Application Cautions for Turbine Flow Meters

Turbine flow 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.