ER Vent fan placement

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CMChiefEng
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ER Vent fan placement

Post by CMChiefEng »

Greetings Great Minds!

I am in the process of repowering a couple fleet vessels and find that I may have to install new vent fans in the engine rooms. The original vent fans were hydraulic drive and were removed 15 years ago but replaced with 24v squirrel cage exhaust fans. If I am to replace these with larger ones, I will go 120v but I'm curious about what you all think is the better placement? There is a vent trunk at deckhead level near the transom and another at the fwd ER bulkhead but it's a vertical trunk to the flybridge level.

Opinions on which trunk to install a fan? Forced air in the deck level trunk or exhaust in the vertical trunk?


Thanks in advance! Calm Seas everyone.
Philip Mollet
3rd Class Motor
Currently Engineering a desk in an office with no windows (throwback to an ECR perhaps?)
popeye62
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Re: ER Vent fan placement

Post by popeye62 »

Hello Philip, you didn't say what size of vessel but I think she is small? I would follow the original design which was probably one supply fan and one exhaust. The fans are sized to the space, but more importantly the size of the engine, and how much air it sucks up (you can make a simple manometer with a piece of clear tube). The air pressure in the ER should be the same when alongside and at full whack (If you know big ships then you know that when the main engine is stopped you have to either use two-speed fans or shut them down to avoid big pressure differences in the ER when, depending on which way the doors open, you either can't get out of the ER or the door rips your arm off when un-latched). Re. the position, I would go for the supply forward and the exhaust aft. If the forward is high up and no chance of sea water ingress it might give you a 'ram air' effect but probably depends on the height of the vertical and the csa of the trunking. Another thing to consider is fire; you must be able to shut the space down especially if the ER protected by CO2 but even just to starve a fire of O2. Exhausting over the back end to clear the space would be safer(?) If you are not required to comply with SOLAS they are still good rules to follow. Good luck, John
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