Gas piping

alahol2

alahol2

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Joined
22 Apr 2004
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Location
Portchester, Solent
www.troppo.co.uk
I have just replaced the 20+ year old butane bulkhead regulator with a dual fuel 'marine' regulator + pigtail. When I came to try the cooker, I couldn't get it to light, virtually no gas coming through. After much messing about I decided to try and 'rod through' the old copper (1/4") piping. I used a length of single core plastic coated wire. I could only get about half way along the pipe from each end. Each time I pulled the wire out it was coated with a foul smelling oily substance. I rodded it several times until the wire came out relatively clean and I finally have a very good flame at the cooker. I use Calor butane.
Questions...
Is this oily substance a by product of the gas?
Is there a filter that can be inserted in the line to prevent the oil from getting into the pipe?
The copper pipework is now 35 years old should it be replaced?
 
This problem has been widely reported in motorhome magazines and forums. It happens when liquid fuel slops into the HP flexible pipework between the bottle and bulkhead regulator, where it reacts with the rubber lining. All-metal HP hoses are available (I have them) to avoid this.

Copper does tend to work harden with vibration and it might be a good investment to change it after 35 years. Although 1/4 inch is probably OK it is normal now to go up a size to 8 mm 5/16 inch.
 
alahol2 said:
Thanks Vyv, I'll have a google. Is this the type of hose I should be looking for?.. http://www.gasproducts.co.uk/acatalog/Gaslow_450mm_Butane_S_Steel_Gas_Hose.html#a01_2d6010SS
Click to expand...

I have delt with gas products for years and a good company, however before you order have you measured the length of pipe you need!
If it is too short you will not get the cooker out to fit it, those pipes are available in differant lengths 'I think' up to 900mm in length as there is a legal limit.

I also ordered the 8mm copper pipe and fittings from them together with a new regulator, and don't forget a gas bubble detector http://www.gasproducts.co.uk/acatal...?utm_source=googlebase&utm_medium=feedmanager

Mike
 
Caer Urfa said:
before you order have you measured the length of pipe you need!
If it is too short you will not get the cooker out to fit it,
Click to expand...

If I have understood Vyv correctly this is a high pressure pigtail to fit between the bottle and the regulator. According to Vyv, this is likely to be the source of the oily substance blocking my pipework.
 
The oily residue is "heavy ends", they are compounds including the stenching agent that do not easily vapourize and normally don't get past the regulator as the regulator is supposed to be mounted above the level of the cylinder outlet and this allows the residue to run back to the cylinder, (not always possible onboard).
No real need to fit a filter as I think they cause more problems than they cure.
And yes I would the replace copper at that age.
 
Looks like I should be looking at replacing the copper then. I may just leave that till next season. I don't fancy having to remove loads of carpet sidelining, which covers the pipework, this year. I've more urgent things to do (like replacing the cabin windows).

Thanks all for the advice.
 
The cause of the problem is that the liquefied gas leaches the plasticiser from rubber high pressure hoses. These are the ones between the bottle and a bulkhead regulator. Rubber hoses are OK on the LP side because these sticky deposits do not get through the regulator, although they can be blown into it, causing it to fail.

The stainless hose tails aand a bit more explanation are shown here http://www.thegaslowcentre.co.uk/ma...8-lh-stainless-steel-0-45-metre-gas-hose.html
 
alahol2 said:
If I have understood Vyv correctly this is a high pressure pigtail to fit between the bottle and the regulator. According to Vyv, this is likely to be the source of the oily substance blocking my pipework.
Click to expand...

The gas pipe you have shown is for fitting from the cooker to the end of your copper piping run near your cooker.

My copper pipework ended up behind the cooker and I did not want a fixed pipe to the fixed cooker as I may need to get the cooker out at some date for maintenance,These reinforced flexable pipes are also used on gimbled cookers to allow movement.

On my system I have approved rubber gas pipe from the gas bottle regulator to my 'bubble detector,I also fitted another shut off valve, after the bubble detector I used 8mm copper pipeing from the my cockpit lockers to the galley behind the cooker.
You will also note the gas bottle is in it's own sealed 'approved' gas locker.

Hope this might help

Mike

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vyv_cox said:
The cause of the problem is that the liquefied gas leaches the plasticiser from rubber high pressure hoses. These are the ones between the bottle and a bulkhead regulator. Rubber hoses are OK on the LP side because these sticky deposits do not get through the regulator, although they can be blown into it, causing it to fail.
Click to expand...

In that case the problem is caused by something else because the oily substance is in the low pressure copper pipes inside the boat. The old regulator was working when removed, not blocked, I replaced it because it was suffering from corrosion on the outside. There are no rubber hoses inside the boat except for the connection to the cooker which has stainless re-inforcement similar to that mentioned by Caer Urfa.

Caer Urfa said:
The gas pipe you have shown is for fitting from the cooker to the end of your copper piping run near your cooker.
Click to expand...

The pipe I linked to is a HP hose. From the description..."Gaslow stainless hose. Length 450mm for connection between the butane cylinder and the 30mbar regulator. Long term replacement for the high pressure rubber hose. Life of 20 years."
I do have a stainless braid covered LP hose, similar to yours, to attach the gimbled cooker to the fixed pipework.
Your gas locker looks very neat. Unfortunately my gas locker is very small with space for only one Calor butane cylinder and a bulkhead regulator. I did consider fitting a bubble tester but there is just not the space. I wouldn't be able to get the bottle in and out if there was anything else on the walls of the locker.
 
alahol2 said:
In that case the problem is caused by something else because the oily substance is in the low pressure copper pipes inside the boat. The old regulator was working when removed, not blocked, I replaced it because it was suffering from corrosion on the outside. There are no rubber hoses inside the boat except for the connection to the cooker which has stainless re-inforcement similar to that mentioned by Caer Urfa.
Click to expand...

I wouldn't discount the mechanism entirely. All the studies have been carried out on camper vans, which don't heel very much. I guess it might be possible for liquids to wash the deposits right through with 30 degrees of heel.
 
vyv_cox said:
I wouldn't discount the mechanism entirely. All the studies have been carried out on camper vans, which don't heel very much. I guess it might be possible for liquids to wash the deposits right through with 30 degrees of heel.
Click to expand...

Good point. The gas bottle is normally open when we are sailing and it could well be that the liquid gas may manage to reach the regulator and beyond. I cant really arrange the piping in such a way as to prevent it (swan-neck) because the locker is so small. I think I'll try one of the pigtails you suggest and see how it goes.
Thanks
 
Caer has by the look of it installed the bubble detector and fittings,with several new joints involved,in an unventilated/undrained locker that is used to store other things.My surveyor told me that since I couldn't fit a bubble detector in the pucker gas locker,due to limited space,it was a bad idea to put it in the adjacent general locker that extends down into the bilge.I see the point in this because I would be breaking into an otherwise imperforate copper line which otherwise has no joints between the gas locker nozzle and the nozzle adjacent the hob.When I find a qualified marine LPG fitter I will ask him or her.
 
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