Current position > Contact Us
A Coriolis mass flow meter measures mass flow directly by detecting the phase shift between two ends of an oscillating tube. When fluid flows through the tube, Coriolis force twists the tube and creates a time difference in the inlet and outlet vibration signals. That time difference is linear with true mass flow in kg/h. If you are evaluating a meter for a process line, send your fluid name, flow range, pressure, temperature, and pipe size to Silver Instruments for a specific model and price.
Think of a twin tube design from DN15 up to DN150. A drive coil shakes the tubes at their natural frequency, usually between 80 Hz and 1200 Hz depending on tube size. When flow is zero, the inlet and outlet sides cross the zero position at the same moment. Two electromagnetic sensors or optical sensors detect the sine wave at both sides. With no flow, the signals overlap. With flow, the fluid has inertia. The tube on the inlet side lags and the outlet side leads. That lag is a phase shift measured in microseconds. In a DN25 meter with water at 1000 kg/h, you may see a phase shift in the range of 10 to 15 microseconds. That small time offset is enough for the transmitter to calculate mass flow to better than 0.1 percent of rate on many liquid applications.
Here is the thing. The twist angle is tiny, often less than 0.01 degree. You will not see it with your eyes. The electronics do not need a visible movement. They measure the timing between two sine waves with a precision clock. This is why a Coriolis meter can measure very low flow and very high flow on the same pipe size without wearing parts.
The Coriolis force depends on the mass of fluid moving through the vibrating tube. A high density liquid at low velocity can generate the same Coriolis twist as a low density gas at high velocity. The meter does not care if the volume is small. It cares about mass inertia. This is why a Coriolis meter reads kg/h directly. You do not need a separate pressure transmitter and temperature transmitter to correct for density. The meter also measures density from the oscillation frequency. The tube frequency drops when heavier fluid fills the tube. A built in PT100 sensor measures process temperature and compensates the tube stiffness.
Most engineers skip this part. If your product density changes, a volume flow meter will make you compensate again and again. A Coriolis meter avoids that correction loop. We have seen this with a food processor in Thailand. They mix fruit pulp with different sugar content every batch. A magnetic flow meter measured volume, and the control room had to convert volume to mass with a density table. The table was never accurate. A Silver Instruments SIC-M Coriolis meter on the same DN40 line reported kg/h directly and removed that calculation.
The wetted parts are usually 316L stainless steel. For acids, caustic, or seawater, select Hastelloy C22 or super duplex. Process temperature ratings go from minus 200 degrees C up to 200 degrees C, and some high temperature versions go to 350 degrees C. Pressure ratings often reach 100 bar on DN15 to DN50. Outputs include 4-20 mA HART, pulse for batch control, and Modbus RTU. For oil and gas installations in the Middle East, specify ATEX Zone 1 or IECEx. Silver Instruments can also supply a remote transmitter if the pipe is hot or if vibration is high.
Do not install a Coriolis meter on a thin unsupported pipe that can shake. The meter is a mass measurement device, but external vibration can still introduce noise. Use rigid pipe supports on both sides. For liquid service, keep the tubes full. For gas service, avoid liquid slugs because they cause a short high amplitude noise spike. A paint manufacturer in Vietnam learned this when they first installed a meter without a strainer. Hard pigment chunks hit the tube and caused a spike in the drive signal. After adding a 60 mesh strainer, the readings settled. The meter did not have moving parts in the flow path, but the tube still reacts to impact.
Silver Instruments Coriolis mass flow meters are used in oil and gas, water and wastewater, chemicals, food and beverage, and marine fuel transfer. Common fluids include diesel, palm oil, brine, caustic soda, molasses, whey concentrate, sulfuric acid, and LPG. A desalination plant in Oman measures brine with a DN100 Hastelloy C22 meter because the salinity is high and the flow range is wide. A dairy plant in Thailand measures whey concentrate on a DN25 meter with 0.1 percent accuracy. A chemical distributor in Singapore uses a DN50 meter for solvent loading with 4-20 mA HART connected to a batch controller.
The main data needed for sizing are flow range in kg/h, process pressure in bar, process temperature in degrees C, pipe size in DN, fluid viscosity in cP, and hazardous area certification. A DN15 meter handles low flow dosing down to 1 kg/h. A DN50 meter handles a typical solvent transfer line up to 30000 kg/h depending on density. A DN100 meter handles brine or sludge flows. If you give us these details, we can recommend a model from the Silver Instruments SIC-M series.
Send us your flow range in kg/h, pressure in bar, temperature in degrees C, pipe size in DN, and fluid name. Email through the flow-meter.com.au contact page or call Silver Automation Instruments at Tel: +86-25-68650347. You can also reach us on Whatsapp: +86-25-52155837 or WeChat: +86 15365082610. We will reply with price, lead time, and a datasheet.
What does phase shift mean in a Coriolis flow meter?
The phase shift is the time difference between the inlet and outlet vibration signals. With flow, Coriolis force twists the tube. The outlet side crosses zero before the inlet side. The transmitter converts this microsecond time lag into mass flow.
Does a Coriolis meter need pressure and temperature compensation?
For mass flow, no. The meter reads mass directly. You still get a PT100 temperature sensor for process temperature output. Some models compensate tube stiffness with temperature, but the flow reading does not need pressure or density compensation.
Can a Coriolis flow meter measure gas and liquid with the same meter?
Yes, many models can switch between liquid and gas. The accuracy class changes. Liquid accuracy is often 0.1 percent of rate. Gas accuracy is often 0.35 to 0.5 percent. You need to specify the gas density range for sizing because gas needs a larger tube amplitude or different sensor gain.
What is the minimum straight pipe run for a Coriolis meter?
Most installations do not need long straight runs because the meter reads mass directly. You still want to avoid sudden expansion, cavitation, and two phase flow. A common practice is 0D upstream and 0D downstream for a tight skid, but you must keep the sensor full and avoid air pockets.
Which wetted materials are available?
Standard is 316L stainless steel. For aggressive fluids, ask for Hastelloy C22, super duplex, or titanium. For food grade, use a surface finish of 0.8 Ra or better. For seawater desalination, Hastelloy C22 or super duplex is common.
