SEM-SAFE® low-pressure CO2 system System description The system used on board CMA CGM Benjamin Franklin is a low-pressure CO2 system containing 27.8 tons of liquid CO2, which is kept at a temperature of -18°C and a pressure of 20 bar by the 2 completely independent cooling units. (According to IMO SOLAS, the cooling system must be fully redundant). Due to the high quality in design and manufacturing, these units run only an average of three hours per day. Furthermore the special insulation of the tank will maintain a stable temperature for approx. 48 hours without cooling. As the first company in the world, Danfoss overcame the technical challenges involved with designing a low-pressure CO2 system complying with class requirements to supply 85% of the calculated CO2 concentration within 2 minutes for engine rooms of this size (38,000 m³). Danfoss designed the system with three diptubes compared to the standard one. This posed another issue – what will happen to the internal pressure in the tank if three large valves were to be opened at the same time. Based on the many years’ of experience of working with low-pressure CO2 fire fighting, Danfoss found the solution in the form of the N2 booster unit, which was developed in cooperation with Force Institute. As the keel laying of CMA CGM Benjamin Franklin was done after July 1, 2014, it was necessary to take MSC 339 (91) into consideration. The main challenges in this resolution is the time limit for release to cargo holds and the fact that it must be possible to make 1/3, 2/3 and full release based on the degree of filling in cargo hold. Taking security measures seriously and in order to live up to the time limit for release, Danfoss designed the system with larger distribution pipes, and therefore it was no longer possible to use the same pipes for smoke detection and release of CO2. CMA CGM had a desire to keep all release functions at the same location to avoid any excessive risks for the crew. As Danfoss values crew safety above all, a solution was found to design the system, with separate lines to all cargo holds, which results in a rather large manifold encompassing 12 distribution valves. To simplify installation work, Danfoss included all these features on the same single frame, This greatly reduces any risk of making mistakes, as all components are pre-installed/wired and tested in the Danfoss workshop prior to shipment. The high quality single skid mounted SEM-SAFE® low-pressure CO2 system from Danfoss. ® Danfoss Fire Safety A/S · Middelfartvej 9 · DK-5000 Odense · Denmark Tel. +45 7488 7800 · E-mail firesafety@danfoss.com · www.semsafe.danfoss.com Danfoss Fire Safety A/S can accept no responsibility for possible errors in catalogues, brochures and other printed material. Danfoss Fire Safety A/S reserves the right to alter its products without notice. This also applies to products already on order provided that such alternations can be made without subsequential changes being necessary in specification already agreed. All trademarks in this material area property of the respective companies. SEM-SAFE® logotype is trademark of Danfoss Fire Safety A/S. Danfoss logo type is trademark of Danfoss A/S. All rights reserved. © Copyright Danfoss Fire Safety A/S | 2019.07
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