Greetings chaps.

Before I go off trying to re-invent the wheel, has anyone come up with a solution to sea spray being drawn into the engine room fan trunking and being delivered into the engine room via the fans. I have plenty of space inside the vent trunking before the fans to set up some type of screen/ labyrinth to get the moisture out of the air stream before the fans, any ideas?

Ian Mac.

Do you have any air filters fitted behind the louvers to the trunking?

After the air cleaners cut and fit several water traps. Air chisel a suitable point in a low down run of the trunking and cut and make up and fit new galvanise traps with a drain on each one. Seem to remember double welting on each join? Two U sections made up, one interlocking with the other to form an airtight joint, another knack jobby here. Haven't done it for donkeys years.

No filter material behind the louvers, at this point access to the inboard side of the louvers is a bit of an issue, about 2.4 m off the deck with the top of the louvered opening about 3.7 off the deck. Some sort of a platform will have to be constructed to access the louvered opening to maintain any type of filter. I am wondering what materials have been successfully used on the inboard side to stop the moisture being carried through with the air flow and robust enough to last over time. I'm thinking multiple layers of fine stainless mesh or some such.

Merlyn,
first thought when I came back this swing and seen the mess was to run a length of guttering along the edge of the trunking in the engine room where I have found water dripping out of the trunking all over #1 generator. Got some left over from my last home renovation project, but I'm wondering if I can deal with the moisture before it gets to the fans.

Never seen house guttering in the engineroom before, different to say the least, adds a whole new meaning to watercooled gensets. Wasn't the ships intake trunking ever designed properly from square one? Seems rather bizarre? Are the louvred deflector plates on deck long enough and the right angles to prevent water intakes? As prevention is better than cure maybe eyeball the intakes on deck with a view to modifying them ? Or work out what courses steered induce the most water intake and ban the skipper from using them? Weird.

I worked on a ship where the ventilation run over #1 SS with a Louver right over the exciter. The deck gang was hosing the superstructure and pointed the hose right at the intake with some rather spectacular results!

Where in relation to rest of the ducting is the water coming out, at the end of the line or somewhere close to the duct coming down from the fan?
Is there any water coming out anywhere else in that particular run of duct work?
Is this happening with all the engine room fans or just one fan in particular?
Are there any kind of old unused heating or cooling coil, fire suppression spray nozzles or spray nozzles used for humidity control in duct work somewhere that may be leaking water into the air stream?
Have there been any checks for leaking pipes above the duct that would cause water to run around or along the outside of the duct?
Have there been any checks for holes in either the deck head directly above the fan or air intake, in any drain scuppers from the upper deck that may pass close to the fan intake or where the duct work passes through an exposed area of the deck? On one ship I was on we had similar problems, one turned out to be a leaking deck scupper drain and the other was holes in the duct right under the fan where it passed through the deck. After the rust, scale, cargo and other crap on the deck that built up around the duct was removed it was found that the duct was almost completely rotted away.

Sounds like a breathe in job and off you go then. Hope the trunking has internal ladders properly fitted. I well remember my first trip inside trunking. Shell Tanker SS Theodoxos steam resuperheated ship, walking through the trunking and looking at the ladder on the inside of the funnel at daylight. Still remember it til this day. Spooky so best of luck with that one. Helps if you are built like the proverbial Japanese racing snake methinks.

I think you would have a trouble with fine mesh becoming blocked by dried salt. If there is enough space in the trunking perhaps a baffle to change the direction of air flow, water droplets would have more momentum and tend to keep going in the original direction where they could be caught and drained away, while the air would change direction easily. Something on the lines of a Cyclone separator.
All Navies have had tremendous problems with their Gas Turbines ingesting sea Water and turning into "Carrots". I believe their air intake systems are now as big as the Engine Rooms! They are probably the most knowledgeable people on this subject.

BP