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Old 02-10-2015, 09:24   #1
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Methane Accumulation

We live aboard. We have a head that burps gas a few times a week. We use a powerful tank bubbler for 20 minutes every hour on a timer so I think this is coming from residual in the lines and Electrosan. However, last week our bilge alarm went off (we could not figure out what was wrong and it was very periodic, so we have had to turn it off) The last couple of days we have actually detected a gaseous smell. Is it possible for methane from a head to accumulate over time in such concentration it is dangerous from an explosive perspective? We are on a catamaran with bunks up high in a well ventilated cabin so we have not been as concerned with breathability .. although at this point we are beginning to get so.

Today we are going to use evacuation fans on deck with hoses to the bilges to vent the boat. We will also be turning the alarm back on and not staying on board if it persists ... but we still wonder if methane could cause this.

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Old 02-10-2015, 09:47   #2
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Re: Methane Accumulation

No, Methane is lighter than air , however hydrogen sulfide is not and could collect in the bilge. Hydrogen sulfide is deadly so you plan of action is a good one.

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Old 02-10-2015, 12:50   #3
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Re: Methane Accumulation

Methane has no odor. Hydrogen sulfide has (rotten eggs) and, in addition to being deadly to breath and heavier than air, is explosive in the right concentration.

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Old 02-10-2015, 12:59   #4
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Re: Methane Accumulation

What sort of bilge alarm Do you have that is going off most alarms are only able to detect certain things What is yours designed to detect That might narrow down what the problem is
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Old 02-10-2015, 13:34   #5
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Re: Methane Accumulation

A. Bilge alarms (I assume you mean a propane gas detector) are sensitive to moisture. It could be false.
B. It is FAR more likely to be a propane issue. Leak test the system.

As people have stated, methane rises; collecting enough from a rare toilet burp is impossible. Yes, H2S can be toxic, but the smell would be strong enough to make the boat completely unlivable first. People seldom die from farts, and that is what you are questioning.

Check the propane system first, just to be certain. Check the sensor and then turn it back on. Then find out why the head is bubbling. By far the most likely problem is a blocked holding tank vent. What else would supply the pressure to push the gas through the head? The fact that you have a bubbler only increase the required gas flow through the vent. It also greatly reduces the amount of methane in the gas.
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Old 02-10-2015, 13:43   #6
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Re: Methane Accumulation

Originally Posted by thinwater View Post
People seldom die from farts
Not to hear my wife tell itů


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Old 02-10-2015, 14:31   #7
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Re: Methane Accumulation

A cautionary note on the effects of Hydrogen sulphide.

In small concentrations it has a very distinct smell (rotten eggs) but in increasing concentrations one quickly losses the ability to smell it. In effect, your nose is overloaded and you loose this "early warning" sense.

The upshot of this is if you smell Hydrogen sulphide and then for no apparent reason, the smell disappears, get out of the area fast.
All men dream: but not equally. Those who dream by night in the dusty recesses of their minds wake in the day to find it was vanity: but the dreamers of the day are dangereous men, for they may act their dreams with open eyes, to make it possible. T.E. Lawrence
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Old 03-10-2015, 03:44   #8
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Re: Methane Accumulation

Greetings and welcome aboard the CF, syblackwell.

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