Waxy/Oily stuff accumulating in LP propane pipework

[trogstig]

I wonder if anyone has heard of oily/waxy stuff accumulating in (low pressure) propane pipework? Couln't find anything on this subject on t'interweb - except in the context of huge gas export pipelines...

 

My cooker has been suffering from low gas pressure for a while - then last week it ceased working at all.

 

Since my water heater still ran, yet is further down the gas circuit than the cooker, the gas supply was clearly ok.

 

Traced the fault to a blockage at the lowest part of the cooker supply hose. Was just able to blow through this pipe (by mouth), and observed a 'lazy' bubbling whilst doing so.

 

Hung the pipe from one end, hoping for blockage to drain out - no joy.

 

Moved the pipe to a warm place (hanging above the Morso stove), and immediately this oily/way gunk started dripping out.

 

Refitted pipe, tested for leaks (soapy water on connections, then pressure test by bottle gauges) - then the cooker worked

 

For your info: (1) the oily/waxy stuff was yellow in colour; (2) the pipework unions had been fitted with red assembly paste; (3) the cooker has probably been fitted for the 21 years since Waterlily II was launched; (4) the system had been fitted with a bubble tester at one stage, but currently uses a Gaslow auto-changover regulator with gauges, hence no bubble tester is required or fitted.

 

Please. Has anyone got any suggestions about the source of this contamination? I'm worried that this is something (e.g. a flexible hose) degrading in-situ; or otherwise something which needs attention.

 

Thank you.

James.

[johnjo]

I wonder if anyone has heard of oily/waxy stuff accumulating in (low pressure) propane pipework? Couln't find anything on this subject on t'interweb - except in the context of huge gas export pipelines...

 

My cooker has been suffering from low gas pressure for a while - then last week it ceased working at all.

 

Since my water heater still ran, yet is further down the gas circuit than the cooker, the gas supply was clearly ok.

 

Traced the fault to a blockage at the lowest part of the cooker supply hose. Was just able to blow through this pipe (by mouth), and observed a 'lazy' bubbling whilst doing so.

 

Hung the pipe from one end, hoping for blockage to drain out - no joy.

 

Moved the pipe to a warm place (hanging above the Morso stove), and immediately this oily/way gunk started dripping out.

 

Refitted pipe, tested for leaks (soapy water on connections, then pressure test by bottle gauges) - then the cooker worked

 

For your info: (1) the oily/waxy stuff was yellow in colour; (2) the pipework unions had been fitted with red assembly paste; (3) the cooker has probably been fitted for the 21 years since Waterlily II was launched; (4) the system had been fitted with a bubble tester at one stage, but currently uses a Gaslow auto-changover regulator with gauges, hence no bubble tester is required or fitted.

 

Please. Has anyone got any suggestions about the source of this contamination? I'm worried that this is something (e.g. a flexible hose) degrading in-situ; or otherwise something which needs attention.

 

Thank you.

James.

 

No idea where it comes from, but I don't think it's a contaminant that's got into the system, more some sort of residue from the gas, the reason I say this is because I have had two changeover valves that stopped working and when I stripped them down they had blocked with very similar stuff, almost like 'Petroleum jelly'.

 

Perhaps some technical bod will tell us what it is, but I wouldn't panic in the meantime.

Edited December 15, 2009 by johnjo

[alan_fincher]

I have come across something similar, but not exactly as you describe, as I have seen black tar like residues, not yellow.

 

I think it has been discussed in previous threads on this forum, but maybe I've seen it elsewhere.

 

Can't solve your problem, but a few observations, or questions.

 

1) I have seen this discussed on a Calor or other LPG related site, not specifically relating to boats, (it may have related to Mobile homes). The advice is that cylinders and regulators, plus the high pressure pipework are always arranged so that all parts of the regulator, and any change over valves are higher than the valve of the cylinder. Cylinders collect muck after a while, (you can usually hear liquid sloshing around in a cylinder even after it will deliver no gas), and this can get into the pipework beyond it, if things are laid out wrongly. Of course stating that all regulator parts need to be above the cylinder valve is easy - actually finding the space to do it in a narrowboat gas locker may be a very different thing.

 

2) Calor Marine on their site state that jointing compounds should only ever be used in taper type fittings, and that it is wrong to use any type of sealant or tape in compression fittings. It doesn't seem to stop people doing it, and whilst I don't think it explains your problem, it is not unusual to open a compression joint with (say) GasTite in it, and find a half-hardened mass in the gas-way in the fitting, part blocking the flow.

 

3) I don't really understand more than the rough principle of an auto-change-over valve, but I've never seen one that has anything that would obviously perform the same function as a bubble tester, (i.e. to detect whether any part of the low pressure system further on has even a small leak). I would need a better explanation asto how the change-over valve is able to replicate the purpose for which you have a bubble tester.

 

Although the "crap" in your system, (and I am not familiar with yellow"crap"), might be coming from hoses degrading, in my experience crap can originate from the cylinders themselves. What colour are your various hoses ? When were they last replaced. Calor Marine advise to do so, (I think), every 5 years, so your installation should perhaps be on it's 5th set by now ?

[trogstig]

... they had blocked with very similar stuff, almost like 'Petroleum jelly'.

Thanks JohnJo - yes, a lot like petroleum jelly - sounds like the same stuff.

Of course stating that all regulator parts need to be above the cylinder valve is easy - actually finding the space to do it in a narrowboat gas locker may be a very different thing.

Quite - the regulator and HP pipework are as high in the locker as possible, but probably about level with the cylinder valves...

it is not unusual to open a compression joint with (say) GasTite in it, and find a half-hardened mass in the gas-way in the fitting, part blocking the flow.

The blockage was quite clearly this waxy/oily stuff - there was no assembly paste in the drips I collected; just a modest smear on the compression olives/threads.

...an auto-change-over valve, but I've never seen one that has anything that would obviously perform the same function as a bubble tester, (i.e. to detect whether any part of the low pressure system further on has even a small leak).

Sorry - a bit confusing in my original message. The auto-changeover valve, alone, does not provide leak testing - but the pressure gauges let you (1) pressurise the system, (2) note the HP pressure at both bottles, (3) shut off the bottle valves, (4) wait 20 minutes, and (5) observe any pressure drop.

Although the "crap" in your system, (and I am not familiar with yellow"crap"), might be coming from hoses degrading, in my experience crap can originate from the cylinders themselves. What colour are your various hoses ?

HP hoses were new 2 years ago - black in colour; factory made, BS marked hose assemblies.

Cooker hose is galv-braid covered, so cannot see colour or hose material.

When were they last replaced. Calor Marine advise to do so, (I think), every 5 years, so your installation should perhaps be on it's 5th set by now ?

Oh... The cooker hose is at least 5 years old; possibly 21 or so. Perhaps I'd better source a new one then.

Thank you for this important detail !

[Batavia]

I have had a similar experience many years ago, which I have described in a post. In my case, the liquid was a thick oily yellow liquid and had collected in what was effectively a low point U bend in the gas pipework. It could only have come from the cylinder, as I replaced the hose at the same time and cut it open to look at its internal condition.

 

Also, my Sibir fridge stopped working when the internal steel pipework got blocked by an oily rust-type sludge (a contradiction, but nevertheless true) - which I only discovered after I had bought an electric fridge and was stripping the Sibir for bits. As most specs I have seen for Propane specify zero water content, it is difficult to see where the rust came from.

 

It makes sense to design the gas pipework such that any of this material falls to a low point and cannot block the main pipework.

 

Chris G

[alan_fincher]

Oh... The cooker hose is at least 5 years old; possibly 21 or so. Perhaps I'd better source a new one then.

Thank you for this important detail !

In practice, before out last BSS, I decided to renew all the low-pressure braided hoses, (3 appliances), on the basis of the 5 year advice, (they were 13 years old!).

 

If you cut into an old one, mine at least were just the standard "orange" calor hose, with the extra layer of braiding. I could see no obvious visible deterioration of the inner hose at all, and it did not crack or craze if you stretched it heavily. It really did look like it would go another 13 years.

 

However in the shed I have an old Calor blow torch which attaches to it's cylinder by a long length of orange hose, (a very long length, as I have timber at roof level with the bottle still on the ground). That is older, but has gone horribly rigid, and looks almost brittle. I'd certainly not want to use it for gas now, so whilst 5 years sounds unduly pessimistic, some of it at least, doesn't last for ever.

 

Our BSS inspector told us that they were going to be moving away from braided hoses in these locations, simply because you can't inspect the visual condition of the "inner". However I have seen nothing to support that, and believe that both internet suppliers, and chandleries still sell the braided connectors.

[Timleech]

As most specs I have seen for Propane specify zero water content, it is difficult to see where the rust came from.

 

Chris G

 

I think you'll find that the fluid left in an 'empty' gas bottle is often partly water.

That's what they told us when I did a Calor course many moons ago (before Corgi got their sticky fingers into boats ), I've never drained one to check!

 

Tim

[Keeping Up]

A few years ago my CH boiler stopped working, and it turned out to be a collection of oily fluid at the lowest level of the low pressure pipework. I cleaned it out and all was OK, it's been OK since.

 

I also use my auto change-over valve as a regular weekly check, by turning off everything and the two bottles and waiting to see if the arrow has turned to red within 12 hours. It's not a precise test but would let me know if any significant leak occurred.

[trogstig]

I also use my auto change-over valve as a regular weekly check, by turning off everything and the two bottles and waiting to see if the arrow has turned to red within 12 hours.

So... A 12-hour gas system test every week. That's 12 hours without a cup of tea.

 

Gaslow say 20 minutes is enough to observe for a pressure drop; yet Waterlily II still only gets this test once/twice a year.

 

It's not a precise test but would let me know if any significant leak occurred.

 

I would have thought that 12 hours makes it a very precise test - if there is still pressure in the system after the bottles have been closed for 12 hours, I'd be pretty sure there was not even a tiny leak.

Even the BSS inspection only tests for 20 (?) minutes.

[Keeping Up]

There's a difference though. The BSS tester will have first emptied the high-pressure pigtails of any gas they contain. They can hold a surpring amount of gas (especially as we have an additional 2 metres of fixed copper pipework in the high-pressure system as a means of reaching our second bottle which is on the other side of the boat). I don't want to waste this gas to do the test, I just turn off the cylinders, so I leave it the long extra time to allow any leak the chance to empty them for me.

 

I found that my sytem empties the pipes in about 3 days. I had the system checked and it passed the BSS test easily (no discernable leak whatsoever on their digital tester) so I am happy. If it passes the 12-hour test (performed at night so I don't miss out on teamaking time) then I'm content.

[steelaway]

Can it have any thing to do with the water filled gas leak tester?

 

 

Alex

[Paul Evans]

Like Alan (post 3), I'm sure this has been discussed on the forum before and I'm equally sure that I contributed because I had a similar problem. We have a U-bend in the gas locker between the regulator nd the point where the pipework goes through the bulkhead. This became blocked with gunk completely blocking the gas flow and resulting in a cold weekend without central heating or boiled water for coffee. I was told that one of the tail hoses had deteriorated, reacting with the gas to produce the gunk. The hose and U-bend were replaced and - hey Presto - heat and hot water! It sounds as though you should replace the cooker hose even though cleaning it out has solved the problem for now.

[BEngo]

Can it have any thing to do with the water filled gas leak tester?

 

 

Alex

 

 

The oily muck is what is carried over when the propane is separated from the other gases.( just like when Scotch is distilled the bit you want is not pure alcohol but contains the other estrers and phenols and stuff that make it tyaste o

f Scotch not Vodka)) The muck may also contain some of the stuff that the gasd suppliers put in to make the gas smell so you notice a leak ( stenching agent)

 

Watrer in LPG is very common. That is why the BSS dces not permit mild steel pipe work. The water contains dissolved oxygen which enables slow steady internal rusting.

 

N

[eightpot]

When I had my Range Rover, I used to run it on LPG. About every 20k miles, I had to disassemble the vapouriser to clean out the gunk as mentioned in the OP. It is known as "Heavy ends". Google that term and it might throw some more light on the subject.

[PeterF]

Here is a link to one of the topics

 

http://www.canalworld.net/forums/index.php...&pid=242379

 

Also text from my post

 

There have been reports of liquids in regulators on caravans / motorhomes, but I believe this is linked to remote gas regulators with HP hoses between the bottles and resultors rather than the bottle regualtors.

 

See clicky and read the pdf document for details

 

Edited to correct the clicky