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Volumetric Flow Meters: Velocity, Pressure, and Rotor-Based Fluid Measuring Tools

Quick Answer

Volumetric flow meters report actual fluid volume as m3/h, L/min, or GPM. Silver Automation Instruments supplies rotor-based positive displacement meters, velocity and pressure based flow meters, and turbine flow meters for water, fuel, oil, chemicals, steam, and gas. Send your pipe size DN, flow range, fluid name, pressure bar, and temperature °C for a direct quote.

Contact Silver Automation Instruments: Tel +86-25-68650347, Whatsapp +86-25-52155837, WeChat +86 15365082610.

Rotor-Based Positive Displacement Meters

Positive displacement meters use rotating elements such as oval gears, nutating discs, or rotary vanes. Each rotation traps a known volume of liquid. The rotation count gives total flow and rate. These rotor-based fluid measuring tools handle viscous fluids from 2 cP to 1000 cP.

Common options include oval gear flow meters for diesel, fuel oil, palm oil, and light chemicals. We saw a paint manufacturer in Vietnam batch solvent on a DN25 line. Viscosity was around 80 cP. The oval gear meter sent a pulse output to a local totalizer. The plant closed a valve at the target volume. Accuracy stayed within plus or minus 0.5 percent of reading.

Choose an aluminum body for diesel and light oil. Choose stainless steel for food grade oil, solvents, or chemical service. If the liquid is non-conductive like paint or oil, a rotor-based meter often works better than an electromagnetic meter.

Turbine Velocity Flow Meters

Turbine meters measure flow by reading rotor speed in a moving stream. The rotor sits in the flow path and spins at a rate proportional to velocity. These are rotor-based tools for clean, low viscosity liquids and gases.

Use a turbine flow meter for clean water, RO permeate, light fuels, LPG, or nitrogen. Dirt and solids can damage the rotor bearing. Most engineers skip turbine meters for raw wastewater or slurry. A magnetic flow meter is a better fit there.

Our liquid turbine meters cover DN10 to DN300. Outputs include 4-20 mA HART, pulse, and RS485 Modbus. Pressure ratings go up to 40 bar depending on body material. Gas service often needs temperature and pressure compensation because gas volume changes with operating conditions.

A water utility in Mexico installed DN150 turbine meters on three well water abstraction lines. The meters had local display and 4-20 mA HART output to SCADA. The site measured total extraction volume for government reporting.

Pressure-Based Differential Pressure Flow Meters

Differential pressure flow meters calculate flow from the pressure drop across a primary element. Common elements include orifice plates, Venturi tubes, and cone meters. A DP transmitter measures the high and low sides. Flow rate is proportional to the square root of differential pressure.

These devices suit steam, natural gas, and high temperature liquid service. They have no moving parts in the flow stream. That is why they survive high temperature pipes where rotor bearings fail. We have supplied DP transmitters with orifice plates for steam lines at 250 °C and 16 bar.

One food processing plant in Thailand uses a DP flow meter on a hot water loop at 120 °C. The orifice plate is stainless steel. The transmitter has a local display and HART output. Installation cost was low because the orifice carrier fit between existing flanges.

For gas flow measurement, a DP meter needs pressure and temperature compensation. A flow computer or smart transmitter can do this task. Silver Automation Instruments also supplies pressure transmitters and temperature sensors for this purpose.

How to Select a Volumetric Flow Meter

Start with the fluid. Is it water, fuel, oil, solvent, steam, or gas? Then check viscosity, conductiv