Clamp-on ultrasonic flowmeters offer a convenient method for measuring flow without the need to interrupt
processes.
Overview
The technology has a number of general advantages such as no pressure loss, non-invasiveness and low maintenance; clamp-on flowmeters are also easy to fit at low capital costs.
However, experience has shown that achieving an accurate and reliable flow measurement with clamp-on technology can be troublesome. This is due to the fact that measurement is very much influenced by the accuracy of input by users of the pipe and liquid characteristics. Inaccuracies result in flow measurements with lower reliability and less accuracy. The performance of a clamp-on flowmeter can decrease drastically on pipes with different liner materials, and is also affected by flow conditions, temperature change and upstream disturbances.
In practice there are uncertainties in many of these parameters, which lead to erroneous measurement results without operators even being aware of what is happening. Little surprise then that traditionally, in cases where accurate flow measurement was required, inline flowmetering became the method of choice.
Developments
Krohne has made substantial technology enhancements in order to improve the performance and extend the range of applications for ultrasonic flowmeters. One of the beneficiaries has been the 3-beam inline ultrasonic flowmeter, which makes flow measurement independent of even the liquid flow profile. According to the company, accuracies for this type of instrument are the best that can be found worldwide and applicability is universal.
To improve the performance of clamp-on flowmeters, Krohne developed the Optisonic 6300 meter for optimised reliability. An innovative new electronics concept provides an integral quality indicator that allows measurement uncertainty to be minimised. While adjusting the position of the transducer a bar- graph gives users a visual indication of realtime signal quality; this allows easy optimisation through maximisation.
An evolution that has been evident in the process industry for a number of years is the demand for user-friendly equipment; the key phrase is ‘ease of use at all stages’. In the case of clamp-on flowmeters this applies to both the electronic and mechanical components. Krohne has addressed these through an intuitive HMI and a high level of industrial robustness in the frame construction.
Optisonic 6300
The engineered design of the OPTISONIC 6300 sensors ensures the clamp-on resists even harsh operational conditions. The sensor and converter are weatherproof and all transducers are intrinsically safe in order that the clamp-on is suitable for use in hazardous environments. Transfer of acoustic signals is via industrial coaxial cable and gold plated connectors. The casing has multiple advantages, not only as protection but also as a solution to reduce maintenance. The cover design ensures that the coupling grease between the transducers and the pipe is unaffected by external factors allowing long intervals between services. When re-greasing is required the casing facilitates access to the transducer surfaces thus eliminating any troublesome repositioning after maintenance.
Flexible system configuration
A selection of three different sensor types can be made to cover a complete pipe diameter range from DN15 to DN4000. Additionally, two different types of sensors are available for applications with extended temperatures from -50 to +200°C. The same sensor type can be applied for any piping material, with or without liner, and wall thicknesses of up to 75 mm. Multiple sensors can be combined with one electronic signal converter to enable differential flowmetering.
Time equates to money in the process industry and clamp-on flow-metering is an attractive option, however, the choice of meter requires consideration.
As far as the process goes there should be zero downtime and the meter should be easily configurable and operational immediately. As far as installation goes sensor mounting should be straightforward without the need for any special tools. To achieve this Krohne designed the Optisonic sensors for single handed mounting, which together with the intuitive set-up wizard in the electronics allows installation in less than 15 minutes. Flow measurement can be done anywhere and start-up is immediate.
The new OPTISONIC 6300 clamp-on flowmeter with its robust industrial construction and re-greasing concept provides a revolutionary solution in easy handling.
For more information contact Mahendra Rajcoomar, Krohne South Africa, +27 (0)11 314 1391, [email protected], www.krohne com
| Tel: | +27 11 314 1391 |
| Fax: | +27 11 314 1681 |
| Email: | [email protected] |
| www: | www.za.krohne.com |
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