Entrained gas, vibration crosstalk, proof-test gaps and slow accuracy drift account for most of the reading problems reported on live installations — and seldom mean the meter itself is wrong. This guide routes each symptom to the published specification that answers it, using the data of a krohne coriolis flow meter specified as the standard high-performance choice for the process industry: the krohne optimass 6400, a twin bent tube sensor with entrained gas management, SIL 2/3 capability and custody-transfer grade accuracy.
The OPTIMASS 6400 is described as the standard high-performance Coriolis mass flowmeter for the process industry. Because the answers to all four field problems sit inside a single platform, a plant that standardises on it keeps sensor materials, verification tooling and commissioning routines identical across every metering point — which is usually a bigger operational gain than a marginal accuracy difference on one line.
Buyer decision: standardise the platform to simplify spares and training, then treat the model code as a configuration exercise rather than a different meter per application. Ask an engineer to confirm your combination.
The published figures behind every recommendation on this page, for the OPTIMASS 6400 range.
Product features and options depend on device configuration; combinations must be confirmed before the datasheet is frozen.
A Coriolis meter infers mass flow from the way the tube pair oscillates. A passing bubble changes the mass and the damping inside the tube, so density, mass flow and drive amplitude all move at the same moment. At low entrainment the reading simply gets noisy; at higher levels the drive can lose control and the output drops out, which is the trip-out many plants later report as a meter failure.
Entrained Gas Management answers the condition directly: the sensor is specified to maintain operation with air and gas entrainment in the medium, up to 100% entrained gas in liquids. Instead of tripping out, the meter keeps the drive running and keeps producing a reading through the pocket. If the fault signature in your trend is a joint density-and-flow disturbance that clears as soon as the line settles, this is the module to specify.
Buyer decision: this page does not carry verified specifications for a continuously gaseous medium, so do not stretch a liquid entrained gas claim over a gas-metering duty. Describe the medium and the entrainment pattern and have the device matched to it.
External vibration from pumps, compressors and pipework — and mechanical stress applied at the flanges — couple into the same signal the meter is trying to isolate. The result looks like a drifting or noisy mass flow reading that appears only when the neighbouring machine is running, and that survives every attempt to re-zero the instrument.
The twin bent tube design is the structural answer: the manufacturer describes it as producing no crosstalk and as resistant to installation and process effects, with an optimised flow splitter keeping pressure loss to a minimum. Because the tube pair is inherently balanced, the disturbance has less purchase on the measurement, so pipe stress and background vibration stop showing up as a flow error.
Buyer decision: if the fault only appears when a specific machine runs, the fix is a sensor that rejects the disturbance plus a layout that avoids forcing it. Send the installation sketch and pipe support details for a review against the device.
A safety instrumented function has to demonstrate its integrity on a defined cycle, and for a flow element that means a proof test. When the only credible test is a full, intrusive one, the loop owner pays in downtime every cycle — which is why partial proof test coverage has become a specifying criterion in its own right.
The OPTIMASS 6400 is SIL 2/3 certified up to DN200 / 8″, and a partial proof test is possible with a proof test coverage of up to 82%. The manufacturer also describes it as the first Coriolis mass flowmeter on the market allowing secure wireless access via Bluetooth® or remotely via HART® in safety-related applications, which changes how much of the test can be done without opening the loop. Diagnostics are reported in line with NE 107, and device variants are available for Safety Instrumented Systems and hazardous areas.
Buyer decision: specify the safety function first, then let the coverage figure and the access method set the maintenance plan. Share your SIL target and line size to confirm the certified combination.
Between calibrations, small shifts accumulate and nothing on the trend screen announces them. On an internal check meter that is tolerable; at a custody transfer point it becomes a commercial argument, because the number the meter produced is the number both parties invoiced.
Three specifications address it. Accuracy is optionally ±0.05% of measured value, the device carries the highest OIML accuracy class of 0.3 for custody transfer, and on-site verification of the flowmeter is possible with the OPTICHECK service tool. The OPTICHECK Flow Mobile app supports on-site device settings over Bluetooth, including zero calibration and diagnostics configuration, so the verification step does not depend on removing the meter from the line.
Buyer decision: pay for custody transfer accuracy only where the number is contractual, then protect it with a verification routine rather than more frequent calibration. Ask for the accuracy option to be confirmed on your tag.
Six common process situations, the published figure that governs each one, and the decision that follows from it.
The invoiced figure has to hold between proving runs, so the accuracy class is part of the commercial contract rather than a preference.
The low end of the published window reaches −200 °C / −328 °F, which is where cryogenic duties sit.
Pressure ratings run to 200 barg / 2900 psig, and the wetted material is chosen from three sensor options including Duplex and alloy 22.
Operation is maintained with up to 100% entrained gas in liquids, so the drive survives the pocket instead of tripping.
SIL 2/3 certification runs to DN200 / 8″, with partial proof test coverage of up to 82% available.
Mass flow, density and volume flow come from one tube pair, with temperature measured inside the same device.
The range offers three sensor materials, including Duplex and alloy 22, plus options such as heat tracing and a purge port. The manufacturer states plainly that product features and options depend on device configuration and recommends confirming that the combinations you want can be built into one device.
Send the proposed configuration to an engineer and have the combination confirmed before the purchase order is raised.
There is no cart on this page: the OPTIMASS 6400 is specified, not clicked. Give an engineer the process conditions and the symptom you are trying to solve, and the answer comes back as a configuration rather than a catalogue number.
Keep adjacent product options together for a faster catalog comparison.
OPTIWAVE 6300 delivers precise non-contact measurement for bulk solids. Rely on our expertise as a krohne radar level meter supplier and process instrumentation supplier.
View product
a bubble changes the mass and the damping inside the oscillating tube, so density and mass flow move at the same time and the drive can lose stability. entrained gas management keeps the meter operating through the entrainment, with operation maintained up to 100% entrained gas in liquids.
the sensor is described as having no crosstalk and as resistant to installation and process effects, with an optimised flow splitter for minimum pressure loss. in practice that means background vibration and flange stress have less influence on the measured value, though correct mounting and support still matter.
the device is sil 2/3 certified up to dn200 / 8″, and a partial proof test is possible with a proof test coverage of up to 82% using ptc. confirm the certified rating for your line size and configuration before the order.
accuracy is optionally ±0.05% of measured value, and the device carries the highest oiml accuracy class of 0.3 for custody transfer. on-site verification of the flowmeter is also possible with the opticheck service tool.
the published range runs from −200 °c to 400 °c / −328 °f to 752 °f, with pressure up to 200 barg / 2900 psig. product features and options depend on device configuration, so confirm the combination for your duty.
send the line data and the intended options to the supplier so the combination can be confirmed in one device. the manufacturer advises contacting them to check that the preferred functionality can be combined in a single configuration before the order is placed.
