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Coriolis Flow Meter Calculation: Sizing Math for Fluid Phase Shift Inertia
Quick Answer
Quick Answer: For a Coriolis meter sizing job, start with mass flow rate, density, viscosity, pressure drop, and pipe size. The phase shift inertia calculation is the core math that converts tube motion into mass flow. Send Silver Automation Instruments your pressure in bar, temperature in °C, pipe size DN, and flow range in kg/h for a sizing sheet.
Why Phase Shift Inertia Changes the Sizing Outcome
A Coriolis meter measures mass directly. The meter drives a tube at its natural frequency. Fluid mass flow changes the tube motion between two sensor points. That change is called phase shift. The fluid inertia resists the tube vibration. Because of this, the tube length, wall thickness, and sensor position all need to match the fluid density and flow range.
Here is the thing. Most engineers skip the inertia check and size only from line diameter. That produces a meter with weak phase shift at low flow. We have seen this on customer sites in Malaysia and Chile.
The Core Sizing Formula in Field Units
Use this simple form on site: Qm = K x Δt. Qm is mass flow in kg/h. K is the meter factor supplied by the factory. Δt is the phase shift time in microseconds. For volume flow use Qv = Qm / rho. Qv is volume flow in m3/h. rho is fluid density in kg/m3. A sizing program checks these values against velocity, pressure drop, and sensor signal strength.
In practice, a DN25 meter with water at 20 bar and 25 °C will produce a stable phase shift signal from 200 kg/h to 18000 kg/h. Below 200 kg/h the signal may be too small for custody transfer accuracy.
DN Selection and Real Flow Ranges
DN15 suits 0 to 6500 kg/h for water-like liquids. DN25 suits 0 to 18000 kg/h. DN50 suits 0 to 70000 kg/h. These ranges drop when viscosity goes above 100 cP or when gas density is below 10 kg/m3. A paint manufacturer in Vietnam oversized a DN50 meter for a 900 kg/h resin line. The phase shift signal became unstable. A DN15 meter corrected it.
For gas flow, do not use a liquid meter on a line with less than 5 bar. Low gas density reduces the Coriolis signal. For high pressure natural gas above 40 bar, a DN50 meter can handle 0 to 12000 kg/h in some installations.
Pressure Drop Calculation
Pressure drop depends on tube geometry, mass flow, and density. For a DN25 Coriolis meter at 12000 kg/h with water, pressure drop is usually 0.4 to 0.8 bar. At 20000 kg/h it can reach 1.6 bar. For fluids above 500 cP, pressure drop increases quickly. Check this before ordering because it affects pump size and back pressure.
Send Silver Instruments your viscosity in cP, density in kg/m3, and operating pressure in bar. We will return a pressure drop curve and a recommended model number.
Fluid Phase Shift Cases That Often Surprise Engineers
Two phase flow breaks the phase shift measurement. Gas bubbles in a liquid create random inertia changes. The meter may report a flow spike or zero. Two phase flow is common in batch dosing, CIP return lines, and hot condensate. We saw this on a dairy line in Indonesia with CIP fluid mixed with air. The totalizer became unstable. The fix was back pressure control and
Slurries with solid particles can also affect tube frequency. Size the meter with the actual slurry density, not the carrier liquid density.
Temperature Compensation and Density Output
The meter uses an internal PT100 sensor for temperature compensation. Density is calculated from tube frequency. A DN40 Coriolis meter often has density accuracy of 0.002 g/cm3 and temperature accuracy of 0.5 °C. If your process changes temperature from 25 °C to 120 °C, use density at the operating temperature. The transmitter can output mass flow, density, temperature, and volume flow over 4-20 mA HART or Modbus RTU.
Most engineers skip this part during sizing. They take density from a safety data sheet at 20 °C. Then they find a 3 percent error on a 90 °C chemical line.
Recommended Models for Common Sizing Ranges
Silver Instruments offers the SIC series Coriolis mass flow meter. For DN3 to DN10, use the SIC micro flow meter for 0 to 100 kg/h. For DN15 to DN80, use the standard SIC model with 4-20 mA HART, Modbus RTU, and local display. For DN100 to DN300, use the large line SIC model with a remote transmitter. ATEX Zone 1 is available for gas and chemical plants.
If you are not sure which model fits, send us the pipe size DN, fluid name, flow range, and pressure in bar.
FAQ: Coriolis Meter Sizing and Phase Shift Inertia
What data do I need for a Coriolis meter sizing calculation?
You need minimum and maximum mass flow, operating pressure in bar, temperature in °C, fluid density, viscosity, pipe size DN, and whether the fluid is gas, liquid, or slurry.
Does phase shift inertia change with fluid type?
Yes. The phase shift signal is stronger with high density liquids and weaker with low density gases. A gas meter often uses a larger sensor or higher gain settings.
Can I use one Coriolis meter for multiple products?
Yes, but check the worst case density and viscosity. A meter sized for water may not be stable with 0.8 cP solvent or 2000 cP syrup.
What is the typical turndown ratio for a Coriolis meter?
Most Coriolis meters handle 20 to 1 or better. Some Silver Instruments SIC models reach 50 to 1 for liquid mass flow. Verify turndown against your minimum flow, not just maximum flow.
How do I get a sizing calculation from Silver Instruments?
Call Tel: +86-25-68650347 or Whatsapp: +86-25-52155837. Send your pressure in bar, temperature in °C, pipe size DN, fluid name, and flow range in kg/h. We return a sizing sheet with pressure drop, accuracy, and model number.
Final Check Before You Order
Confirm meter orientation, back pressure, pipe vibration, and phase shift stability at minimum flow. For custody transfer or batch dosing, request an ISO 17025 calibration certificate. Silver Automation Instruments provides factory calibration reports with every Coriolis meter. Our site is flow-meter.com.au. We supply customers in Southeast Asia, Australia, Latin America, Africa, and the Middle East.
Send your pressure in bar, temperature in °C, pipe size DN, and flow range in kg/h. That is the fastest way to get a firm sizing calculation. You can also reach us on WeChat: +86 15365082610.
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