Turbine Flow Meter (axial turbine) was created by Reinhard Woltman and is an accurate and reliable flow meter for liquids and gases. This flow meter uses the mechanical energy of the flowing fluid to rotate a “pinwheel” (rotor) translating the mechanical action of the turbine’s rotation in the flow of the fluid around its shaft into a readable flow level (gpm, lpm, etc.) The turbine tends to follow the flow journey around it.
Blades on the rotor are tilted at a certain angle like a propeller, to convert energy from fluid flow into rotational energy. The rotor shaft rotates on the bushings/bearings where when the fluid moves faster, the rotor rotates proportionally faster.
This type of flow meter is widely used for the measurement of natural gas and liquid flow. Although measurements with turbine flow meters are less accurate than measurements with jets and displacement at low flow levels, the measuring element does not occupy or is disconnected from the entire flow path.
Characteristics of Turbine Flow Meter
The rotation of the shaft of the Flow Meter Turbine can be felt mechanically or by detecting blade movement. Blade movement is detected magnetically, with each blade or embedded part of the metal producing pulses.
When the liquid moves faster on the turbine flow meter, it will produce more pulses that will be proportional to the speed of fluid flow. The Pick-up sensor on the turbine flow meter will process the pulse signal to determine fluid flow. Transmitters and motion systems are available to capture flow in both forward and backward current directions.
The pick-up sensor produces pulses as fast as its rotating impeller, this provides a very fast reaction time making this type of flow meter perfect for batching applications. The pulse produced by the pick-up sensor is a pulse per unit volume, also referred to as the k-factor.
Turbine Flow Meter function
Turbine flow meters can be used to measure the flow speed of liquids, gases and vapors in pipes, such as hydrocarbons, chemicals, water, cryogenic fluids, air, and industrial gases. It should be considered in determining the turbine flow meter should be careful on dirty liquids (containing garbage, sand and other solids).
Because the dirt that passes through it will be able to inhibit accuracy and will even fail because the rotor can not rotate due to snagged dirt. Likewise for liquids that are non-lubricating, because the flowmeter can become dysfunctional or its accuracy deviates too far because there are turbine flowmeters have grease fittings for use in liquids that do not have lubrication properties.
In addition, turbine flow meters designed for specific purposes, for example for natural gas services, can often operate at a limited temperature range (e.g. up to 60ºC) where operation at higher temperatures can damage the flowmeter.
This flow meter is better if applied to sanitary fluids, relatively clean, and corrosive in size up to about 24 inches. Small turbine flowmeters can be installed directly in the pipe, but the size and weight of larger turbine flowmeters may require a strong foundation installation.
Types of Turbine Flow Meters
Turbine Flow Meters are generally available from 1.5 inches to 12 inches or larger pipe sizes. Turbine bodies are usually made of bronze or iron. The inside of the turbine can be plastic or non corrosive metal, the turbine is accurate under normal working conditions.
In fire extinguishing hydrants there is a special type of portable turbine flow meter that is placed on the hydrant to measure the hydrant water output. It is usually made of lightweight aluminum with a capacity of 3 inches. It is often used for the purposes of measuring water used in construction, filling pool water or where permanent measurements have not been installed.
At this time has developed with a variety of basic materials / matrial from non metal, carbon steel, brass, to stainless steel.
Turbine Flow Meter Application
The application of turbine flow meters is less accurate at low flow speed levels because it can slow the rotor rotation. Meanwhile, for the installation of turbine flow meters there are inline using thread flange connections and there are also those who use the insert method can be known as insertion turbine flow meter.
Baca Juga : Gas Turbine Flow Meter(Opens in a new browser tab)
Likewise, for fluid flow speeds that are too high in flow meter turbines can cause thirst in bushings or bearings or shaft rotors therefore should be in operating flowmeters approximately 5 percent higher than the maximum flow speed as determined by manufacture.
In some applications, bearing replacement may need to be done routinely and bergbat at high maintenance costs. Likewise, applications in dirty fluids should generally be avoided so as to reduce the possibility of life time flowmeter and damage to bearing / bearing / shaft rotor, because flowmeters turbines have moving parts that experience wear and tear according to the time of use.
As for the material aspect of this type of turbine flow meter there is quite a variety of carbon steel materials, stainless steel both food grade and not that are widely used for the food industry even from non-metal materials such as PVC, PP, Teflon and others that are widely used for chemical flow meters.
Important Factors in the Operation of Turbine Flow Meters
The flow direction is generally straight directly through the gauge, allowing for higher flow levels and less pressure loss than the broad commercial user measurement type, fire extinguisher and as the parent measurement for the water distribution system.
Advantages of Turbine Flow Meter
Turbine flow meters have several advantages when compared to other types of flow meters. The advantages in question include:
- Has a turndown ratio of up to 35:1
- Wide flow flow rangeability, including for low flow rates
- Good level of accuracy
- Simple construction but has good durability
- Ease of installation and maintenance
- Flexible connection to other flow instruments
- Can operate in a variety of temperature and pressure conditions
- Low pressure reduction in the turbine.
Lack of Turbine Flow Meter
Apart from all the advantages of this flow meter as written above, this flow meter certainly also has some shortcomings that can be considered. Some of the shortcomings in question such as:
- Not suitable for handling liquids with high corrosive levels
- The presence of bubbles in the liquid can affect accuracy.
- Requires constant back pressure to prevent cavitation (air bubbles)
- Sensitive to changes in fluid viscosity
- Requires a straight pipeline upstream and downstream of the turbine meter so that the vortex in the liquid can disappear
- May not be able to function properly in high-vicosity fluids where the flow profile is layered
- For accuracy requires a turbulent flow profile where the fluid speed consistently passes through the overall diameter of the pipe.
- Not suitable for liquids with solid object content in it (should be installed a filter on the upstream before the liquid enters the flow meter).