Dual bent-tube Coriolis mass flowmeter

Paul Boughton

Yokogawa Electric Corporation's ROTAMASS LR is claimed to be the world´s smallest dual bent-tube Coriolis mass flowmeter.

The new ROTAMASS LR employs a dual bent-tube and self-draining design and represents a significant addition to Yokogawa´s ROTAMASS low flow line product family for gas and liquid flow measurement. It has been developed for use in research laboratories, being particularly suitable for chemical and pharmaceutical plants.

Designed to measure both liquids and gases, the effective turndown of the ROTAMASS LR is no less than 2000:1 for liquids and 5000:1 for gases, and the mass flow measurement range spans from 10.5 g/h up to 40 kg/h, achieving a measurement accuracy of ±0.15 per cent of reading for liquids and ±0.5 per cent for gases. Applications for this flowmeter include liquid and gas low flow measurement, high pressure gas pipelines, chemical injection, micro dosing systems, metering pump control, blending, precision and vacuum thin-film coating.

The ROTAMASS LR employs a dual bent tube that optimally decouples the core measuring element from process vibration that can cause fluctuating zero stability and reduced measurement accuracy. When fluid density changes, a single-tube Coriolis flowmeter can become imbalanced and start to behave like an emitter.

The ROTAMASS LR remains balanced because of the equal mass change in both tubes and the absence of interference from the process piping. By design, it is insensitive to fluctuations in the ambient temperature and achieves excellent zero stability under changing process conditions. The two tubes are made from C-22 alloy, which is less susceptible to thermal expansion than conventional stainless steel.

The measurement of tube temperature plays a key role in mass flow and density measurements. Normally it is more difficult to measure temperature with Coriolis flowmeters that have tubes with a smaller surface area. The ROTAMASS LR solves this problem by using an inline temperature sensor, ensuring exact and fast measurements in process temperatures ranging from 50°C to +150°, a unique feature in the low flow Coriolis flowmeter market.

The ROTAMASS LR sets a new safety standard in the low flow market, with a gas-tight, all-stainless-steel secondary containment that can handle pressures up to 65 bar. The ROTAMASS LR can be used in high pressure applications up to 400 bar. A huge variety of welded process connections are available. Unlike most flowmeters on the market today, gaskets are not used, minimising the risk of leaks.

For the prevention of fluid component separation and gas condensation, insulation and a heat jacket are available as an option.

For more information, visit www.yokogawa.com/uk

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