic flow meters can track flow rates with a high degree of accuracy.

Electromagnetic flow meters are generally low maintenance, because they have no mechanical parts that can break down. In addition, because there are no components directly in the path of the water, electromagnetic meters don’t impede water as it passes through. That means there is no degradation in flow during the measurement process.

Differential Pressure Flow Meters

A differential pressure flow meter forces water through a constriction of some type, such as an orifice or nozzle, and measures the water pressure on both sides of the constriction. A high pressure drop indicates high water flow.

The obvious downside of this type of flow meter is that it reduces pressure and can slow down water flow, causing permanent pressure loss. These kinds of flow meters are undesirable in applications that require maximum pressure throughout the system.

Mechanical (Turbine) or Propeller Flow Meters

Mechanical flow meters force liquid through a physical component that moves when the water pushes on it. The most common type of mechanical flow meter uses a propeller for this purpose. By measuring how fast the propeller or other mechanical component turns, this type of flow meter can record flow rates with a high degree of accuracy.

Because this type of meter contains mechanical parts that can wear down over time, however, mechanical flow meters require a relatively high degree of maintenance. Operators have to replace bearings and ensure that the propeller remains properly aligned in order to achieve accurate readings.

Ultrasonic Flow Meters

An ultrasonic flow meter uses ultrasonic waves to measure how fast liquid is traveling. By injecting waves into the liquid and listening for a response, this type of meter can assess flow rates almost instantaneously.

Because ultrasonic meters have few mechanical parts, they are a low-maintenance flow meter solution. However, because sound travels at very different velocities between different materials, even small amounts of contaminants (like dirt or air bubbles) can cause ultrasonic flow meters to produce readings that are less accurate than those of electromagnetic readers.

Vortex Flow Meters

Using a principle called the von Kármán effect, vortex flow meters measure water flow by tracking the differential pressure created by an obstacle in the path of the liquid. Changes in differential pressure create a vortex, hence the name of this type of meter.

While vortex flow meters don’t have mechanical parts and therefore require little maintenance, their readings are not highly accurate, especially at low flow rates.

Why Accurate Flow Meters Are Important

The degree of accuracy that an organization requires from a flow meter may vary. In general, however, the more accurate the flow meter, the more valuable it is to the business or agency.

That’s true across a variety of industries, all of which require accurate flow readings to ensure smooth business operations:

• Agriculture: In applications like agricultural irrigation, too much flow can flood a crop, leading to rot and a wasted harvest. Too little, which starves plants of water, is just as dangerous. Accurate flow meters remove the guesswork to ensure healthy, productive fields.
• Wastewater: Accurately measuring the flow of sewage and other types of wastewater is essential for preventing clogs, especially in systems where wastewater includes sludge as well as liquid effluent.
• Drinking water: Potable water systems require accurate flow measurements to ensure that the right amount of water reaches each branch and building on the system, even as water consumption rates vary across the systems.
• Cooling water: In settings like factories and data centers, cooling water plays a vital role in preventing equipment from overheating—but it only does so if cooling systems deliver just the right volume of water, which requires accurate flow meter readings.
• Industry: Industrial processes often require a variety of liquids, such as water, steam, and gas. Accurate flow meters ensure that businesses have the right volume and pressure of these materials to keep the plant floor humming smoothly.
• Oil and gas: To manage production and ensure adequate energy supply across large networks, the oil and gas industry must accurately measure flows, even when materials aren’t pure or when liquids travel very long distances.

How to Choose the Best Flow Meter

Given the varying levels of accuracy and degrees of maintenance required from different types of flow meters, choosing the best flow meter for your application can be challenging.

Here’s what to consider when evaluating your options:

1. Understand the Process
2. Consider the Media Being Measured
3. Determine Accuracy, Range, and Certification Requirements
4. Inspect the Meter Location and Installation Needs
5. Decide What Type of Output is Needed
6. Consult with a Technical Partner

• Read our full article and details of the Top 6 Factors to Consider When Selecting a Flow Meter