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Turbine Flow Meters

Turbine meters are a volumetric sensing devices that have high accuracies and ideal for low viscous fluids.  Unlike most flow measurement techniques, turbine flowmeters can work well in extreme high pressure and temperature fluid flows.  Turbine flow meters can measure both liquids and gases with best accuracies realized in liquid flow measurement.  

Turbine meters were introduced for flow measurement by Reinard Woltman, an 18th century German invetor. Today many domeistic water meters are called Woltman meters with perhaps millions in installed base around the world.  Turbine metes can be used both in liquid and gas applications.  Turbine meters consists of a multi-bladed rotor mounted at right angles to the flow in a pipe with a free-spinning bearings. The rotors are slightly smaller than the flow tube  and its speed of rotation is proportional to the volumetric flow rate of the fluid. The rotation of the blaes can be detected by solid state devices (reluctance, inductance, capacitive and Hall-effect pick-ups) or by mechanical sensors (gear or magnetic drives)

turbine diagram
Source: www.efunda.com
altmt flowmeter
altm sanitary flowmeter
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ALTMLF

Reluctance Pick-ups

In the reluctance pick-up, the coil is a permanent magnet and the turbine blades are magnetized  As each blade passes the coil, a voltage is generated in the coil. Each pulse represents a discrete volume of the fluid with the number of pulses per unit volume is called the meter’s K-factor.

Inductance pick-ups also come with a permanent magnet embedded in the rotor, as each blade passes the coil, it generates a voltage pulse representing a complete revolution of the rotor. The outputs of both pickup styles are continuous sine waves with the pulse train’s frequency proportional to the flow rate. Because at low flows, the pulse signal are very weak the distance between the pickup and associated display electronics or preamplifier must be short.

Capacitive Sensors

Capacitive sensors produce a sine wave by generating an RF signal that is amplitude-modulated by the movement of the rotor blades.

Hall-Effect Transistors

Hall-effect transistors change their state when they are in the presence of a very low strength (on the order of 25 gauss) magnetic field.  A very small magnets are embedded in the tips of the rotor blades. Rotors are typically made of a non-magnetic material, like polypropylene, Ryton, or PVDF (Kynar). Their signal output is a square wave pulse train, at a frequency proportional to the volumetric flow rate.

Having no magnetic drag, they can operate at lower flow velocities (0.2 ft/sec) than magnetic pick-up designs (0.5-1.0 ft/sec). The Hall-effect sensor also provides a signal of high amplitude (typically a 10.8-V square wave), permitting distances up to 3,000 ft. between the sensor and the electronics without amplification.

A typical turbine meter calibration curve is the relationship between fluid flow and K-factor (pulses/gallon). Turbine meters can be highly accurate between 0.5-1% with some as low as 0.1% of RD (actual flow), with linearity of  ±0.25% over a 10:1 flow range and a ±0.15% linearity in a 6:1 range. The repeatability is from ±0.2% to ±0.02% over the linear range.

All turbine flowmeters are calibrated indicating a K-factor in pulses per volume unit within the manufacturer’s accuracy band.  For better accuracy several K-factors for different portions of the flow ranges. More importantly,   the K-factor is applicable only to the fluid for which the meter was calibrated.

SmartmeasurementTM’ s ALTM turbine flow meters come in sizes ranging from 15-300mm (½” to 12”) and feature a wide turn-down with minimum uncertainty and a very repeatable output.  The ALTM is excellent for precise measurement of instantaneous flow of low-viscosity fluids such as tap and demineralized water, fuels, liquefied gases, light fuel oils, solvents, and pharmaceutical fluids.  The ATLTM series of turbine flow meters comes with the following flow bodies:

A typical turbine meter calibration curve is the relationship between fluid flow and K-factor (pulses/gallon). Turbine meters can be highly accurate between 0.5-1% with some as low as 0.1% of RD (actual flow), with linearity of  ±0.25% over a 10:1 flow range and a ±0.15% linearity in a 6:1 range. The repeatability is from ±0.2% to ±0.02% over the linear range.

Turbine Meter Calibration

All turbine flowmeters are calibrated indicating a K-factor in pulses per volume unit within the manufacturer’s accuracy band.  For better accuracy several K-factors for different portions of the flow ranges. More importantly,   the K-factor is applicable only to the fluid for which the meter was calibrated.

SmartmeasurementTM’ s ALTM turbine flow meters come in sizes ranging from 15-300mm (½” to 12”) and feature a wide turn-down with minimum uncertainty and a very repeatable output.  The ALTM is excellent for precise measurement of instantaneous flow of low-viscosity fluids such as tap and demineralized water, fuels, liquefied gases, light fuel oils, solvents, and pharmaceutical fluids.  The ATLTM series of turbine flow meters comes with the following flow bodies:

Have questions about our Turbine Meters? Contact the experts at SmartMeasurement today!

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Installation Methods

Primary Application

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Main Markets

Installation Methods

Primary Application

Special Features

Main Markets

Installation Methods

Primary Application

Special Features

Main Markets