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Continuos Duty Bilge Blowers
You can try an 12V automotive radiator fan mounted directly over the exhaust
vent. They last a long time, push alot of air, and are easy to replace. I seen one boat with multiple computer fans. 4 or more small fans mounted on a frame. If one fan dies, the rest keep going. Plus the fans cost $5 each at any electronics surplus store. Same princple applies to cheaply Air Conditioning a cabin. The computer fans are mounted on a square frame. 2 reusable home air conditioning filters act as dust catchers for the front and rear. A very small water fountain or bilge pump circulates cold sea or fresh water into a trickle copper tubing array. The fans simply blow warm air into the array, and out comes nice cool air... I can provide you a diagram if you like. You can alter the setup to suit your needs. Jim Rojas "Wayne.B" wrote in message ... On Mon, 24 May 2004 12:30:14 GMT, wrote: I don't run the blowers at cruise, as the venturi effect is sufficient to keep the bilge vented, but it's my "operating procedure," if you will, to operate them while the generator is running, before start-up of course, and while idling. ================================== Nothing wrong with that, good practices in my opinion. You just need to get a heavy duty blower, which as you have found out, does not apply to the plastic inline models. Another poster referred to the engines "drawing air out of the engine room". That does happen to some extent since the engines draw in air through the intake manifolds to support the cumbustion process. |
Continuos Duty Bilge Blowers
wrote in message link.net... Actually Bill, you are only half right here. The E/R blower does move the air out of the engine compartment, but that air must come from someplace. Whether the boat has a forced air intake or not isn't the question as the exhaust blower will cause a forced air intake just from the pressure of it operating. Remember, it can't take air out that does not exist, and it can't continually take air out if there is no supply. A continuous duty blower, in any engine compartment, works to ensure the compartment temperatures do not get too high... As we all know, too high of temperatures used when mixing a combustible fuel with the surrounding air for engine ingestion can cause the engine to vapor lock and therefore cease operation until such time as the engine compartment can be cooled for proper temperature mixing. "Calif Bill" wrote in message nk.net... Neither is your or Shen's. A E/R blower sucks the air out. Not blow air in. Therefore there should be at the most a slightly negative pressure. That Sucker fan, does not cause forced air into the bilge, is makes a negative pressure environment where the air from the intake line, trys to fill that negative area. If you had a blower in the intake, then there would be forced air. And the only time I force air in to my engine room is during the winter, as I install a solar powered Nicro vent over the intake to keep the humidity down, and dry out the rain water that wants to collect in the bilge. |
Continuos Duty Bilge Blowers
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Continuos Duty Bilge Blowers
On Tue, 25 May 2004 20:52:13 +1000, "K. Smith"
wrote: Thanks for the update & it seems maybe we're agreed; you don't really need the fan "continuously"? It's to purge the e/r prior to start & maybe can't hurt if at sustained low revs. I mention "continuous duty" because there are a lot of lengthy idle speed zones where I operate, so the blowers are used significantly more than I think the typical in-line blower is designed for. As such, after a single season of use, one or both is screeching. What I'm looking for is a higher quality blower that's specifically designed for continuous duty, as I believe it will last much longer than the typical Atwood blower....... |
Continuos Duty Bilge Blowers
"Terry Spragg" wrote in message .cable.rogers.com... Use the blower for safety before starting your explosion machine. After it starts, it will suck air much faster than any vent fan can. A 454 cubic inch engine running at 3000 RPM and wide open throttle would consume 394 cubic feet of air per minute. That is roughly what a standard 4" bilge blower will move. Turn it off. Do not pressurize the engine compartment, especially if you have a leaky exhaust. Leaky exhausts are bad no matter what. Most bilge blowers draw air out of the compartment, not force air in. A flame arrestor metal filter grille on an engine room exhaust vent driven by engine vacuum seems a good idea, needing only a vent into the engine combustion intake. What? You use a flame arrester to prevent a flame front in one area (generally a small enclosed space) from spreading outside to a larger area. Like the carburetor intake to the engine room. Where are you exhausting this engine room to that you are trying to protect? Plan on driving this boat through an explosive atmosphere? A sufficiently strong "Intake air leak" will evacuate any but the most catastophic exhaust leak into the engine compartment. I have no idea what you are trying to say here. Considering that the volume of exhaust gases is an order of magnitude greater than the amount of intake I don't see how you can make such a claim. Engine air intakes are noisy, and require a dust filter Never seen a dust filter on a boat. , so go a little further and build an intake muffler filter box. The air intake noise is nothing compared to the basic machinery noise of the engine. If noise is a problem, silence the entire engine room! Place any such vent as high as possible in the engine compartment, in case of flooding. Provide a watertigh closure for submerged running, if you are fitting a schnorkel. Dust filters? Submerged running? Are we talking about boats here, or off road vehicles? I have equipped vehicles so that they could wade across rivers and keep running, but it isn't easy. It is not nearly as hard if you have a diesel. On a gas engine you will have ignition problems long before you have water ingested by the carburetor. If you are talking about prolonged operation the starter and alternator will need a lot of attention as well. Use the leakage of air into the engine compartment as a cabin heat circulation function, for instance, by placing the hot water radiator in the bow. Fresh ventilation air could be drawn through a heat exchanger incorperated into the engine compartment ventilation / combustion air intake filter, to improve efficiency in the heating If you desire cabin heat, you will be much better off installing a heat exchanger with a circulation fan and recirculating the cabin air through the heat exchanger instead of constantly drawing fresh (cold) air into the cabin. It is generally unwise to have any air passages between the cabin and the engine compartment. The heat exchanger might accept cold water for air conditioning, which could be cooled by a keel radiator pipe. When it's 130 (F) out, sea water temperature air will be blessedly cool by comparison, and won't eat up much power. I have never been any place that was 130 (F). Where do you boat that gets that hot? Most of the places that I do freqent where it gets what I consider to be "hot" the water temperature, at least on the surface, gets to be 75 to 80 degrees. Some will say you should try to be safer with a tight engine box. Don't ever depend on a tight engine box alone for protection from fumes and fire. You certainly want to have isolation between the engine compartment and the cabin, but I have never heard of making the engine compartment itself air tight. Such a design certainly wouldn't be legal in the USA. Rod |
Continuos Duty Bilge Blowers
On Thu, 27 May 2004 22:57:45 GMT, WaIIy
wrote: On Thu, 27 May 2004 13:18:53 -0700, "Rod McInnis" wrote: A 454 cubic inch engine running at 3000 RPM and wide open throttle would consume 394 cubic feet of air per minute. That is roughly what a standard 4" bilge blower will move. You can't have it both ways, there is no "3000 RPM and wide open throttle". Depends how the boat is propped! 8) It wouldn't be ideal, but it's doable. |
Continuos Duty Bilge Blowers
"WaIIy" wrote in message ... On Thu, 27 May 2004 13:18:53 -0700, "Rod McInnis" wrote: You can't have it both ways, there is no "3000 RPM and wide open throttle". Why not? On my tow vehicle I end up at around 3000 RPM and WOT going up hills fairly often. Rod |
Continuos Duty Bilge Blowers
"WaIIy" wrote in message ... Get realistic here, we are talking about boats. Okay, why don't you get realistic? If you read back on the thread of discussion you may notice that there had been some discussion about the amount of air the engine was going to draw into the engine compartment. That is a relatively easy thing to calculate IF you assume that the engine is operating at a reasonable RPM (no significant restrictions in the intake) AND it isn't being throttled. An engine has a certain amount of displacement. If it is a four cycle engine (and isn't throttled) it will draw that much air every two revolutions. If the air flow into the engine is restricted then the calculation is much more difficult. However, if the bit of information you are interested in is the maximum air flow that you need to be concerned about then assuming WOT is a reasonable approach. As you throttle the engine the situation will only get better. The bottom line is that a typical engine running at typical RPMs will draw less air than a typical exhaust blower will. Rod |
Continuos Duty Bilge Blowers
"WaIIy" wrote in message ... Please list the boats that run a 454 at WOT and 3100 rpm. This is the claim you made that I asked you to address. You totally missed the point. The discussion wasn't about what RPM an engine would achieve at Wide Open Throttle, the discussion was about how much air the engine would draw into the engine room. If you want to nit-pick and draw things off topic I will counter that I never made any claim about 3100 RPM. You are the first one to mention that specific, exact RPM. If you want to be a bit more reasonable and talk about more general terms as a means of conveying information then I will point out that on many boats with planing hulls there will be a period of time that the boat may operate at WOT while the boat accelerates and climbs up on plane. The RPMs that the engine achieves during this period will be significantly below the maximum RPM it will eventually achieve. To drag this back into the context of the discussion thread: Terry Sprag said "After it starts, it will suck air much faster than any vent fan can." I submitted a calculation that shows that a fairly good sized engine, running at a fairly common RPM would NOT draw air "much faster" even at the worst operating, which is WOT. Closing the throttle will only strengthen my position. If you dispute the argument that I make then offer some reasonable counter argument, don't just throw needless flak out to confuse the issue. Rod |
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