『Emerson Mass Flow Meter Installation Guidelines to Prevent Vibration and Multi-Phase Errors』Related information(v cone flow meter|rotary gas meter|gallon meter|gear meter|metal tube rotameter|glass tube rotameter|nutating disk meter|transit time ultrasonic flow meter|wedge flow meter|pd meters|hydraulic flow meter|ultrasonic water flow meter|water flow meter|air flow meter|magnetic water flow meter|oxygen flow meter|gas flow meter|argon flow meter|air velocity meter|gasoline flow meter|fuel flow meter|ultrasonic water meter|digital water meter|nitrogen flow meter|solid flow meter|Oxygen tank flow meter|digital water flow meter|diesel fuel flow meter|steam flow meter|02 flow meter|compressed air flow meter|oil flow meter|liquid flow meter)
Emerson Mass Flow Meter Installation Guidelines to Prevent Vibration and Multi-Phase Errors
Quick Answer: Coriolis mass flow meters lose accuracy when pipe vibration reaches the sensor natural frequency or when two phase flow enters the measuring tubes. The fix starts with rigid pipe supports within 2 pipe diameters of the meter body, minimum backpressure above 1.3 times vapor pressure, and a location away from pump discharge pulsation. Silver Automation Instruments supplies DN15 to DN300 Coriolis meters built for liquid, gas, and light slurry service.
Why Vibration Errors Appear on Coriolis Meters
Every Coriolis sensor uses oscillation to measure mass flow and density. An external vibration source with a frequency close to the drive frequency can add noise to the phase shift signal. We have seen this on customer sites many times. A water treatment plant in Malaysia installed a DN25 meter directly after a positive displacement pump. The reading jumped between 1.2 kg/h and 1.9 kg/h even at steady flow. Root cause was mechanical vibration from the pump body. The meter was not faulty.
Emerson installation guides identify 0.1 g to 0.5 g of pipe acceleration as a practical risk zone. Most standard Coriolis meters can tolerate small vibration. But pump cavitation, compressor pulsation, and control valve flutter cause wider errors. Avoid mounting the sensor on a cantilever pipe section. A longer pipe from the pump discharge with a support clamp reduces vibration at the sensor face.
Pipe Support Rules That Prevent Sensor Stress
Install rigid pipe clamps within 2 DN to 5 DN of the meter flanges. This rule applies for horizontal and vertical lines. For a DN50 Coriolis flow meter, that means a support point roughly 100 mm to 250 mm from each flange face. Do not let the meter body act as a pipe support. The sensor weight plus process fluid weight creates mechanical stress. Stress shifts the zero point and reduces repeatability.
Flexible hoses or expansion joints go on the outside of the supports, never directly on the meter flanges. A chemical batch plant in Vietnam used a rubber expansion joint directly downstream of a DN40 flow meter. Density value drifted by 0.018 g/cm3 every cycle. Moving the joint to the far side of the pipe clamp solved the drift. The meter passed calibration with a 0.12 percent mass flow error.
Multi-Phase Flow and How to Reduce It
Multi-phase flow means gas bubbles in liquid or liquid droplets in gas. For Coriolis meters, small bubbles change the density reading and cause large mass flow spikes. A palm oil producer in Indonesia measured crude oil with entrained air after a storage tank. Mass totalizer error reached 4 percent before the line was de-aerated. The fix involved raising tank level and adding a backpressure valve.
Maintain downstream backpressure at least 1.3 times the liquid vapor pressure at operating temperature. For water at 25 °C this is easy. For hot hydrocarbons at 140 °C this needs a control valve or an orifice plate. If your process contains dissolved gas, install a degassing vessel upstream of the meter. Keep the meter full of liquid. Vertical upward flow helps sweep gas pockets out of the sensor tubes.
Orientation and Process Connections
Liquid lines with occasional gas slugs perform better in
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Check process connection alignment. Flange bolt torque must be even. Uneven torque causes body twist and zero shift. For high temperature service above 150 °C, allow the meter to reach thermal equilibrium before zeroing. A zero check after installation takes ten minutes and prevents offset errors.
Electrical Grounding and Signal Cables
Route the sensor cable away from variable frequency drives, motor cables, and power lines. Use shielded twisted pair cable. Ground the shield at one end only. This avoids ground loop noise. An OEM skid builder in Thailand had a DN80 Coriolis meter placed near a 15 kW motor cable tray. The flow reading showed a 0.4 kg/h noise floor until the cable was rerouted 300 mm away.
Silver Instruments Products and Ordering Data
Silver Automation Instruments supplies the SLW series Coriolis mass flow meter for DN15 to DN300 lines. The meter handles liquid flow ranges from 0.2 kg/h to 600 t/h depending on line size. Standard outputs include 4-20 mA HART, pulse, and RS485 Modbus. Accuracy is 0.1 percent to 0.2 percent of rate for liquids. The sensor is available with 316L stainless steel wetted parts and Ex d pressure transmitter options for ATEX Zone 1 gas or dust areas.
If your site has vibration or two phase flow concerns, send us the following process data. Pipe size in DN, fluid type, flow range in kg/h or t/h, operating pressure in bar, temperature in °C, and whether the fluid has dissolved gas or solids. Our engineers will recommend a meter size and mounting kit.
Contact Silver Automation Instruments.
Tel: +86-25-68650347
Whatsapp: +86-25-52155837
WeChat: +86 15365082610
FAQ
What is the minimum straight run for a Coriolis mass flow meter?
Coriolis meters do not require long straight runs. But you should keep the sensor at least 2 DN away from pump discharge and control valves. This reduces swirl and pulsation.
How do I know if vibration is causing my flow error?
Look for unstable readings at constant flow, a noisy density value, or errors that change when the pump speed changes. A zero check with no flow can also show drift above 0.05 percent.
Can a Coriolis meter measure two phase flow?
Most standard Coriolis meters are designed for single phase or stable bubbly flow. For high gas void fraction above 5 percent, special two phase algorithms or a phase separator may be needed.
What backpressure should I keep for liquid flow measurement?
Keep downstream pressure at least 1.3 times the vapor pressure of the liquid at operating temperature. This prevents cavitation and gas breakout inside the measuring tubes.
Does Silver Instruments provide installation support?
Yes. Send your process data to Silver Automation Instruments. We can review your piping layout and give you a written recommendation for supports and orientation.
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