Gas Safety

[tome]

Returned Monday from a lively sail around the Solent - ran back from Yarmouth to Chi Bar in 3 hours under tiny jib, I think the spray hood was giving us an extra knot! Recorded gusts above 40 knots off Gurnard.

Had a Corgi plumber on board who took a look at my installation including new Plastimo Neptune 2000 cooker. He reckons you'll always get some leakage from burners and recommends turning gas off at locker with flame still alight to empty gas from pipes, not forgetting to turn off burner afterwards. Sounds like good advice and now part of my new procedures. Thought I'd share this, though not wishing to teach granny to suck eggs etc.

 

[incognito]

When arriving at the boat, put a Wickes' smoke detector to the lowest part of the bilge, and if no alarm, light a match to burn off any collected gas. Even if the alarm doesn't detect it, you can be sure that there is nothing there after the lit match.

 

[chas]

Agree entirely. Gas should always be off at the bottle when not in use. Perhaps as important is to make sure that you have a clear drain overboard from the gas locker - not through cockpit drains which exit below the waterline (as my boat had when I bought it!)

 

[tome]

Didn't realise that a smoke detector would detect gas also?

 

[tome]

I've always turned gas off at the bottle, but never drained gas from the pipes using the burner before. I have a gas locker with overboard drain just above WL and recently replaced the plastic skin fitting with a bronze one.

 

[graham]

A smoke detector wont reliably detect gas and checking for leaks with a lit match is really dangerous advise. boat gas alarms are available .

If you get your nose down in the bilge (LPG is heavier than air so will pool at the lowest point).You would smell it .

I strongly suspect the smoke detector / match advise is either a wind up designed to get dozens of horrified replies.Or at best very dodgy advise on a subject they know sod all about.

In my opinion safety matters are not suitable subjects for having a sly snigger about.

 

[tome]

Graham

Suspect you're right about the wind-up.

Only problem with gas detectors is that they need to be in the lowest part of the bilge, but are very susceptible to moisture and easily destoyed by bilge water! The plumber suggested a gas probe (sniffer), but I can't see one under £400. I guess the answer is prevention.

I certainly won't be using a lit match and heartily agree with your comments.

 

[jimi]

I've been tolld that in the event of gas getting into the bilges, (which it should'nt if proper precautions are taken) then the only safe way of getting rid of it is to manually pump the bilges.


<i>Jim</i>

 

[Rob_Webb]

The advice to use a match to check for gas in the bilges is either astonishly stupid or astonishly malicious..... either way, ignore it.

 

[Rob_Webb]

A gas detector is obviously a good backup because it should be silently checking your bilges 24x7. However, if you have any reason to suspect you might have a build up of gas in the bilges, you should make use of that incredibly sensitive instrument we are all blessed with - your nose. I kid you not, if you are in good health, you can rely on this to detect very low concentrations (part per million) well below the dangerous level.

 

[Chris_Robb]

Install a remote gas selanoid switch - makes the job easy so that people actually turn it off EVERY time. Try Calor Gas in Southampton

 

[Chris_Robb]

Re: Is this not the old Irish Leak detector NM

...

 

[Whiskey2]

An extra 20 strokes on the bilge pump is the precaution we use on arriving at the boat. Mel

 

[incognito]

OK, use your nose if you think it is a better sniffer (try some experiments in a totally safe environment !!) and THEN, WHEN YOU ARE SURE YOU CAN ONLY HAVE A VERY LOW CONCENTRATION POOL, IF ANY - light the match.

You who accuse me of dangerous advice - cos it runs counter to the norm - think a little before you hammer on.

How many people light matches or lighters to ignite their gas cookers on the boat, pray? And they do it with NO TEST AT ALL, OF ANY SORT!! They could well be standing in an ever-increasing pool, cos that is what gas does - 'pool'. Moving about in it dilutes it with air, so as to make a more explosive mixture.

The point of this advice is to avoid buildup. Without destroying the very low levels of gas which were referred to in the original posting (left in the pipes after use) they will build up, there is nowhere for them to go.

Bilge pumps only move the air backwards and forwards - well-known fact - they are liquid pumps, not gas - and as you experts will know, gas is compressible, unlike liquid.

Like I said, try some simple experiments for yourself, then come back and slag me off. And, please, don't let any poseurs (sorry, posters) claim CORGI fame !!!!

 

[Joe_Cole]

I am intrigued. You detect some gas and then, because you've decided that it's only a small amout, you light a match. How did you determine that it was only a small amount? For my money if I detected ANY gas I wouldn't light a match: far too dangerous.

I've seen the effect of a gas explosion in a confined area and the two people who were in it were lucky to escape with their lives.

Joe Cole

 

[peterb]

There's been a conflict in advice from the major bilge-pump manufacturers. One has said that bilge-pumps are designed to pump liquids, and cannot be relied on to pump gases. Another has pointed out that in order to be self-priming a bilge-pump must be able to pump gas. Think about it. If your pump is sited at deck level, let's say a metre above the bilge, then in order to draw up water it must first suck up the air/gas in the pipe to the bilge. If it can't do this then it can't pump liquid.

A bigger problem is that even the biggest hand bilge pumps will only pump about 100 l/min. If you've got a serious gas problem in the bilge, then you'll need to pump out several times the volume of gas in the bilge (because the gas becomes diluted as you pump). Look at the volume of your bilge, and multiply by 10. I would be surprised if the answer comes to much less than 1000 litres, so you would need to pump at maximum rate for about 10 minutes. The odd 20 strokes is not going to do much good.

There are some so-called "smoke detectors" which will detect gas. But smoke detectors complying with British Standards work on different principles (optical or ionisation chamber), and should not be sensitive to low concentrations of gas. Ionisation chamber detectors may operate in response to high gas concentrations, but by then it may be too late.

Much better to have a real gas detector. Even here there may be problems; many of the sensors are sensitive to water, and the chance of getting splashed in a bilge is quite high. The best system I've seen is one in which the sensor is mounted well above the bilge, with a pipe from the bilge to the sensor. A "squeezy ball" pump pulls some of the bilge gas up to the sensor when a test is required. No, it isn't on watch continuously, and it isn't automatic, but it works and is likely to keep on working.

Incidentally, if you want to test a gas alarm there are several possible ways to do it. The easiest is to take an empty squeezy bottle (e.g. washing up liquid), half fill it with cotton wool, add a few drops of petrol and cap it off. A puff near the detector should set it off. Or if you want to make sure that your detector is tested regularly, let it be known that if you take a large sip of whisky and then blow on the detector, it should alarm. On some boats the detector gets tested several times an hour!

 

[tome]

Thanks Peter B

Informative reply. Where can I find out more about the 'squeezy ball' pump, this makes a lot of sense.

Regards
Tom

 

[Guest]

Re: GAS SAFETY.

I am a CORGI Registered Installer and am licensed for domestic LPG installations,and whilst I would agree with the advice given about turning off at the bottle,I would disagree that you will always get some leakage from the burners,as if this is the case then the burner control valves are letting through.The gas seal in these is usually by means of a graphite grease seal on a tapered brass plug (not unlike the old sea toilet sea cocks) They should be regularly serviced.If a control knob is either very stiff to turn or exceptionally loose - get them seen to quickly.
You say that your Neptune cooker is new therefore presumably it was properly installed in which case a soundness test would have been carried out on the whole installation so should be OK.
I would also advise all boatowners with old cookers to ditch them and have a new one fitted incorporating flame failure devices. How many times have people turned the gas down to simmer and later found it blown out.
AS FOR THE UTTERLY DANGEROUS COMMENTS MADE LATER IN THIS THREAD AND UNBELIEVABLY LATER REPEATED ,ABOUT USING MATCHES TO DETECT GAS SPILLAGES.
I just hope nobody follows this stupid advice.I have witnessed the effect of a naked flame on a very very small amount of pooled propane in a confined space.Totally agree with poster Graham that it is not a subject to be ridiculed.

 

[incognito]

Re: GAS SAFETY.

Never advocated anything so stupid as using matches to DETECT gas spillages.

What are you suggesting happens when people light their stoves?

First, I have to endorse the statement that the proper thing is to fit a gas leak detector. Nuff said.

The point originally posted related to tiny dribbles of residual gas in pipes. HAVING MADE A TEST. As a 'CORGI Registered Installer ...licensed for domestic LPG installations' you will know that smoke detectors and most noses are incredible at detecting very almost immeasurable levels of gas. The point of flashing-off is to remove any trace of gas (oh no, they never told you, on the CORGI Registered Installers course, that is a standard mine technique for maintaining low levels of residual gas in coal mines).

I should have identified that this suggestion does NOT apply to deep bilge boats, but only to the BenJenBav type saucer bilge boat.

The effect, in a confined space you refer to is explosive: when in the well-aired, unconfined space of a boat, actually amounts to nothing more than the match flare lasting longer than the usual flare - or a gas lighter flaring on ignition.

As to bilge pumps, they will only remove gas/air if pulling a column of water behind them, ie when pumping water as well. Try reading the manufacturers literature. IF you are rightly unhappy about my suggestion, then a far better alternative would be to sweep and whoosh the bilges on a BenJenBav type, with the hatches open - trying to imagine that you are doing it with a real liquid.

If we listened to everyone who concentrated on the danger of things, rather than handling them with common sense, we would still have men with red flags in front of our cars.

 

[jimi]

Re: GAS SAFETY.

With due respect,sir, the use of a naked flame in a coal mine was utterly forbidden. Smokers were searched to see if they had matches and I know that the miners themselves applied rough justice to those who carried matches down the pit.

Jim