A turbine meter is a flow meter that uses a free-spinning bladed rotor placed in the flow stream: the fluid pushes the blades and the rotor spins at a rate proportional to flow velocity. Counting the rotor's revolutions gives volume. Turbine meters offer high accuracy and wide rangeability, and are common in both gas (AGA 7) and clean-liquid service.
Turbine Meter in one line: A turbine meter measures flow with a rotor that spins in proportion to fluid velocity; each blade passage generates a pulse, and the pulse count multiplied by the meter's K-factor gives volume.
Fluid entering the meter passes through the rotor, whose angled blades convert linear flow into rotation. A pickup - typically a magnetic sensor - detects each blade tip passing and produces an electrical pulse train whose frequency is proportional to flow rate. Each meter has a calibrated K-factor (pulses per unit volume), so the flow computer divides the pulse count by the K-factor to get volume, and pulse frequency to get instantaneous rate.
Because output is essentially linear with velocity, turbine meters have much better turndown than orifice meters - often 10:1 or wider - and good repeatability. That accuracy depends on a clean, single-phase, well-conditioned flow: the meter needs adequate straight run upstream, benefits from flow conditioning, and is sensitive to debris, sudden overspeed, and bearing wear. Gas turbine meters are similarly proportional but require pressure and temperature correction to report at standard conditions.
In gas service, turbine meters are widely used for custody and check measurement under AGA Report No. 7, which covers installation, the pulse-to-volume relationship, and correction to base conditions. In liquid service they meter clean crude, refined products, and NGLs, and are proved against a prover to establish a meter factor for custody transfer under API MPMS.
Their linear pulse output and wide rangeability make them attractive where flows vary a lot, and their moving rotor makes maintenance and periodic re-proving important because bearing wear shifts the K-factor over time. A turbine meter usually feeds a flow computer that counts pulses, applies the K-factor and pressure/temperature corrections, and totalizes. That flow computer typically exposes rate and totals over Modbus, so a cloud SCADA platform can trend flow, watch for a K-factor that has drifted since the last proving, and alarm on abnormal readings that suggest a fouled or damaged rotor.
The K-factor is the calibrated number of output pulses the meter produces per unit of volume. Dividing the total pulse count by the K-factor yields volume, and pulse frequency divided by K-factor gives flow rate. Because bearing wear and buildup change the K-factor over time, custody turbine meters are periodically re-proved.
A turbine meter's output is essentially linear with velocity, giving wider turndown and good low-flow accuracy, whereas an orifice meter follows a square-root relationship and loses accuracy at low flow. The trade-off is that a turbine has a moving rotor and bearings that wear, so it needs more maintenance and periodic re-proving than a static orifice plate.
AGA Report No. 7 governs turbine meters in natural gas service, covering installation requirements, the pulse-to-volume relationship, and correction to base pressure and temperature. For liquid custody service, turbine meters are handled under the API Manual of Petroleum Measurement Standards and proved against a prover.
This page references the protocol specifications published by the organizations below. Editions, product capabilities, and documentation change over time - confirm current requirements and specifications directly with the source.
Last reviewed: July 27, 2026. Merobix is not affiliated with, endorsed by, or sponsored by these organizations; their names are used only to identify the standards and products discussed.
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