Rick Nothing about that sounds like a geek to me, just some very good information based on sound knowledge, especially this part:
Lots of smell – which may make a blower to ventilate the engine spaces very desirable Dwight Veinot C&C 35 MKII, *Alianna* Head of St. Margaret's Bay, NS [email protected] On Tue, Dec 29, 2015 at 1:56 PM, Rick Brass via CnC-List < [email protected]> wrote: > The geek in me just has to jump in here with some technical information. > So here goes: > > > > Yes, Rick, vaporized diesel will blow up like vaporized gasoline. > > > > And Yes, Patrick, diesel does not vaporize easily. And is a lot less > likely to support a flame than Gasoline as well. > > > > The flash point (lowest temperature at which a liquid starts to evaporate) > of Gasoline is -45 to -50 degrees F (-60 C, I think). The flash point of #2 > diesel is 126 F (52 C). Biodiesel, BTW, is about 225 F so if you use B10 or > B15 in your boat the flash point of the fuel would be higher. > > > > The ignition concentration of a fuel vapor is the percent of fuel vs air > that will support ignition. Too low a concentration or too high a > concentration and you get no fire. That is why (if you are very lucky and > not too bright, you can throw a lit match into a bowl of gasoline and > nothing happens. For gasoline the range is 1.4% to 7.6%. Diesel is pretty > similar at 0.6% to 7.5%. > > > > The ignition point (temperature at which it will start burning) of gas and > diesel are also very similar. Gas is 475 F, and diesel is 494 F. > > > > But gasoline is much more volatile, and at much lower temperatures. So you > are likely to find gasoline vapor vs. diesel vapor. Any fuel leak at above > -45 F will result in gasoline vapor. A diesel leak will just make a puddle > unless the temperature is above 126 F. Yes, it would be a smelly puddle, > but your nose can sense vapor concentrations far below the concentration > that would support ignition. > > > > Since the density of the gasoline vapor is about 2.0 (air is by definition > 1.0) at standard temperature and pressure (70 F and sea level), the > combustible vapor sinks to the bottom of your bilge. Diesel vapor would do > the same thing, except a measurable concentration of diesel vapor could not > exist at STP. Even high pressure diesel forced out of a pinhole leak in one > of your injector lines is more likely to result in a smelly mist (too high > a concentration to support ignition) than in a combustible fuel vapor. > > > > The flash point indicates when a liquid starts to evaporate. But there is > another specification called the fire point that is probably a better > illustration of the relative risk from gasoline vs. diesel. The fire point > is the temperature at which a liquid fuel will generate a vapor > concentration high enough to support a flame for 5 seconds – which is > enough time to cause significant evaporation of the liquid and start a > real fire (as opposed to a momentary flash). Liquid gasoline has a fire > point of 30 F (-1 C), while liquid diesel is 154 F (68 C). > > > > So unless you are boating in some really ridiculous heat, you are unlikely > to get a fire from diesel fuel. Lots of smell – which may make a blower to > ventilate the engine spaces very desirable – but a fire is not a high > probablility event. > > > > Rick Brass > > Washington, NC > > > > > > > > > > *From:* CnC-List [mailto:[email protected]] *On Behalf Of *Patrick > Davin via CnC-List > *Sent:* Monday, December 28, 2015 10:43 AM > *To:* [email protected] > *Cc:* Patrick Davin <[email protected]> > *Subject:* Re: Stus-List Proper Blower Installation - 30 mki > > > > Diesel doesn't vaporize easily, unlike gasoline. That's one of its big > advantages on boats, that it's non-volatile. It's good practice to shut > down the engine at the fuel dock anyway, but they're probably asking that > more as a general policy due to the gasoline boats they fill (or in case > some gasoline vapors wafted over to your boat). > > > > The flash point (vaporization temp) of diesel is 126 F: > > https://en.wikipedia.org/wiki/Flash_point#Examples > > > > There's a good writeup on engine blowers here: > http://www.unitedmarine.net/blog/index.php/2013/01/30/who-needs-engine-room-blowers/ > > > > On Mon, Dec 28, 2015 at 6:09 AM, <[email protected]> wrote: > > ---------- Forwarded message ---------- > From: Rick Rohwer <[email protected]> > To: [email protected] > Cc: > Date: Sun, 27 Dec 2015 22:16:22 -0800 > Subject: Re: Stus-List Proper Blower Installation - 30 mki > > I am pretty sure vaporized diesel will blow up like gasoline vapor. I > know vaporized cooking fat will. Don’t most of the fuel docks ask you to > shut down the engine and run the fan while fueling? > > > > I had never thought of it as an air supply for the engine. > > > > Rick > > Paikea 37+ > > Poulsbo, WA > > > > _______________________________________________ > > Email address: > [email protected] > To change your list preferences, including unsubscribing -- go to the > bottom of page at: > http://cnc-list.com/mailman/listinfo/cnc-list_cnc-list.com > > >
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