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Old 13-08-2006, 21:27   #16
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Densities

Air @ 59º F =1.29274 kg/cu. meter

LPG Liquid = .5077 kg/liter

LPG Gas = 1.83 kg/cu. meter

Which makes air 2/3rds the weight of propane.

If moved around by an air ventilation system it will eventually dissipate but the more oxygen present the more dangerous it becomes. Pumping it out would be the safest way to get it out. A bellows or diaphragm pump system would be the safest way to move the gas in an open environment. A bilge blower would help but God forbid it blows past the fan motor. Sealed brushless motors are the only motors used in flammable gas systems. I would not buy a bilge blower that was not to specs.

Propane is very popular due to its storage ability and burn ratio (78%) Another reason to go propane over CNG is .839 Btu's-natural gas: 1.97 Btu's for propane, # for #.

Moving the air around would work but it would take a windstorm to move it fast enough to suit me.

The best advice is the spray bottle with dish soap and a gas detector. Just don't let it happen.
If you leave the boat at a dock, make sure the gas is off or just take the LPG bottle(s) with, in the back of a pick up truck preferably. There is always some risk in handling flammables, just use you head. It only takes one idiot with one match to burn down a whole forest. Maintenance and inspections are the key words......................._/)
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Old 14-08-2006, 03:53   #17
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Basic Propane Safety:
If you smell propane, no matter how strong or weak the smell, treat it as a serious gas leak. There are four ways to test for a gas leak: the sniff test, the pressure test, the bubble test, and propane gas detectors.

Sniff Test:
Being heavier than air, leaking propane tends to collect initially in low areas. To check whether there is a leak using the sniff test, get down on your hands and knees and sniff close to the sole, and/or bilges to smell for propane. Propane smells somewhat like rotten cabbage.
Be aware that under rare conditions, propane’s distinctive smell can "fade" or diminish in intensity - hence, a leak can exist and the gas may not have a detectable odor.

Propane is naturally odourless, but an artificial odourant (usually ethylmercaptan) is added in manufacturing

Pressure Test:
A pressure gauge does not tell you the level of the gas in the tank; you weigh the tank to determine that. What the pressure gauge does do is allow you to (easily,and frequently) leak test the LPG system.
1. Close all appliance valves.
2. Open solenoid valve, if equipped.
3. Open, then close cylinder supply valve. This pressurizes the gas distribution piping system.
4. Observe the pressure gauge, at the regulator. Note the initial pressure, and insure that it remains constant (no drop) for not less than 3 minutes.
I prefer a 10 - 15 minute test
5. If any pressure drop is noted, check the distribution system for leaks. Use a propane leak detection fluid, or a non-ammonia* detergent solution to perform a “bubble test”.
* ammonia attacks the brass fittings

Bubble Test:
The bubble test enables you to check for leaks by applying a leak detector solution, or thick soapy water, on all connections. The leak detector solution can be obtained from your local propane dealer. Perform this test when installing and filling tanks or cylinders and any time you suspect a leak.
1. Apply leak detector solution, or thick soapy (ammonia-free) water, to the connections between the cylinder valve and regulator outlet and/or any other connections you suspect may be leaking.
2. Slowly open the tank or cylinder valve and watch for bubbles.
3. If bubbles appear, close the tank or cylinder valve and tighten connections immediately (but do not over tighten).
4. Repeat steps 1 through 3 until the bubbles stop. If you cannot stop the bubbles, contact a professional for service.
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Old 14-08-2006, 13:42   #18
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I knew it was odourless and the "smell" was added. But is ethylmercaptan the same weight as Propane so as it also sinks in air or will it dispers faster than the propane and leave the gas behind.
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Old 14-08-2006, 14:51   #19
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Fair enough comment on the switch. My only point was to prevent the pump from kicking on and draining the bilge. For the sake of the experiment I'm assuming that the owner of the boat has decided to try and clear the propane as opposed to...

I have to admit that my biggest DOH moment came courtesy of Wheels, the vent fan. It is designed to vent explosive vapor from the engine compartment. My old C&C came with a gas motor and the fan is still there (in fact I replaced it with a new one.)

With that said I agree that the first thing to do when coming to the dock and finding the boat is full of propane (or a bilge full of gasoline) would be to call the fire department.

Finally there seems to be a wide selection of propane monitors on the market. Anyone found one they like?
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Old 14-08-2006, 23:22   #20
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Originally Posted by Pura Vida
Finally there seems to be a wide selection of propane monitors on the market. Anyone found one they like?
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Old 15-08-2006, 00:50   #21
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Quote:
Originally Posted by Pura Vida
Finally there seems to be a wide selection of propane monitors on the market. Anyone found one they like?
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Old 15-08-2006, 04:36   #22
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This is an interesting problem. The air scoops seem like a simple solution. How about weighing anchor and sailing up wind without using any electric devices, but with all hatches and vents open?

I know that on the anchor with our forward facing deck hatches open the wind is scooped and DOES go quite low into the boat and blow "thru".

I had an awful experience when the engine exhaust hose developed a whole in the spring whilst in the dock. I was in the cockpit observing the "exhaust" (just had some engine work done) and down below was filling with thick smoke. ICK.

When I realized I stopped the engine and tried to see what had happened... Was too thick with smoke. I opened all the hatches and ports... and 5 minutes later all the smoke had disapted... and the boat wasn't even bow to wind. So I think passive ventilation can clear / change the air in the boat. No?

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Old 15-08-2006, 05:26   #23
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If you have propane on your boat, you are supposed to have an explosion proof bilge blower and explosion proof switches just like a gasoline powered boat. The simple answer is turn on the explosion proof bilge blower and let it run until the bilge has been vacated of propane. The nose is a pretty good propane sensor but an electronic sniffer makes a better choice, especially if tied to an autmatic shut off switch.

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Old 15-08-2006, 08:38   #24
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I have a diesel auxilliary and the engine "room" does have a blower which is a squirrel gage type and runs when the engine runs and supplies fresh air to the engine and I suppose some cooling. But I do not have a bilge exhaust fan and I have not seen them on sailboats.

Who has an explosion proof blower exhaust system on their sailboat?

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Old 15-08-2006, 11:55   #25
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Propane detectors

For decades all of the propane detector manufacturers have used the same sensor in their products. The sensor is heated by a small controlled current source and is measured in a bridge circuit for changes caused by various gasses that will unbalance the circuit when calibrated for air.

I have noticed that most alcohols, methane, and propane will set off the circuit. The circuits are very sensitive so that you will be warned well before the number of ppm becomes dangerous. I haven't tried gasolene so don't know if those fumes will set if off or not (don't think so but don't know). Diesel does not set them off.

Because of the current required to drive that same sensor for all manufacturers' products the total instrument current drain is usually on the order of 1 Amp for a 12V product. There have been some solid-state sensors developed yet I don't know if they have made it into the market....anyone know?
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Old 15-08-2006, 13:40   #26
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Yes Rick, Gasloline sets them off. So too does Diesel when it is in a vapour form. Like it has dripped onto a hot'ish engine part and evaporated. So too engine fumes. I had my detector go off because the engine rocker cover breather pipe was originaly fitted into a container to catch oil drips. The hazy fumes would fil up the engine room and set off the detector. So I fitted the hose to the intake manifold to allow the fumes to pass through.
I now have to replace that sensor though. I got wet and now doeswn't work. These sensors are very very sensitive to moisture and will fail if they get wet. I am going to mount the new sensor inside a plastic box with holes in the bottom of it so it will still sense. But if water rises, then the air trapped in the box will hopefully keep water out and it will protect the sensor from water if I have a leak again. Long story short, I had a hose burst ont he pressure side of the cooling pump and spray water all oveer the engine room. I washed the engine room down with fresh water forgetting about the sensor.
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Old 15-08-2006, 15:55   #27
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Your boat is not going to explode...

I bought an old ketch in 1991. Closed it up to go to werk every day, opened hatches when I got home. Often immediately lighted stove to have a cup of coffee, and begin dinner. After TWO weeks, began noticing 'smell'. After THREE weeks, smell was very noticeabe. I said to myself, "Hmmm, that smells like,, eeek, propane! I got down and looked, and there was something that could be a pilot light endfitting. Lit a match to it, pfff, the tiny little pilot flame.

Three weeks of a closed up boat, aired every evening/all night, closed up ten hours every day, with the unlit pilot light spewing propane, and the bilge on this boat was very deep. Didn't explode.

Gasses are quite light, Much lighter than smoke, and can get out of a boat fairly easily. There were two explosions a year apart in St Thomas. Both were caused by the owner closing the boat up tight, and emptiying multiple cans of bug spray, beginning at the bow and working their way back. They'd forgotten about their pilot lights. The gas didn't blow, in both cases, until the sprayerguy got right beside the stove, and the boat was jampacked with spray from three or four cans, or more, propelled by propane. Both explosions were very bad, one man lost both his legs, and the other his life.

I've NEVER heard of a boat blowing up because of the cooker, except one big fire from a pressurized diesel stove(ugh-ugh-ugh-ugh) If propane was so goldarned explosive, then why is it so difficult to get half the burner to light sometimes??????

Just be reasonably careful, your boat's not gonna blow up.

Cheers,

Melissa-cookin'-with-gas-on-boats-for-thirty-years
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Old 15-08-2006, 20:12   #28
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Originally Posted by MelissaK
Gasses are quite light, Much lighter than smoke, and can get out of a boat fairly easily.

If propane was so goldarned explosive, then why is it so difficult to get half the burner to light sometimes??????
We are talking about propane, 1/3 heavier then air, which comes in a liquid form when in storage.

As for your burners, you might try cleaning out the food spills to allow the LPG to get out ALL the little holes.

Fill a balloon with propane and kick it around awhile, you'll see how heavy it really is.............................._/)
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Old 15-08-2006, 22:44   #29
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Quote:
Originally Posted by MelissaK
I've NEVER heard of a boat blowing up because of the cooker, except one big fire from a pressurized diesel stove(ugh-ugh-ugh-ugh) If propane was so goldarned explosive, then why is it so difficult to get half the burner to light sometimes??????
I guess you didn't see that article in Cruising World (or maybe Ocean Navigator?) a year or two ago. I don't remember all the details, but here are the main points: It involved some action that sounded pretty dumb, though I don't remember what exactly. He remembered being about to light the stove, and he remembered lying on the dock wondering why he couldn't hear the people who were talking to him. Later, witnesses told them they saw him thrown from inside the boat onto the dock. Damage to the boat was extensive, but it didn't sink.

Propane certainly IS very explosive when mixed with air. You can get an impressive fireball from the amount of gas that escapes a lab burner in a few seconds. (Never let a lab partner "help" light the burner until after you have confirmed that they know how to do it. The fact that he lit it once before does not count.)

If you have trouble getting your burner to light, then you have obstructions that are blocking the flow of gas somewhere. I have never seen this in a stove, but I have seen it in outdoor gas grills. In that case, I've found the problem is usually either rust or insects blocking the flow of the gas.
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Old 16-08-2006, 05:41   #30
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Non lighting bits on the burner were on (apartment) stoves of yore. Which gayly lighted once fanned with a hand. Not dirty kitchen habits. I don't grill for health reason, Gas grills, the artificial charcoal types, are filthy with dripping grease and burnt specks.

Docked boats are often very poorly ventillated, being not poinetd into the breeze.

nevermind.

Melissa
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