Applications for a Turbine Flow Meter

Turbine Flow Meter Overview:

A turbine flow meter is a volume sensing device. As liquid or gas passes through the turbine housing, it causes the freely suspended turbine blades to rotate. The velocity of the turbine rotor is directly proportional to the velocity of the fluid passing through the flow meter.

The external pickoff mounted on the body of the flow meter, senses each rotor blade passing, causing the sensor to generate a frequency output. The frequency is directly proportional to the volume of the liquid or gas.

Either a magnetic or modulated carrier (RF) pickup can be used to sense the rotational speed of the turbine rotor.

Depending on your flow meter application, there are many types of turbine flow meters to choose from. And after understanding the application several factors come into effect when choosing a flow meter, such as:

  • Fluid Type
  • Viscosity
  • Connection
  • Pipe Sizing
  • Process Temperature (min & max)
  • Flow Range (min & max)
  • Pressure Range (min & max)
  • Accuracy Range
  • Specific Application

If you need volumetric total flow and/or flow rate measurement, a turbine flow meter is the ideal device. Turbine flow meters are used in a wide variety of liquid and gas flow sensing applications. They can be built to endure high pressure, and high and low temperatures. They offer a high turn-down with minimum uncertainty and excellent repeatability. Turbine flowmeters are also simple to install and maintain only requiring periodic recalibration and service.

Specifications:

Accuracy is generally expressed as a percentage of true volume, measuring how close the instrument indicates actual flow.

Repeatability is determined on how well the flow meter can indicate the same reading whenever the same flow conditions exist. It also ensures quality measurement of fluids over a wide range of flow rates, temperatures, compositions and viscosities.

Depending on the type of turbine flow meter, the specifications vary.

Turbine Meter – (FM Series)
Tangential Turbine Flowmeter – (FMT Series) capable of measuring extremely low flow rates.
Insertion Turbine Flow Meter – (FMP Series) used economically usually in pipes 6” and larger in diameter

Liquid Service
Flow Range: 0.03 – 15,000 GPM
Accuracy:

±0.5% Linearity over Normal Range 10:1 Turndown
±0.05% Repeatability
Sizes: 1/4″ to 72″
Gas Service
Flow Range: 0.25 – 1500 ACFM
Accuracy:

±0.1% Linearity over Normal Range 10:1 Turndown
±1% Repeatability
Sizes: 1/4″ to 72″

Industries:

Turbine Flow Meters Pros and Cons

Turbine flow meters are the preferred method for clean, filtered and low viscosity fluids. These meters also are known for their accuracy. The inner workings and design of these meters are very well known within the industry. However, like anything, there are pros and cons of using turbine flow meters. 

Let’s start with the pros. Turbine flow meters are low cost and easy to install and operate. They rarely have performance issues, as their technology is rather simple. These meters are great for gases and liquids and have a relatively wide envelope of flow to them. 

Now the drawbacks. They require frequent calibration. Their installation has to be exact and precise to avoid any errors. They require the fluids passing through to be clean. There are also issues with cavitations and errors due to viscosity changes. 

 

For more on this subject visit AZO HERE

 

 

Types of Fluid Flow Meters

Types of Fluid Flow Meters

 

Having options is always a great thing. There are many different types of flow meters on the market. The common principles of flow meters are differential pressure, velocity, positive displacement, mass, and open channel. Along with the principles the different types of meters are orifices, venturies, nozzles, rotameters, pitot tubes, calorimetrics, turbine, vortex, electromagnetic, doppler, ultrasonic, thermal and coriolis.

Because there are so many different types, making sure you have the right one for the project is imperative. Each meter does different things and reacts differently depending on what you need it for. The basic goal is to get the most accurate reading. 

For more information on what all these flow meters do visit Engineering Toolbox HERE

 

Understanding Turbine Flow Meters

Turbine flow meters are quite an interesting mechanism. The way they measure flow based on velocity is fascinating. This video is a great understanding of what and how turbine flow meters do what they do. The descriptions and graphics really tell you what you need to know about the inner workings. 

For more informative videos visit McGraw Hill HERE

How Turbine Flow Meters Work

How Turbine Flow Meters Work | Flowmetrics

Turbine flow meters are a popular way of measuring liquid and natural gas flow. Also known as an axial turbine, this type of meter consists of a turbine wheel that is placed in the stream of the flow. The flow pushes the meter’s angled blades, causing the turbine to rotate. Flow rate can be determined based on the turbine’s rotation rate once it becomes steady. The rate of rotation is typically picked up by electronic coils that are connected to the meter’s housing, and then turned into readings that can be accessed by the user.

Minimal Flow Disruption

One advantage of a turbine flow meter is that it offers minimal disruption to the flow. Because the flow can continue right through the turbine, there is little pressure loss and speed can remain fairly high. For this reason, they are often preferred for purposes water distribution, fire protection and for large commercial projects, where a high rate of flow and high pressure is desirable. On the other hand, applications where flow rates are low will typically use meters that are considered more accurate but tend to impede flow rates, such as displacement meters.

Ensuring Maximal Accuracy

Turbine meter measurements can be affected severely by factors such as flow profile, temperature and flow rate and content. Strainers installed near the meter can help protect the turbine from debris that could damage it. Depending on specific conditions, users may choose to put additional protective measures in place to ensure maximally accurate and consistent flow measurements.

New Developments

With today’s advancements in technology, turbine flow meter accuracy has also improved. Increased sensitivity allows for the precise measurement of even extremely low flow rates in some models. Manufacturers also continue to develop blade and rotor materials that are highly sensitive, durable and less vulnerable to drag and other factors that have traditionally decreased accuracy. Some types of turbine meters are also able to measure and record variations in flow with a high degree of precision. Another way in which flow meter makers have reduced inaccuracy is by reducing the rotor’s inertia. A high inertia would keep the rotor spinning fast even after flow had decreased, leading to inaccurate results. A low inertia lets the turbine reduce speed together with the flow.

Maintenance and Calibration

Regular inspection and calibration is essential to keeping a turbine flow meter accurate. For best results in calibration, test your meter under conditions that are as close to normal operating settings as possible, keeping the flow composition, rate and temperature substantially similar. In addition to regularly scheduled inspections, check your meter in the event that you are receiving inconsistent or unusual readings that cannot be explained by actual variations in the flow.

Malfunction may occur as a result of regular wear and tear, impact by debris, corrosion or buildup of dirt or viscosity. Problems may also happen if your meter is calibrated incorrectly or was not properly installed. While some problems can be fixed by recalibrating or performing minor repairs, others may necessitate partial or total replacement. If you are using an older turbine flow meter, be aware that recent developments have substantially improved measurement accuracy; thus, it may be wise to invest in an updated model.

 

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