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Go Back   SailNet Community > General Interest > General Discussion (sailing related) > Propane leak into the bilge. What to do?
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Topic Review (Newest First)
04-08-2013 10:18 AM
svHyLyte
Re: Propane leak into the bilge. What to do?

Quote:
Originally Posted by MedSailor View Post
Ideally, I like to think of disasters and make plans for how to cope with them, before they happen. Sadly, this is not always the case, but when it has been, is sure is nice to have a plan (or plans) of action to try. That said, there is no propane leak on my boat right now. But what if there was?

We all know propane + enclosed boat hull = bad. We can buy sniffers to alert us to the presence of propane, but what if we did blow a seal and we leaked a bunch of the explosive stuff into the bilge. How do we get it out?

I've heard that a manual diaphragm bilge pump can be used, but I'm a bit skeptical. What about an electric (ignition protected of course) bilge pump? I may have to pick up a colored smoke bomb this 4th of July and see if I can figure out how to get rid of all the colored smoke to test any theories we come up with.

MedSailor
If you were convinced the bilge was fully laden with Propane one could simply use one's dinghy foot pump with a length of tubing to the lowest part of the bilge and another up through the companionway and over the side. One could adapt garden hose for this if necessary. Since there will be no resistance to the pump it would be relatively easy to cycle and one will collect roughly 1/3rd of a cubic foot of air per cycle with a typical foot pump. It might take quite a few cycles, but it would certainly mover the air/propane.
04-08-2013 12:47 AM
n8kraft
Re: Propane leak into the bilge. What to do?

I like all the previous posts, but my own holds the highest position in my own heart, but I'm sure we can all agree that the best remedy would be to open the hatches and GO SAILING (without risk of rogue waves while crossing an ocean swaming the boat to an early grave) and use that methodology to allow adequate air flow through the boat.
04-06-2013 03:59 PM
smurphny
Re: Propane leak into the bilge. What to do?

Alcohol certainly can flare up. I've had it happen but once you get used to handling it and using the stove, it is not a big issue. Alcohol, of course, is soluble and therefore can be extinguished easily with water, unlike any of the other fuels. I guess the point is that if you get a flare-up you are there and can easily control anything that may happen. As far as being invisible, well...ya. You figure that out fairly easily. Alcohol is not likely to explode like propane unless you pour a couple of gallons into the bilge. That said, replacing my Kenyon with a kero stove is on the list. I actually bought one of those pressurized kero stoves a couple of months ago Butterfly 2412 Brass Pressure Stove to experiment around with and design some sort of s.s. enclosure for two of them. The only thing I don't like about it is the kero smell. It will actually run on diesel but makes a lot of carbon.

One other thing is that spackle buckets make good storage containers for spare alcohol cans. Even if a leak were to occur, it would be contained. The steel cans alcohol comes in are not the best on a boat. If stored with bubble wrap so they can't bounce around, they're pretty secure and stowable.
04-06-2013 03:39 PM
travlineasy
Re: Propane leak into the bilge. What to do?

Thought this may shed some light on this subject:

BOAT EXPLOSIONS

Boating is an enjoyable pass time for many Canadians. Unfortunately, the dangers associated with this activity are often misunderstood or ignored.

Marine craft present a particular hazard to fire and explosions. According to US Coast Guard statistics, fires and explosions account for the largest single cause of marine property damage. The hazards exist owing to the presence of flammable liquids present within confined, poorly ventilated spaces. Gasoline fuel, which is used to propel the majority of private marine craft presents the most common hazard. Gasoline can be released into boat compartments as a result of equipment failure, spills and improper storage of fuel supply.

Gasoline has a lower explosive limit (LEL) of 1.4% by volume and an upper explosive limit (UEL) of 7.6%. The percentages within the LEL and UEL represent flammable gasoline/air mixtures. Therefore, a flammable gasoline/air mixture can exist when 100 ml (approx. 200 drops) of gasoline liquid is vaporized in 1 cubic metre (approx. 35 cubic feet) of confined air space. Furthermore, gasoline vapour is heavier than air and tends to collect in lower compartments of the boat. Therefore, a small leak or spill can present a significant hazard of explosion and fire.

Diesel fuel presents a reduced explosion hazard owing to its higher flash point which prevents it from readily evaporating to produce a flammable mixture. The LEL for No. 1 grade diesel fuel is 3.5% by volume and the UEL is 6.9%. The LEL is higher and the range is smaller, further reducing the hazard. However, higher temperatures will cause diesel fuel to evaporate more readily resulting in explosive mixtures being present within confined air spaces on marine craft. Temperatures within cabins and engine compartments may be significantly raised by the hot summer sun, increasing this hazard.

In addition to engine fuels, galley stoves, which operate with fuels such as alcohol, kerosene, and propane present significant fire and explosion hazards from improper operation, improper installation, fuel leaks and spills. Propane (LEL = 2.5%, UEL = 4.5%) presents the greatest explosion hazard.

Since it is heavier than air, a propane leak can create and explosive mixture in lower boat compartments. Alcohol can also create explosive mixtures and can cause accidental ignition of combustibles owing to its clear, colourless flame. Therefore, great care should be exercised when using these fuels. Furthermore they should be stored outside or in ventilated compartments sealed from the main cabins and other compartments.

Marine construction materials add to the fire hazard. Fiberglass and wood are the two most popular construction materials used for pleasure craft and small commercial boats. Both of these materials are flammable, increasing the probability of complete destruction of the boat when a fire occurs. This increases coverage concerns.

Preventative measures include proper ventilation, proper refuelling methods, avoiding spillage and overflow, periodic inspection of fuel systems, use of inflammable materials of construction, and installation of fire suppression equipment. Electrical systems should also be properly designed and maintained to reduce electrical ignition sources. Bonding ground systems are preferred for all boats with fixed electrical systems. Fire extinguishing equipment is required by law and can serve to prevent the spread of fire, reducing damage. In addition, exhaust blowers should be running prior to operation of engines.

Refuelling also presents other significant fire and explosion hazards. Fuelling should take place under good lighting conditions and smoking and open flames must be forbidden in the nearby area. Furthermore all electrical and power equipment should be closed and the possibility of static discharge from the fuelling nozzle to the filling port must be eliminated by maintaining continuous contact while fuelling. In addition, all unnecessary personnel should stand clear of the area.

Since the bilge is located at the lowest point in a marine vessel, it represents another area of concern. Released liquid and vapour fuels are heavier than air, and therefore, will flow to this location increasing this hazard. This can result in flammable mixtures being present within the bilge. Frequent flushing and cleaning of the bilge area and good ventilation will reduce this hazard.

Some boaters elect to live on their vessel year round. As a result, heaters are required to provide a comfortable environment. Electrical heaters introduce a possible ignition source for flammable mixtures, not to mention the usual fire hazards associated with this type of equipment. Propane and other LPG heaters are found on some boats. However, most insurance companies will not underwrite marine vessels equipped with appliances with pilot lights as this provides an ignition source for flammable mixtures. This type of equipment should be avoided.

The above information came from http://www.waltersforensic.com/artic...n/vol3-no2.htm

From my own, personal, first-hand experience, I've seen dozens of alcohol fires in galleys. These were fires that got pretty wild in some instances, and could have been catastrophic had the boat's operator not quicky acted with a fire extinguisher. Just filling an alcohol stove underway, even in relatively mild conditions, can result in spills.

I've been using propane for 8 years, a 20-pound tank that is mounted in a special compartment. Never encountered a single problem. I do, however, have a sniffer that can detect a myriad of explosive gasses, including propane, gasoline, diesel, carbon monoxide, etc...

Yesterday I got a call from the marina saying an alarm was going off inside the boat. I told them to not allow anyone near the boat, and quickly drove to the boat to check it out. When I arrived the alarm was not sounding. I opened the outside hatches, stuck my head inside and detected a very slight gasoline odor. I filled the tank the day before, a time when the temperature was in the lower 30s. Yesterday afternoon the temperature rose to the 50s and the sun was beating down on the boat. Apparently, the rise in temperature was just enough to cause the gasoline to expand a bit and a small volume was forced out the tank vent. That tiny amount, which I don't believe was sufficient to prove dangerous, allowed a small volume of vapor to seep into the cabin, thereby triggering the alarm.

I decided to check the alarm and determine just how little gasoline it would take to trip the alarm. As it turned out a single drop of gasoline on a small piece of paper towel and placed six inches from the detector was all it took. WOW! That thing is really sensitive. I also tested it for propane by pressing down on the trigger of a propane light which I use for lighting the stove. I held it down for less than a second and the alarm triggered. This, despite the fact that the lighter was at least 6 inches away and puts out only a tiny amount of propane.

Explosive gas sniffers vary significant in price, depending upon whethe or not it has the word "Marine" associated with the product. The one I purchased came from Amazon.com, it was designed for boats and RVs, and the price was under $40. You can find higher priced models that have selinoid cut-off valves that close automatically with the detection of the slightest amount of explosive gasses present.

The alarms themselves are extremely loud, loud enough so that the person who called me heard the alarm from his condo's third-floor balcony. I seriously doubt that anyone could be aboard the boat and NOT hear the alarm sounding.

Good Luck,

Gary
04-06-2013 12:29 PM
smurphny
Re: Propane leak into the bilge. What to do?

The best way to avoid a propane leak is to NOT use propane for regular cooking. Having a tank above decks just for a grill is probably safe enough but I would not have 20# of propane on a boat piped to a stove below deck..period. Just my opinion but I think the danger on a boat is simply too high for the convenience of quickly turning on a burner to cook. The less convenient alternatives of alcohol, kerosene, or diesel are infinitely safer on a boat. I keep a couple of small propane canisters for a little gimballed stove and soldering torch and even take care with them so that if they leak, they will vent and cannot settle in the bilge.

I still have a Kenyon pressurized alcohol stove which works just fine. If I replace it, it will be with a non-pressurized alcohol or a kerosene stove.
04-06-2013 11:42 AM
paul323
Re: Propane leak into the bilge. What to do?

Er - dumb question - my propane tanks are in their own compartments, with a hinged lid for access, and a drain hold on the bottom leading to the outside of the boat. The solenoid and tubing is at the top, and the caulked in so it can't leak gas. Isn't that the best way to set them up?

I wouldn't want a loose propane tank inside my boat. I've seen tanks in various locations. but they are always in their own boxes and "drain" externally to the cabin.
04-06-2013 11:17 AM
pdqaltair
Re: Propane leak into the bilge. What to do?

Quote:
Originally Posted by travlineasy View Post
For the future, get a sniffer with a solenoid valve that automatically shuts off the gas if the slightest concentration of propane, and other explosive gasses, is detected. They can be found for under $200 at most marine stores, and in some RV stores, under $100.

Gary
And test the system each spring. Simply wave a propane torch or similar (butane lighter works) near the detector an confirm it cuts the gas and alarms. Takes only moments. Depending on dampness, the element has a finite life. One more reason to keep a dry boat.

It is also the season to change those CO and smoke alarm batteries!

--------

Being in the industry and having done gas explosion accident investigations, I know what I would do; close the gas bottle (should be accessible in a locker on deck, open a few hatches I could reach from on deck, and immediately leave, if only to sit in the dingy for 30 minutes (much longer if at dock and I can go get lunch!). Bad weather at sea? I would hope you noticed sooner, but a broken line is possible. Turn off the bottle, open every hatch, and not touch any switches. If the gas is not yet strong in the cabin I might turn off the main. I would wait some time and then ventilate the bilge by gently removing covers. Even in a marine environment some boat cabins build static, so I would ground my hands before reaching for the boards; I've seen some nasty static triggered explosions.

--------

Any actions (other than closing the bottle and opening a few hatches) carry some ignition or exposure risk. Better do little and wait for dispersion.
04-06-2013 09:06 AM
smurphny
Re: Propane leak into the bilge. What to do?

Quote:
Originally Posted by Hartley18 View Post
Smurphny, to answer your questions:

1. Yes, a "spark protected" device good for gasoline vapour will also be fine for propane.

2. Commercial Propane is mix of gases (mostly Propane, Propene, Butane and a bit of Ethyl Mercaptan) and, being not all that much heavier than air, will mix with pretty much everything around including lots of oxygen inside a small, rocking, boat and then go off nicely with a little spark.

3. You REALLY don't want to let off either CO2 or Halon extingushers on a small boat and I actually thought it was illegal in many countries to have them on board. Reason being, you might put out a potential fire - but you'll asphxiate yourself first.



It's already been pointed out that a diesel engine will run happily on propane up the air intake - often to destruction, since there is no (safe) way to shut down the engine. I guess that would make using the engine a BAD way to keep any gases at bay..


The best, most practical, most normal, most-used-everywhere option is, as mentioned earlier, is to turn off all electrical devices and ventilate the boat.
The main concern is certainly getting the gas out of the bilge and dissipated into the air. The dilemma is that in this situation it is difficult to know what sequence of events would be safest. If there is wind blowing and you can open up, it seems it should be possible in a reasonable amount of time to blow it out. I have never had the contents of a 20# bottle of propane settled in the bilge so can't really say how difficult dissipating it might be. My thought was that in this situation, immediately prohibiting combustion would be a better way than to screw around with a certain bomb-in-the-bilge. We all have seen the results of propane ignition. Quickly eliminating any possibility of this happening would make sense to me, rather than hoping to avoid generating a spark while fiddling around trying to turn off switches. Refrigeration, bilge pumps, computers, radios, etc, could all supply ignition. Many laminate workers have discovered the hard way how refrigerators can ignite contact cement fumes.

CO2 IS dangerous as far as asphyxiation but if used with that knowledge might stop any potential explosion. Not being a chemist, I don't know if it would possibly just sit on top of the propane (which would not solve the problem), settle under the propane (forcing it up and out), or mix with it chemically. We need a chemist or someone in the industry to chime in on that. Same for Halon. Hand-held CO2 extinguishers are still available and, yes Hello, those Halon units are wicked expensive.
04-04-2013 12:15 AM
Classic30
Re: Propane leak into the bilge. What to do?

Quote:
Originally Posted by smurphny View Post
That's good info. BubbleheadMd. The questions that need to be answered are whether or not "spark protected" devices that were designed for gasoline vapor are good for propane as well. I also wonder whether CO2 or Halon would be displaced, diluted, or mixed with a bilge full of concentrated propane. Propane and CO2 molecules are very close in molecular weight, so who would displace whom? Most of the info. on fire suppression substances is based on after-the-fire-starts scenarios. The issue of intervening to eliminate an explosion before it can occur is not usually discussed and is a good topic to explore.
Smurphny, to answer your questions:

1. Yes, a "spark protected" device good for gasoline vapour will also be fine for propane.

2. Commercial Propane is mix of gases (mostly Propane, Propene, Butane and a bit of Ethyl Mercaptan) and, being not all that much heavier than air, will mix with pretty much everything around including lots of oxygen inside a small, rocking, boat and then go off nicely with a little spark.

3. You REALLY don't want to let off either CO2 or Halon extingushers on a small boat and I actually thought it was illegal in many countries to have them on board. Reason being, you might put out a potential fire - but you'll asphxiate yourself first.

Quote:
Originally Posted by Barquito View Post
That is impressive and eye opening. I suppose a running engine would tend to keep any gasses at bay in the area of the engine b/c it is always drawing in fresh air.
It's already been pointed out that a diesel engine will run happily on propane up the air intake - often to destruction, since there is no (safe) way to shut down the engine. I guess that would make using the engine a BAD way to keep any gases at bay..


The best, most practical, most normal, most-used-everywhere option is, as mentioned earlier, is to turn off all electrical devices and ventilate the boat.
04-03-2013 09:22 PM
Brewgyver
Re: Propane leak into the bilge. What to do?

Air (roughly 78% Nitrogen, 21% Oxygen), propane, CO2, and Halon (or the ozone-safe replacement gas) are all miscible at atmospheric pressure. So, while adding CO2 or Halon would reduce the LEC (lower explosion level) fastest, simply adding air will do the same thing. Using an ignition protected blower is simple and safe, and many boats already have them in place. That's what I would do.
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