engine room pressure/vaccuum
engine room pressure/vaccuum
(OP)
In thread321-181668: Engineroom Fan someone commented that they believed an engine room should be slightly pressurized.
I wondered everyones consensous is.
I've always believed engine rooms shoulg be slightly below 1 atm because a pressure differential greater then 1 ATM would:
raise engine room temps slightly
allow a denser media for airborn noise trasmit through
pump anything leaking, burning off etc into adjacent compartments when ever a door is open or otherwise less then air tight.
I wondered everyones consensous is.
I've always believed engine rooms shoulg be slightly below 1 atm because a pressure differential greater then 1 ATM would:
raise engine room temps slightly
allow a denser media for airborn noise trasmit through
pump anything leaking, burning off etc into adjacent compartments when ever a door is open or otherwise less then air tight.





RE: engine room pressure/vaccuum
The reason I believe the engine room should be slightly pressurized is for correct engine operation. In my opinion many engine power loss problems come from a lack of air available for combustion, it surprises many people how much air is actually needed for correct combustion and it is easy to starve engines of air in tight engine rooms. Ideally I think the engine room should be neutral at all engine revs. But that would be difficult that’s why I aim for slightly more at cruising.
I remember one boat I worked on I could feel resistance when opening the door when the yacht was cruising and you could hear the engine note change as soon as the door or hatch was opened. Another fan remedied the power loss problems it was having.
As for your reasons on lower pressure, I think proper engine operation is more important, also you can approach those issues separately.
High temp? You have other problems. Lack of air for the engines would more likely cause high temp.
Noise? Insulate more.
Fumes? Shouldn’t be any, apart from the air being changed frequently nothing should be burning for any length of time or leaking.
But this is just my opinion I would be interested in hearing others.
RE: engine room pressure/vaccuum
One of the HVAC balance issues pertains to accommodating opening and closing doors; and to select the zones where to close dampers upon fire or smoke detected. Closing HVAC dampers and stopping the intake and exhaust fans greatly affects the room air pressure differences.
RE: engine room pressure/vaccuum
RE: engine room pressure/vaccuum
CAT, Cummins, MTU, Mak, and just about all the others I know of publish guidelines for engine room ventilation, almost all universally ignored by builders and installers in my experience.
In general full load intake air restriction (with clean filter/silencer) should be less than 5" H2O, compared to atmospheric pressure. Best practises I have seen try to limit ventilation air temp rise across engine space to less than 10 degrees F, and try to keep air temperature to air inlet within 5 degrees F of outside air temp at full rated load.
Hope that helps
RE: engine room pressure/vaccuum
I saw engine room hatches on a large yacht,(60ft Hatteras), that were sucked out of hands to slam shut. (Terrifyingly!) You could hear the two 8V53's change note simultaneously.
It can be pretty tough to get enough air into an engine room when breaking waves and a lot of water surround the problem.
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: engine room pressure/vaccuum
Most ships take combustion air from the space.
I have 4 ea 11mW diesel generators. We were originally going to use some sort of logic or VFD to control fans as generators started and stopped. We didn't and I was worried. Turned out the space and supply ducts were large enough that there was no issue. The door closers worked in all combinations, but are trickiest to set with all 4 engines running at full load, which I can't simulate in port.
RE: engine room pressure/vaccuum
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: engine room pressure/vaccuum
OK, OK. MW.
RE: engine room pressure/vaccuum
A diesel engine burns 14 times as much air as fuel. You can never get enough air into an engine room.
Offshore Engineering&Design
RE: engine room pressure/vaccuum
The more air the better, the density of the air having an effect on heat of the engine room is a minor player.
RE: engine room pressure/vaccuum
RE: engine room pressure/vaccuum