Advantages Turbine Flowmeter
The cost is moderate.
Very good at clean,
Low viscosity fluids of moderate velocity and a steady rate.
Turn down is very good as it can read very low compared to the maximum flow.
They are reliable if put in a clean fluid especially if it has some lubricity.
AGA and API approved for custody transfers.
Wide flow rangeability including low flow rates
Turndown ratio is up to 35:1
Good level of accuracy at an economic price
Simple, durable construction
Easy to install and maintain
Flexible connection to flow instruments for flow control
Wide variety of process connections
Turbine meters can operate over a wide range of temperatures and pressures
Low pressure drop across the turbine
Provides a convenient signal output
Disadvantages Turbine Flowmeter
They do cause some pressure drop where that may be a factor such as gravity flows.
Not reliable for steam.
Bearings wear out problem.
Requires constant backpressure to prevent cavitation
Accuracy adversely affected by bubbles in liquids
Turbine meters can be used with clean liquids and gases only (may need to install a strainer upstream to prevent damage from particulates)
Not applicable for measuring corrosive fluids
Requires a turbulent flow profile (consistent fluid velocity across the pipe diameter) for accuracy
Sensitive to changes in fluid viscosity
Require a straight run of pipe before and after the turbine meter to allow swirl patterns in the flow stream to dissipate
May not function properly with high viscosity fluids where the flow profile is laminar
Applications
In order of magnitude from largest to smallest,
These are used in oil and gas,
Water and waste water,
Gas utility,
Chemical,
Power, food and beverage
Aerospace
Pharmaceutical,
Metals and mining
Pulp and paper.
Cautions for Turbine Flow meters
Turbine meters are less accurate at low flow rates due to rotor/bearing drag that slows the rotor. Make sure to operate these flow meters above approximately 5 percent of maximum flow.
Turbine flow meters should not be operated at high velocity because premature bearing wear and/or damage can occur.
Be careful when measuring fluids that are non-lubricating because bearing wear can cause the flow meter become inaccurate and fail.
In some applications, bearing replacement may need to be performed routinely and increase maintenance costs.
Application in dirty fluids should generally be avoided so as to reduce the possibility of flow meter wear and bearing damage.
In summary, turbine flow meters have moving parts that are subject to degradation with time and use.
Abrupt transitions from gas flow to liquid flow should be avoided because they can mechanically stress the flow meter, degrade accuracy, and/or damage the flow meter.
These conditions generally occur when filling the pipe and under slug flow conditions. Two-phase flow conditions can also cause turbine flow meters to measure inaccurately.