Propane Explosion test

[Ken Juul]

British tv show about sailboat safety.  Last episode shows why safety with propane is so important.  If you watch carefully you can see the propane settle to the bottom of the cabin then slowly fill it up. 

http://www.youtube.com/watch?v=Yxm3uMy6MPI&feature=player_embedded#!

[Ron Hill]

Interesting, but I got the distinct impression that they set out to blow up that boat!!

Don't get me wrong as a propane "leak" is be a very dangerous occurrence. 
The Mk I engine instrument panel has a blower switch and I use it when the first start in the morning after the propane has been ON overnight.  I recommend that others do the same.  The blower will extract any fumes from the aft bilge.

I might also add that the Mk I C34s have 2 vents for the propane box rather than the one required (recent post).  I've always like the 2 vents as one can easily be blocked by a spider nest or mud dobber.

A thought.                                                 

[Fuzzy]

When we're done cooking/using the stove we turn the gas off with the solenoid (and not the burner valve) and make sure
that the flame goes out.  That way we know that the solenoid valve is working and also that there is no gas in the boat
beyond the LP gas locker.
Larry

[Jack Hutteball]

We are paranoid enough that we do the same plus shut it off at the tank.
Jack

[Stu Jackson]

When we're done cooking/using the stove we turn the gas off with the solenoid (and not the burner valve) and make sure that the flame goes out.  That way we know that the solenoid valve is working and also that there is no gas in the boat beyond the LP gas locker.
Larry

No need to be paranoid  , seems like just a good idea and should be routine.  We do that with our CNG on the boat as well as our propane BBQ grille at home.

No reason to keep the hose between the tank and the stove under constant and unnecessary pressure when you're not using the stove or being on the boat.

I do the same with the fresh water system.

[waterdog]

I don't agree that this practice is as safe and low risk as the rest of you believe it is.  

I think we could all agree the safest end state is the stove valves off, the solenoid off, and the tank valve turned off with no pressure in the hose.   Do I do this on my boat?   No.  

On my boat I am most interested in avoiding any state that will put the crew and boat at risk.   My belief, right or wrong, is that a hose full of low pressure propane is not likely to rupture and even with a failure, will not present a significant risk.  

I turn off the stove valves followed by the solenoid.   When we leave the boat, we also turn off the tank valve.   I will never do this in the reverse order or allow anyone operating propane system on my boat to alter the sequence.   Here is why.

We are stupid humans.   We cannot reliably be counted on to have consistent behaviour.   Stuff happens all the time and we forget.

We often forget to turn off the solenoid.   And usually while we are sitting down to eat we notice the light on the panel and we turn it off and point out to whoever left it on that they forgot to turn it off.   Always within minutes we end up in a "safe" state with solenoid off and stove valves off.  My idea of safety, maybe not yours.

Here is what happens when it goes the other way.   And I know this to be true.   One day Tracey baked cookies.   She shut off the solenoid valve and she forgot to turn off the oven valve.    No visual reminder of an "unsafe" condition.  

Later that day, I went to make a pot of tea.   I turned on the solenoid and lit the burner on top of stove.  Fortunately, I smelled gas before we had auto removal of the coach roof.    But it could have gone very badly wrong.

Nobody will ever knowingly shut off the solenoid before turning off the stove valves on my boat, period.  

Your boat your choice as they say, but understand the possible behaviours and the possible consequences in making your risk assessment.  

[Fuzzy]

I believe in what you're saying Steve.  It is always a risk and it does take people to take responsibilty to turn off the burners of
the stove when they turn off the solenoid.  However, turning off the solenoid first confirms that the valve has not failed and is
stuck in the "open" position.  So I guess both arguments have merit.
Larry

[waterdog]

Larry, both approaches do have merit.   And I believe on your boat you are operating perfectly safely.   You have thought it through.   The point is propane is a thinking man's game.    Everybody needs to understand how their system works, what are the points of failure, what are the consequences of failure and how do crew habits reinforce or undermine safety.   

My last boat had a sensor tied in to the solenoid so if gas escapes in theory the sniffer detects and shuts off the solenoid.   I very deliberately have not put this safety device on this boat.    We become comfortable that this little sniffer is going to look after us when we become sloppy and forget to turn the solenoid off.    Trouble is it is another point of failure and it encourages bad behaviour.   

If safety depends on human behaviour, (as it does in so many aspects of sailing) I am totally comfortable with simple practices and communications: "Turn off the switch when you are done or the boat will blow up."   or "It's OK to stand there, but you have to wear a lifejacket so that when the boom hits you in the head and kills you we can easily recover the body for your family."  I still have labelling in the head that reads "turn this lever to the dry position or boat will sink".   (I haven't told my brother in law that the vented loop behind the shower curtain fixed that little quirk - I figure it's still good practice...).   Everybody aboard needs to understand the important stuff and that is not sail trim.   

So the rule is: Do what Stu says, but only if you understand why Stu is saying it.  If you disagree, say so because the diverging opinions help others think the issue through and understand their own boat and practices better.    Oh yeah, and if Stu says get rid of your trailer connectors, get rid of your trailer connectors.

[Ken Heyman]

-------so we have talked about safely operationg the "gas" system but how do we maintain it ?

Ken

[waterdog]

Soapy water on all connections looking for bubbles.  Pressurize, turn off the valve, and make sure the pressure doesn't drop over 15 minutes.  Inspect hose. Replace if any evidence of cracking, wear, chafe.  Make sure hose is secure and not moving around.  You should have a direct run from your box to your stove with no tees or connections in between.   Check operation of solenoid. 

[lazybone]

The first thing that occurred to me after watching the video was that it's rather difficult to blow up your boat with propane.

Reminded me of the NBC 20/20 story about Ford's gas tanks all blowing up when they were rear ended.  After a whole bunch of staged crashes failed to get the job done and NBC needing a sensational story they strapped a lit road-flare next to a puncture and started filming. 
Kaboom, good public service story with good film.
.

[Ken Heyman]

An interesting google search would be the number of boat propane explosions/fires annually. It seems that every year I hear of a gasoline explosion and fire often connected to improper fueling and venting methods. We are fortunate to have diesel engines in that regard. I guess propane and/or CNG are our "most combustible gases" (sounds like a reality TV show).

Ken