Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Search this Thread Rate Thread Display Modes
Old 06-01-2018, 12:15   #1
Registered User

Join Date: Mar 2015
Posts: 16
Propane released when lighting burner

What happens to propane released when lighting a cooker burner. It takes a few seconds to light the burner and in that time a little propane is released. It is heavier than air so I guess it ends up in the bilge. Overtime will it accumulate, disperse naturally or decay?

It is only a small amount but over time does it accumulate?

Anyone know?

Thanks
__________________

NotreVoyage is offline   Reply With Quote
Old 06-01-2018, 16:01   #2
cat herder, extreme blacksheep
 
zeehag's Avatar

Cruisers Forum Supporter

Join Date: Jul 2008
Location: furycame alley , tropics, mexico for now
Boat: 1976 FORMOSA yankee clipper 41
Posts: 18,086
Images: 56
Send a message via Yahoo to zeehag Send a message via Skype™ to zeehag
Re: Propanereleased when lighting burner

i have not yet died nor exploded
knock wood.
i find no trace of it post ignition, which seems to use all the escaped gas.
have fun.
__________________

zeehag is offline   Reply With Quote
Old 06-01-2018, 18:27   #3
Marine Service Provider

Join Date: Dec 2009
Location: St Augustine, FL
Boat: Woods Vardo 34 Cat
Posts: 3,030
Re: Propanereleased when lighting burner

I would assume it evaporates after some time as gasoline does.
__________________
@mojomarine1
Boatguy30 is offline   Reply With Quote
Old 06-01-2018, 18:57   #4
Registered User
 
BlackHeron's Avatar

Join Date: Jan 2016
Location: Chicago -for now...
Boat: Hallberg-Rassy Rasmus 35
Posts: 238
Images: 18
Re: Propanereleased when lighting burner

Good question. LP, "Liquid Propane," evaporates into a gas at the top of the bottle and is drawn off into the hose and through the regulator. It is already "evaporated" after this point. A gas can't evaporate again unless it is first condensed into a liquid again.

Propane gas is heavier than air. It sinks. It can't evaporate, it simply drops down to the lowest place it can settle into. From there, can it slowly mix with the air and atom by atom bounce up and out of the boat eventually?

Like Karen said, I haven't blowed up already.

We have a Fireboy-Xinex LP sensor in our dry bilge as part of the solenoid panel. It goes through a self-test every time it starts up and thereafter monitors the air in the bilge for traces of propane and other dangerous gases. But it isn't quite down at the very bottom of the wet bilge. It wouldn't survive the moisture. Every once in a while I will take my portable gas sniffer and put it down there and check when I'm sniffing around the stove for leaks. It never has shown any trace of explosive gases.

Where does it go? It must migrate out slowly somehow.
BlackHeron is offline   Reply With Quote
Old 06-01-2018, 19:52   #5
Registered User
 
Jammer's Avatar

Join Date: Jan 2010
Location: Minneapolis area
Boat: Morgan 250, 25'
Posts: 410
Re: Propanereleased when lighting burner

Quote:
Originally Posted by NotreVoyage View Post
What happens to propane released when lighting a cooker burner. It takes a few seconds to light the burner and in that time a little propane is released. It is heavier than air so I guess it ends up in the bilge. Overtime will it accumulate, disperse naturally or decay?

It is only a small amount but over time does it accumulate?
Over time propane dissolves in air forming a solution. Between 2.1% and 9.5% propane this solution is explosive. Propane, and solutions of air and propane, are heavier than air and so tend to move downward while being mixed with surrounding air.

But ultimately the bilge is not completely sealed and there is some air exchange over time. The propane diffuses into the incoming air and its concentration gradually drops. Once in solution the propane does not settle out, that is, it does not form a highly concentrated layer at the bottom of the bilge.

Gasoline vapor is both heavier (well, more dense) and more explosive with a wider LEL-HEL range of 1.2%-7.1%. There are far more gasoline-powered boats (with engines below decks) on the water than boats equipped with propane systems. While bilge explosions do occur, they are infrequent considering the enormous number of craft and the comparatively lax standards of maintenance and operation that are applied on so many of them.

While propane is dangerous if handled carelessly, I think the risk is oft times exaggerated.
Jammer is offline   Reply With Quote
Old 07-01-2018, 09:01   #6
Registered User

Join Date: Aug 2017
Posts: 39
Re: Propanereleased when lighting burner

I would bet that it gets sucked into the engine while you are running and disappears. There is quite an air flow through the bilge, especially with a diesel engine. Even though it is heavier than air, the turbulence will no doubt stir it up and it will get used or blown out.
Gypsyjon is offline   Reply With Quote
Old 07-01-2018, 09:12   #7
Freelance Delivery Skipper..
 
boatman61's Avatar

Community Sponsor
Cruisers Forum Supporter

Join Date: Jan 2010
Location: PORTUGAL
Posts: 22,024
Images: 2
pirate Re: Propane released when lighting burner

I think any that 'gets away' before the burner ignites goes up at the same time.. that's why sometimes one gets that 'Woosh' as it lights if the first try fails..
Doubt if any gets to the bilge..
__________________


Born To Be Wild
boatman61 is offline   Reply With Quote
Old 07-01-2018, 09:17   #8
Registered User
 
BlackHeron's Avatar

Join Date: Jan 2016
Location: Chicago -for now...
Boat: Hallberg-Rassy Rasmus 35
Posts: 238
Images: 18
Re: Propanereleased when lighting burner

Quote:
Originally Posted by Jammer View Post
Over time propane dissolves in air forming a solution. Between 2.1% and 9.5% propane this solution is explosive. Propane, and solutions of air and propane, are heavier than air and so tend to move downward while being mixed with surrounding air.

But ultimately the bilge is not completely sealed and there is some air exchange over time. The propane diffuses into the incoming air and its concentration gradually drops. Once in solution the propane does not settle out, that is, it does not form a highly concentrated layer at the bottom of the bilge.

Gasoline vapor is both heavier (well, more dense) and more explosive with a wider LEL-HEL range of 1.2%-7.1%. There are far more gasoline-powered boats (with engines below decks) on the water than boats equipped with propane systems. While bilge explosions do occur, they are infrequent considering the enormous number of craft and the comparatively lax standards of maintenance and operation that are applied on so many of them.

While propane is dangerous if handled carelessly, I think the risk is oft times exaggerated.
So basically it diffuses as it mixes with the air, but that takes a little time at first and it tends to settle to the bottom of the air in the boat before it can slowly mix evenly with the atmospheric air above it.
BlackHeron is offline   Reply With Quote
Old 07-01-2018, 10:08   #9
Moderator
 
sailorchic34's Avatar

Cruisers Forum Supporter

Join Date: Feb 2011
Location: SF Bay Area
Boat: Islander 34
Posts: 5,086
Re: Propane released when lighting burner

Assuming 10 seconds of propane leaking before lighting (which is lots) and a 6000 btu stove top burner, you're looking at 0.00015 pounds of propane. After the burner lights the heat of combustion causes the air around the burner to be drawn towards the burner. More then likely the leaked propane is burned and consumed as air is drawn towards the burner.

Having lived aboard for 13 years now, it's never been an issue.
sailorchic34 is offline   Reply With Quote
Old 07-01-2018, 10:39   #10
Registered User

Join Date: Jan 2018
Posts: 6
Re: Propane released when lighting burner

Never been an issue. However, when sailing with the army in the old days from British Kiel Yacht Club. You had to make a log entry every hour and update you DR on a thing called a paper chart! At the same time the crew had to pump the bilge. The rule was pump dry them 10 strokes for gas! The instructor was wonderful Capt Ken Hazard!!!
Flextron is offline   Reply With Quote
Old 07-01-2018, 11:02   #11
֍֎֍֎֍֎֍֎֍֎

Cruisers Forum Supporter

Join Date: Apr 2006
Posts: 13,986
Re: Propane released when lighting burner

I think it is Brownian motion, the random movement of the gas molecules, that eventually diffuses the propane into all the rest of the air in the boat, and since that is hopefully way below the explosive threshold, eventually the "not quite air" gets circulated out of the boat and the danger doesn't build.

With natural gas ashore, there is a distinct odor added to the gas so you can tell if something is leaking. (Methyl mercaptan?) I know I can "smell gas" but have never detected that odor, even in a closed room, after a stove or other gas appliance was lit. So I expect part of this is because very very little gas escapes before the flame, and much of that combusts with the flame.
hellosailor is offline   Reply With Quote
Old 07-01-2018, 11:53   #12
Marine Service Provider
 
boatpoker's Avatar

Join Date: Nov 2008
Location: Toronto, Ontario or Bahamas
Boat: Benford 38 Fantail Cruiser
Posts: 2,984
Re: Propane released when lighting burner

I press and hold the igniter before I open the valve. Time to combustion measured in microseconds.

Quite comfortable that any gas in the vicinity of the burner is ignited.
__________________
That hysterical laughter you hear as you sail a way in your "new" boat ..... is the seller.
boatpoker is offline   Reply With Quote
Old 07-01-2018, 13:04   #13
Registered User
 
Sailshabby's Avatar

Join Date: Jan 2011
Location: Deltaville, VA
Boat: Baba 40
Posts: 187
Re: Propane released when lighting burner

To add to the general consensus, keep in mind 100% if the excess propane isn’t rocketing into the bilge. Some, if not all, is being diffused and “carried” by the drafts found in your cabin.
Sailshabby is offline   Reply With Quote
Old 07-01-2018, 13:15   #14
Registered User

Join Date: Jan 2016
Location: Ventura, California, USA
Boat: Catalina 30
Posts: 182
Re: Propane released when lighting burner

Assuming the spark igniter is working properly, I doubt that any measurable amount actually escapes combustion in the moment of ignition.
If you’ve never tried it, light your burner at night, with the cabin lights off. You may be surprised at the fireball that is invisible in higher ambient light levels. Even the steady burner flame will appear quite a bit higher in the dark.
Brewgyver is offline   Reply With Quote
Old 07-01-2018, 13:31   #15
Marine service provider
 
newhaul's Avatar

Cruisers Forum Supporter

Join Date: Sep 2014
Location: puget sound washington
Boat: 1968 Islander bahama 24 hull 182, 1963 columbia 29 defender. hull # 60
Posts: 5,477
Re: Propane released when lighting burner

Ok propane released when you turn on a 6500 btu burner is .184 oz per second. So its really not enough to even think about. Besides it is usually consumed in the initial burn / just enough to fill the burner itself prior to ignition.
__________________

__________________
Non illigitamus carborundum
newhaul is offline   Reply With Quote
Reply

Tags
lease, lighting, propane

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Recommended lighting By Invitation Construction, Maintenance & Refit 0 27-03-2006 07:48
Marine lighting source? By Invitation General Sailing Forum 5 27-01-2006 16:24
Lighting Tutorial GordMay Electrical: Batteries, Generators & Solar 12 30-10-2005 13:25
On-line Lighting Course GordMay The Library 0 03-06-2005 12:20
Some Marine Lighting References GordMay Electrical: Batteries, Generators & Solar 5 29-04-2005 18:53



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 00:07.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2018, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2018, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.