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Guided Wave Radar is approved as a safety device

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Magnetrol’s second-generation Eclipse 705, two-wire Guided Wave Radar is type-approved to the newest European norms for steam drums, EN 12952-11 (water tube boilers) and EN 12953-9 (shell type boilers) as ‘primary safety’ and ‘secondary safety’ devices. These norms complete the PED construction guidelines with functional directives, typical for use on steam drums.

The Eclipse 705 has been type approved by the Dutch Stoomwezen, for use on steam drums as a secondary safety device, since 2002. As a secondary safety device, the Eclipse fulfils all general control functions on the steam drum, such as the controlling the hot feed water to the boiler. In its function of 'primary safety' device, the Eclipse operates as a safety switch and turns off the boiler in a safe way in case an emergency or dangerous situation occurs. The number of primary and secondary safety devices on a steam drum depends on the type of boiler, the manning of the boiler (permanently manned, semi-manned or not manned at all), its process pressure, capacity, etc.

Magnetrol’s Eclipse 705 combines two major advantages against the traditionally used transmitters: repeatability and an efficient process seal. The Eclipse uses Guided Wave Radar technology. This measuring principle measures independently of the process parameters such as density, conductivity, dielectrics, pH, etc. High pressure and temperature changes inside a boiler have an important impact on the accuracy and reliability of traditional transmitters such as differential pressure, displacer and RF capacitance. The process seal of the 7MS probe is specifically designed for use on saturated steam. The dynamics of the seal take the sudden and aggressive changes of process pressure and temperature into account.

Non-steam applications

The Eclipse 705 with 7MS probe resists a process pressure of 155bar at an equivalent temperature of +345degC in saturated steam applications. For non-steam applications, the Eclipse can be used on process conditions from -196degC up to +430degC/full vacuum up to 430bar. The Eclipse 705 transmitter can be configured for both measuring level and liquid–liquid interfaces in level units or volume units.

Also available is the Eclipse 705 with a SIL 2 version. The additional diagnostic tools allow users to integrate this transmitter within highly demanding safety instrument loops. With a SFF (Safe Failure Fraction) of 91 per cent, the Eclipse is claimed to be the only TDR transmitter on the market that scores this highly on safety level. The Eclipse 705 (with enhanced SIL electronics) is suitable for SIL 2 loops as a 1oo1 device (hardware fault tolerance 0 – FMEDA analyzed by Exida per IEC 61508).

A free copy of the FMEDA/WIB test report can be downloaded from www.eclipse.magnetrol.com.

20 January 2009

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