Plasticisers out of propane hose - this happen to anyone??

[Redhotsal]

I can't believe that I am the only bod in the UK that has ever had this problem.....

After about seven years of constant trouble free use my minor set up (6kg propane and oxycon) suddenly started to emit "STUFF", which appeared to be a grease-like non flammable substance. It is a real pain as it is propelled out of the torch and splatters out onto the desk and wall. To the touch it is oil-like and has a pungent smell. The torch gurgles away with intermittent ejaculations of this and of course the flame looks like a cheap and nasty firework. It is impossible to use the torch until it has all been blasted through with an air line.

The Calor gas people reckoned it was plasticiser coming out of the propane hose and could not possibly be contaminant from the propane bottle. They reckoned that above 2bar pressure the propane can leach the plasticiser out of the hose and that is what is happening.

My question - why above 2 bar since (isn't that normal operating pressure?) I have a 0-4bar regulator and why now after years and years of trouble free operation? I have always been extremely fastidious in bleeding off the gas from the hoses at the end of each session.

So, anyway - reckoning it was probably about time to change the hoses anyway I got a new set and everything was fine for a day or two and then it started happening again.

I can accept that I should have possibly changed the regulator aswell (even though presumably the flash back arrestor would prevent back flow?) but am not convinced that new hoses should break down so quickly.

THEN - I noticed that it seems to be linked to the weather. No problem in the morning but as the sun hits the set up directly in the afternoon then that's whan the problem starts. I'm wondering if its possible that the recent sunny weather has caused the propane to expand and increase in pressure somehow??

Hiding the set up in the shade this afternoon has dramatically reduced the spitting - there is still some residue left and the torch actually "gurgles" with the wretched stuff but it definitely helps to keep the hoses cool.

Anyway - I would be extremely interested to hear from anyone else who has had anything like this happen to them so we can compare notes. Or if there are any experienced gas bods out there or Boro Boys that might be able to offer me an opinion??

Chheeeeers

Sal

[Les]

wow that is odd behaviour !!!!!!

sorry I can't be of any use to you Sal.... I'm just as mystified as you must be

Hope you get it sorted properly real soon though ....

xx

[BlueMoon]

We had that exact problem with our studio setup when running propylene and using hot head torches for our beginners classes. It was sort of a green gunk that built up in the hose. I was very good about hanging the hoses after each use to allow the gunk to drain. If I did not do that, i would on occasion have bursts of flames shooting from the torches.
I talked to an engineer about it and what you are saying is exactly what he told me. That is was the plasticisers in the hose tube leaching. That is also why the hoses became more stiff after awhile. It is the plasticisers that give the rubber it's flexibility.

But, I have never had this problem with propane. But I run the propane pressure much lower than what we used to run the propylene on the hotheads.

And yes, temperature is directly related to pressure in the tank. The hotter the tank is the higher the pressure. But the regulator should be taking care of the extra pressure.

Can't help you much Sal, I've not experienced these problems with a propane set up but it sounded so similar to our problem on propylene that I thought I'd share it with you.

Jim

[Mary]

Could it be the wrong gas in your tank? Maybe it has been filled with the wrong thing at some point in its career? Just thinking, since Jim has had it happen with propylene.

[Redhotsal]

Hey Jim!

Long time no "see!" How're doing? It's good to talk to you again. 
Actually, although you say it's not much help, in fact it's just great for me to hear from someone else who has something similar happen to them, so thanks for sharing. True about the bursts of flame! It's odd as the greasy stuff doesn't actually burn by itself, but I guess it blocks the nozzles for a second or two hence the Flamethrower effect when it clears. It's quite a wake-up when it happens! 

Just out of interest - is Propylene the same as Mapp gas? I was discussing bulk propane set up somewhere else on the forum tonight. I am of the opinion that Propylene is freely available in the States in large volume cylinders - i.e. bigger than the little cylinders that screw directly onto the Hothead. Is that the situation in the States?
I think it's the case that we can't get Mapp in bulk in the UK so we substitute propane.

But anyway, thanks for sharing info, Jim. I have a suspicion that my regulator may no longer be doing the job properly, so it's next on the list for changing, but in the meantime I'll keep the hoses and tank as cool as I can and see if that sorts it out.

Hi Mary - I have to say my first reaction was that the wrong gas - or rather, I thought some form of contaminant had been put in the tank, although this has happened with two or three different tanks. The Calor man was absolutely adamant that this could not happen and I was lectured on "computer controlled filling" and "high specification gas product" etc etc. He actually almost sounded offended that I could believe there was any problem with the actual propane - lol! It's odd though - never had this propblem happen in th years I've been doing this..... 

Sorry - forgot to add - Thanks for the sympathy Les!   

[BlueMoon]

Sal....from what I understand MAPP & Propylene are very similar. In Texas, we can't get MAPP in the large cylinders but we can get Propylene. It behaves much like MAPP. I used the large propylene cylinders to run a 4 hose manifold out to 4 hot head torches. It was a pain in the butt to hang and drain these hoses after every use. I have finally gone back to teaching that beginners class once a month on the small 1 pound MAPP cylinders. After all...it is what the students will go home with if they buy a beginners hot head kit after the class. If they go bulk propylene they will have to deal with the hose problems same as I did.

But like I said.....I have never had a hose problem with propane on our mixed fuel torches (Minor burners). We use only GRADE-T welding hose for our propane hoses. Is that a nomenclature that is used in the UK for hose rated for propane? You might want to check on that.

Sal...nice to talk to you again. I've been kinda scarce around here for awhile. Trying to get outta my shell a bit...LOL

Jim

[Ian Pearson]

Sorry to hear propane probs Sal. My experience is that I havent had what you have. I have used BOC approved propane hoses, orange colour, for 16 years no probs. Changed my regulators about every 8 years as well as flashback. I do know temp affects propane cylinders it being LPG. In winter with cylinder outside I cant get enough pressure due to cold. I run at 3-4 bar. Have you flushed propane hoses with oxygen? Not the done thing really and only seen it done once-it helped as long as you make sure no residues left. I will ask other boro boys and see what gems they come up with.

Ian

[ejralph]

Somwhere in the back of my head, I remember reading discussions about this.

Only the concensus then was that the gunk is the odourant they put into the gas - some form of pungent oil so you will know if there is a gas leak.

Have you tried a different bottle of gas? (maybe get one of those diddy 3 or 4 kg ones just to have as a standby and use for these sorts of tests? But get it from a different supplier maybe?)

It strkes me as odd that you would get it from a new hosing. I mean, if there is THAT much of the gunk in the gubbins, then surely you would have seen it oozing and schmoozing when you changed all your hosing? For there to be enough residue in your regulator and flashback to contaminate a second hoseline just doesn't feel right to me (incidently, how would enough of that residue travel back UP the hose if it really is plasticizers from the hosing, to the extent that it would contaminate a second hoseline?)

I am sure the plasticers do leak from the hosing, and if they are anything like the plasticers we used to leach from polyclay, then very greasy to the touch. Just for there to be that much of this gunk seems odd.

If it were me, I think I would try getting some gas from a different supplier, different bottle and just maybe try to rule out contamination myself. Afterall it suits the gas man better if the problem is your hose than his gas.

Emma

[greenbeadenvy]

I'm Sorry Sally but you have a torch poltergeist and you have no choice but to give me all the haunted beads you made(for your own safety you understand) and call for an exorcism

[ejralph]

Best be on the safe side and send me all your glass to look after too....

Emma 

[Les]

Maybe you should christen your torch 'Regan' from here on in....

[silverlemon]

Hi Sal, sorry to hear you're having problems. 

This sounds very similar to what happens with my 2 small soldering torches, the sort you fill with lighter fuel.
It spits, crackles and jets erratically when it's very full, until the quantity of gas is correct for the torch. It's making me wonder if it's a pressure thing, especially with the hot weather affecting it.

Does this happen when the bottle is new or when it's half full also?
I think Emma's right to wonder why the new hose would do the same immediately.

I can't help thinking that the goo is more likely to be part of the propane mix itself, after all, it is a compressed liquid in the cylinder. Maybe it would help to change your regulator, maybe this isn't regulating the pressure and flow rate so well as it used to.

Also what end is your flashback arrestor? Is it next to the regulator or up just behind the torch? I was thinking that if it's near the torch then it may be more likely to have plasticisers (if that's the problem) stuck in it than if it's next to the regulator, or do you think that the plasticisers would have run back down the hose during use or after it and built up on the sintered disc? I know nothing of how the plasticisers would travel in the tube so this is all conjecture, but I do know that a sintered disc is crushed metal that is compressed into a porous like layer of material, and can be made with different gaps between the particles so that it screens different things. This is how it allows the gas to go through it while forming a physical barrier to any stray flames. We used them in gas detection company I worked at to allow the gas near our sensors where the equipment would do a mini controlled ignite of the gas inside a tiny chamber to see if the gas exploded, but without igniting the gas outside as of course this would be a bit silly. Boom. 
So I was wondering, since the sintered disc has all these air pockets that maybe it could have gradually been filling up with gunk, plasticiser or gooey propane smell additive ? This thought is again conjecture.

Ooo I love a good mystery me! 

But I realise it's a pain for you Sal. I hope you get sorted soon, and please let us know what it really is.

[silverlemon]

(even though presumably the flash back arrestor would prevent back flow?)

Sal

Just seen this bit. I don't believe the flashback arrestors prevent back flow, you would need a non return valve for that (a one way valve). What the flashback arrestor does is to allow the gas to pass through freely in either direction through the sintered disc which provides a physical barrier for any stray flame trying to pass through it. ie gas can pass through but flames can't. Just looked on Wikipedia and they reckon that the sintered disc takes the heat out of the flame so it's not hot enough to ignite the gas. You gotta love that site! 

Which leads me on to say that if we are to protect our hoses from flashback in addition to our gas cylinders then we really should be installing our flashbacks just behind the torch and not next to the regulator. But of course there is the whole debate about whether you need a flashback with a surface mix torch anyway....but that's another issue. lol

Sorry this post is a bit geeky, I did say it wasn't just Dickie!

[ejralph]

What scares me most about this is that Sal is a physicist. If she don't know what this is, then we are all doomed. Doomed I tell ya.

Whose torch will die next? Who will get got by goo?

Emma  

[ejralph]

Talking of which, where IS Sal?

Do you think she blew up overnight? 

Hope not. 

Emma