Turbine flow meter

Turbine flow meters measure volumetric flow by letting the fluid spin a multi-bladed rotor, then counting the pulses from a magnetic pickup. They are the default choice for clean, low-viscosity fluids where you want high accuracy without paying Coriolis prices.

Which turbine meter fits your line

The split is by fluid, not by size.

• Gas turbine meters handle natural gas, LPG and compressed air. They need temperature and pressure compensation to convert actual volume into standard volume, so the transmitter usually carries those inputs. Range: DN25 to DN300, plus or minus 1.0 percent.
• Liquid turbine meters serve water, diesel, kerosene and light chemicals at plus or minus 0.5 percent with very low pressure drop. Range: DN4 to DN200.

What decides the model

Viscosity first. Above roughly 10 cSt the rotor stops responding linearly and the K-factor needs a viscosity correction that most datasheets do not mention. Above 20 cSt, stop looking at turbine meters.

Then flow range. Size the meter so normal flow sits in the upper two thirds of its range. A turbine meter run at a quarter of its maximum will sit outside its linear range and read badly, and no amount of calibration fixes that.

Then the practical items: a 20 mesh strainer upstream, about 10D of straight pipe, and enough back pressure to stop cavitation at the rotor tips.

Where they are the wrong answer

Steam, slurry, high-viscosity product and anything with entrained air. If your fluid is one of those, look at the vortex or electromagnetic families instead.

For the full working principle and K-factor curve, read how a turbine flow meter works.