LPG tank cleaning

[dom14]

Hey guys,
Do the LPG tanks need cleaning after a long time use?
I mean, can the sludge build up inside the tank?
If it's a good thing to clean them, what do we use to flush inside of the tank?
Opening the tank and scrub inside with petrol,etc??!!
I'm about to flush the plumbing of the LPG lines.
So, I thought since I'll be dropping the tank under the chassis, I might give it a clean as well(if its a good thing).
There won't be any gas in the tank when I drop it.
Thanks

[jack]

Hi dom14,
Don't know about sludge but here in Vic they need to be tested and recertification every ten years. I had one done a few years ago and only needed pressure testing, there was no comment about cleaning.

[garett]

nope never needed to clean a lpg tank.. change parts on it repaint it seen that done but never cleaned one. the sludge / oil drops out of the lpg when it changes state. so i dont think it would even get dirty.

[dom14]

Hi dom14,
Don't know about sludge but here in Vic they need to be tested and recertification every ten years. I had one done a few years ago and only needed pressure testing, there was no comment about cleaning.

Yes, I had one of the tanks retested, the other needs it done soon as well.
I'm wondering about all these stories that says how dirty LPG is, etc etc.
So, I thought some of gunk can end up in the bottom of the tank.

[dom14]

nope never needed to clean a lpg tank.. change parts on it repaint it seen that done but never cleaned one. the sludge / oil drops out of the lpg when it changes state. so i dont think it would even get dirty.

Hi mate,
Where does the sluge/oil end up when it changes from liquid to gas?
Is it necessary to flush the LPG plumbing between the tanks and the converter?
Do the LPG lock off valve come with a filter inside it by default?
Do they need replacing after few years of use?
The reason is that I've seen gunk build up inside the LPG converter.]
I wondered where they come from.
Thanx

[garett]

it drops in the converter. the lock off usually has a filter but thats for particles in the liquid gas. i would clean the converter and check the filter just be careful of the seals when you put it back. think of it like an air filter. carby cleaner works a treat. while its apart make sure the plungers can move freely but dont oil/grease them.

[4bye4]

Hi mate,
Where does the sluge/oil end up when it changes from liquid to gas?
Is it necessary to flush the LPG plumbing between the tanks and the converter?
Do the LPG lock off valve come with a filter inside it by default?
Do they need replacing after few years of use?
The reason is that I've seen gunk build up inside the LPG converter.]
I wondered where they come from.
Thanx

Hi Dom - I agree with Garett. Gasoil if it condenses does so in the converter/regulator and not in the tank. Yes tanks have to be checked every 10 years in all states I think. I do hold a gas fitters licence here in WA BTW. LPG isn't dirty BTW, one of its issues is that it is too clean. There is no oil or liquids in the gas to help cool and lubricate the engine. This isn't an issue with car motors but I work on air cooled LPG motors and we need all the cool we can get.

[Bigcol]

Dom,
as it suggests LPG (Liquified Petroleum Gas) so when you fill the tank, it is in a liquid state - and bloody cold as well - freeze your fingers off if you are not careful
it stays liquid all the way to the converter
which, does as its name suggests - converts the Liquid to a gas
then pumps it through to your carby - EFI - whatever as a gas

the "sludge" in your converter is WAX
they put the wax into the LPG to stop it freezing completely
depending on the time of the year, depends on how much wax is in it
summer time, very little - winter time a lot more - hence the reason I used to get my GQ tuned in September and in April - when they change the Gas/Wax mix

your tank will have very little if any dirt / rust / swarf / anything in it
so apart from cleaning the outside, and repainting in Silver
there is not a lot that needs to be done to it

as Tony said, it is very clean, and tends to dry out seals and gaskets in Carbi's etc
if you have a "Flash Lube" canister on the engine - sewing machine oil is just as good as any of the other brands on the market
the flash lube drops 1 drop of oil into your gas line / carbi line at a set amount to help lubricate the upper cylinder

cheers

[dom14]

Dom,

as Tony said, it is very clean, and tends to dry out seals and gaskets in Carbi's etc
if you have a "Flash Lube" canister on the engine - sewing machine oil is just as good as any of the other brands on the market
the flash lube drops 1 drop of oil into your gas line / carbi line at a set amount to help lubricate the upper cylinder

cheers

Hi BigCol,
I haven't been aware of flash lube canister before.
I will try to find bit more about it and how it works.
I drive on petrol for few minutes everyday to allow some carby lubrication of the inner carby parts.
But, I'm bit confused when you say they put wax into it.
I know the characteristic oniony smell of the LPG is from Ethanethiol which is colourless gas and I reckon it can't be a contributor to the gunk.

LPG freezing point is -144c. So, I'm not sure why they put wax in it.
Can you please tell me bit more about that wax?
Why doesn't some of this wax end up sticking to the inside/bottom of the tank?

Then again I had a first hand experience of the refrigeration effect of the hissing LPG from an LPG tank which turned the tank inside temperature into sub zero in open atmosphere.
I loosened the service valve and allowed the little bit of LPG that was already in the tank to evapourate into the atmosphere.
I opened up the service valve plate, thinking the little bit LPG has already completely hissed out(shouldn't have done that anyway). Luckily I was wearing goggles, rubber gloves+work goves on top of it(I take no chances). I saw the few litres of liquid LPG inside the tank. It couldn't have been Ethanethiol, 'cos that was way too much liquid gas there. Ethanethiol would've been deadly toxic in that volume. I couldn't feel the refrigeration effect when touching the outside of the tank while the gas was hissing out 'cos I was wearing double gloves, yet I still felt the some cold when I was rolling the tank. I didn't even expect even in my wildest dreams to see liquid gas in hot summer day. The temperature inside the tank obviously still was below -44c due the hissing LPG refrigeration effect. I had to tip the LPG liquid inside the tank on to the ground to make sure it was LPG. It boiled and evapourated in no time. I shouldn't have vented even a little bit LPG like that into the atmosphere, but I learnt a valuable lesson not to assume I know a lot about LPG behaviour. What I should've done was to attach that tank as my aux tank and use that LPG first.
I didnt wanna do that at that time 'cos I picked up the tank from the side of the road with some gas in it(I thought there could've been too much gunk inside the tank). Somebody dumped it as hard rubbish.

Do they add wax into LPG 'cos of that refrigeration effect can freeze the LPG inside plumbing just before the LPG converter?

If hissing(sudden change from liquid to gas) happens inside the converter, then it's possible the liquid gas before that can freeze. That must be the reason for having hot water line into the converter. But, obviously not much use until the engine warms up enough.

[dom14]

Hi Dom - I agree with Garett. Gasoil if it condenses does so in the converter/regulator and not in the tank. Yes tanks have to be checked every 10 years in all states I think. I do hold a gas fitters licence here in WA BTW. LPG isn't dirty BTW, one of its issues is that it is too clean. There is no oil or liquids in the gas to help cool and lubricate the engine. This isn't an issue with car motors but I work on air cooled LPG motors and we need all the cool we can get.

Hi mate,
Do you think it's a waste of time for me to attempt to flush the LPG plumbing with pressurized air, 'cos there won't be any gunk inside the plumbing or the lock off valve filter?
Thanx

[dom14]

it drops in the converter. the lock off usually has a filter but thats for particles in the liquid gas. i would clean the converter and check the filter just be careful of the seals when you put it back. think of it like an air filter. carby cleaner works a treat. while its apart make sure the plungers can move freely but dont oil/grease them.

Thanx Garett. I'm yet to finish the rebuilding of the converter with a kit. So, this is really useful stuff.
Cheers
Dom

P.S. My replacement dizzy is going pretty well. It hasnt got the same grunt as the original one, but no hiccups, backfires or misfires. I still haven't changed the ignition leads. I decided to get a set of AMRgas LPG leads(Gasmaster Ignition Leads). With two dizzys in my arsenal, now I can pull a one apart and learn to fine tune it for my needs. I'm also experimenting with carby-manifold spacers of different thickness. The idea is to get a bit more grunt. :)

[Bigcol]

Hi BigCol,

Then again I had a first hand experience of the refrigeration effect of the hissing LPG from an LPG tank which turned the tank inside temperature into sub zero in open atmosphere.
I loosened the service valve and allowed the little bit of LPG that was already in the tank to evapourate into the atmosphere.
I opened up the service valve plate, thinking the little bit LPG has already completely hissed out(shouldn't have done that anyway). Luckily I was wearing goggles, rubber gloves+work goves on top of it(I take no chances). I saw the few litres of liquid LPG inside the tank. It couldn't have been Ethanethiol, 'cos that was way too much liquid gas there. Ethanethiol would've been deadly toxic in that volume. I couldn't feel the refrigeration effect when touching the outside of the tank while the gas was hissing out 'cos I was wearing double gloves, yet I still felt the some cold when I was rolling the tank. I didn't even expect even in my wildest dreams to see liquid gas in hot summer day. The temperature inside the tank obviously still was below -44c due the hissing LPG refrigeration effect. I had to tip the LPG liquid inside the tank on to the ground to make sure it was LPG. It boiled and evapourated in no time. I shouldn't have vented even a little bit LPG like that into the atmosphere, but I learnt a valuable lesson not to assume I know a lot about LPG behaviour. What I should've done was to attach that tank as my aux tank and use that LPG first.
I didnt wanna do that at that time 'cos I picked up the tank from the side of the road with some gas in it(I thought there could've been too much gunk inside the tank). Somebody dumped it as hard rubbish.



YOU SIR, need to go buy a Lotto Ticket

you are Damn lucky you didnt kill yourself or someone else

LPG is NOT something to be pissing around with if you dont even know what it is.............

1 spark - just 1 spark
static electricity off you clothes, dropping a spanner on the ground, over cast weather static charge
ANY of these, and you would have been the "Late" Dom

[Bigcol]

I understand the want to learn how to do things with your car - no problemo mate - easy as, we can all help some way

but

for the Love of Apples - dont play with gas
I have a mate who was (WAS) a gas fitter - he has 3rd degree burns to his hands because of static electricity while playing with gas


mate, you dont know just how lucky you are

[Bigcol]

Hi BigCol,
I haven't been aware of flash lube canister before.
I will try to find bit more about it and how it works.
I drive on petrol for few minutes everyday to allow some carby lubrication of the inner carby parts.
But, I'm bit confused when you say they put wax into it.
I know the characteristic oniony smell of the LPG is from Ethanethiol which is colourless gas and I reckon it can't be a contributor to the gunk.

LPG freezing point is -144c. So, I'm not sure why they put wax in it.
Can you please tell me bit more about that wax?
Why doesn't some of this wax end up sticking to the inside/bottom of the tank?

Do they add wax into LPG 'cos of that refrigeration effect can freeze the LPG inside plumbing just before the LPG converter?

If hissing(sudden change from liquid to gas) happens inside the converter, then it's possible the liquid gas before that can freeze. That must be the reason for having hot water line into the converter. But, obviously not much use until the engine warms up enough.

Im not sure of all of the additives they put in

I know of the wax, because I stripped an Empco converter to see how it works - and found heaps of wax, so I asked why.........? - its there to help lubricate the gas lines - very minimal amount though - after 10 years, I had less than 1/2 a teaspoon all up from the whole unit

I do know here in WA they have a "Summer mix" and a "Winter mix"

my GQ was tuned for performance on Gas - so it was very noticeable when they changed the mix

[4bye4]

Hi Dom - a couple of things;
First I agree with Big Col and others on this forum Don't mess with gas. Whin I said I was a licensed gas fitter it wasn't just to brag.
Second The reason there was still LPG in the tank after you opened the service valve was probably because the service valve has a check valve in it to stop the gas flooding out in the event of the gas line to the engine being cut say in a crash. If the flow reaches a certain"speed" it shuts off.
Third If you are going to play with the gas setup on your vehicle it's probably not a good idea to put it up on the internet, your not supposed to. Not in WA anyway.
Fourth LPG in Australia is a mixture of Butane and Propane gasses. One burns fast and hot and the other slower and cooler. They are mixed to give an even burn and power rate. This statement is really simple, it would take a few pages to actually describe why the two gasses are used.
Fifth, The liquid changes from liquid to gas in the converter/regulator and as it does so it cools the converter/regulator. The radiator water is circulated through the converter/regulator to stop the iner valve from freezing. Incidently, if you are still freezing the converter/regulator or the surrounding pipes, you probably have one or more cylinders down. It means that you are drawing a lot of gas which means that some of the gas may be going traight out the exhaust.
Last Be aware that LPG is heavier than air and if you vent it or have a leak it can collect in low points on your floor, the same as petrol will. The BIG difference is that you can see petrol collecting in puddles but you can't see LPG.
Nuff from me, and your question to me about air flushing the lines? Don't bother you have already flushed them with LPG. If there is wax or oil in the system it will be in the regulator, not the lines. Not a good idea to introduce compressor air into a gas line anyway as there may be traces of oil from the compressor in the air.

[threedogs]

@ Dom dont attempt to open the tank and clean it , leave it to the gas ppl
They have all the gear to do it safely, plus its illegal I think

[dom14]

@ Dom dont attempt to open the tank and clean it , leave it to the gas ppl
They have all the gear to do it safely, plus its illegal I think

Of course mate. It's not legal. Touching any part of the LPG system is illegal.
We have to take educated judgements on how far we go 'fiddling' with LPG without getting cooked.
In most cases, it's better to leave it with a licensed LPG techie as they go through enough education and get to see enough dramas to know what they are doing.`
Besides, you guys here have already explained it's a waste of time for me to attempt to clean the inside of an LPG tank. :)
Personally, I don't fiddle with LPG until I listen to lot of opinions and do lot of reading about it. Even when I opened the tank back then, I talked to a few and got few opinions about it, as well as reading enough about it. But, did not expect to see liquid LPG inside the tank, when I fully opened the service plate. I wasn't warned about it, but learnt it myself by playing with fire.

In Victoria, the law is a little bit less strict than in WA. Most of the LPG blueprints were developed in WA, so it makes sense the law is more strict there.
For example, adding an auxiliary tank doesn't need any stamping in Victoria.
Which means there's no indication on the plumbing or the tank that it's done professionally.
In other words, if you know how to do it safely and properly, you can add an auxiliary tank yourself and there won't be any issues as far as law concerns. I think this is not the case in WA and Queensland. Not too sure abouth other states.

[dom14]

Thanks guys. I was aware the LPG is heavier than the air and stay near the ground for a while. So, I purposely picked a sunny, moderately windy day to vent out the little bit of LPG in the tank. I also got the 'inspiration' to do it from the guy who sold and retested the auxiliary tank to me, who advised me not to do that, but he himself did it that once, outside his warehouse with one of his older tanks. So, I thought I could manage little bit gas into the air without causing a major explosion. That was a one time thing. There's no chance i would do that again. I know better now. I picked up that tank on the side of the road, and it was in perfect condition(from the outside looks). The tank the tester sold me was in date, but had a noise gauge floater which was annoying the crap out of me, 'cos of it was hitting the tank when there's gas inside it(The aux tank was inside the vehicle).
I wanted to use the floater of the tank I found on the side of the road to minimize that noise(the floater of tank I found on the side of the road was plastic, where as mine it was metal, hence the annoying noise when it hits inside the tank). That's the reason I opened the service plate of the tank, otherwise I wouldn't have bothered to open it, let alone picking it up from the side of the road rubbish.
I did the swap successfully and swapped floater stopped the noise of my auxiliary tank. The gauge on the tank was accurate as well.

I know, I've been warned here about the static electricity charges as well, which I've been aware but didn't think it would cause big problems back then, with the precautions I took.
I've seen a commuter filling up his car at the servo and accidentally sparking the petrol from his long sleeve shirt and starting a fire.
In my experience with working at servos, I've seen petrol catching fire, but haven't seen any LPG dramas yet. That's probably 'cos extra precautions we take with LPG and the strict law prevents many dramas from happening.

[dom14]

Second The reason there was still LPG in the tank after you opened the service valve was probably because the service valve has a check valve in it to stop the gas flooding out in the event of the gas line to the engine being cut say in a crash. If the flow reaches a certain"speed" it shuts off.
Third If you are going to play with the gas setup on your vehicle it's probably not a good idea to put it up on the internet, your not supposed to. Not in WA anyway.


Thanx mate. Yes, I do understand I'm not suppose to put these stuff on the internet. But, the idea was to warn anybody else who might try that, and may end up not getting as lucky as myself and end up having serious cold burns. Having some basic professional training on working with LPG at service stations, I know LPG is something you don't mess unless you know all about it's behaviour. The above venting was done in open flat area with nobody or a building near the tank.

About the above incident,
Don't you think it should've vented out to the atmosphere completely when I started opening the service plate? I did talk to a tank tester before I did that to make sure I don't miss anything, but I obviously missed one thing even experienced guy couldn't warn me about. Isn't it slightly amazing some of the liquid LPG was still inside an opened tank? Only way I can think of LPG stay as a liquid is
either,
1)pressure
2)very low sub zero temperature.
Since the pressure wasn't there anymore with the interior of the tank completely open to the atmosphere, it must have been the very low temperature inside the tank at that time.
And that low temperature must have got there from the hissing refrigeration effect(high to low pressure change from a small opening, just the way it happens in A/C systems)

Am I right?!

[4bye4]

Of course mate. It's not legal. Touching any part of the LPG system is illegal.
We have to take educated judgements on how far we go 'fiddling' with LPG without getting cooked.
In most cases, it's better to leave it with a licensed LPG techie as they go through enough education and get to see enough dramas to know what they are doing.`
Besides, you guys here have already explained it's a waste of time for me to attempt to clean the inside of an LPG tank. :)
Personally, I don't fiddle with LPG until I listen to lot of opinions and do lot of reading about it. Even when I opened the tank back then, I talked to a few and got few opinions about it, as well as reading enough about it. But, did not expect to see liquid LPG inside the tank, when I fully opened the service plate. I wasn't warned about it, but learnt it myself by playing with fire.

In Victoria, the law is a little bit less strict than in WA. Most of the LPG blueprints were developed in WA, so it makes sense the law is more strict there.
For example, adding an auxiliary tank doesn't need any stamping in Victoria.
Which means there's no indication on the plumbing or the tank that it's done professionally.
In other words, if you know how to do it safely and properly, you can add an auxiliary tank yourself and there won't be any issues as far as law concerns. I think this is not the case in WA and Queensland. Not too sure abouth other states.

Not sure Dom. But I suspect it was boiling off and you couldn't see it. If you left it long enough it would have evaporated.

[dom14]

Not sure Dom. But I suspect it was boiling off and you couldn't see it. If you left it long enough it would have evaporated.

Nope. It was a liquid and yes of course it was boiling off as I was tipping the liquid LPG onto the ground as I was rolling the tank.
But, for the sake of the safety, it's bad news to find liquid LPG in an open tank, even though it evaporated pretty quickly.
The tipping liquid LPG could've burnt the crap out of my feet if I wasn't wearing safety boots(who else would be wearing safety cap boots at home? Now you know I"m indeed a safety conscious nut. :D)
Liquid CO2, Nitrogen, etc are fine. They can give a horrific cold burn just the same way as LPG, except LPG has the added danger of serious and easy flammability.
Neither the LPG fitter or the tank tester warned me about it, even though they gave me all the information about how to safely let the LPG out of a tank,
while also advising me not to do that in a congested area.
I think these are the reasons for the existence of some strict laws on LPG handling these days.
And I also think I experienced the seemingly weird thing, 'cos I went to the length of venting LPG off a tank into the air & then opening the tank, something average bloke won't do. :)
And also went to the length of describing it here, another thing an average bloke wont' dare to do here. :D
We think we know all about it, but that's not the case. And definitely not the case for backyard techie 'fiddlers' like myself.
Cheers
Dom

[Bigcol]

I think it was still venting off, when you removed the service plate

otherwise it would have still been hissing out of the open line...................

you probably opened it without realizing it was still venting - hence the Liquid still in the tank

as 4Bye was saying, it would have been boiling off still

I know years ago, I got a second hand tank as I was going to fit a "reserve" gas tank - and I opened the valve, and it took 2 days before it was completely empty
never ended up using it either.........

[dom14]

I think it was still venting off, when you removed the service plate

otherwise it would have still been hissing out of the open line...................

you probably opened it without realizing it was still venting - hence the Liquid still in the tank

as 4Bye was saying, it would have been boiling off still

I know years ago, I got a second hand tank as I was going to fit a "reserve" gas tank - and I opened the valve, and it took 2 days before it was completely empty
never ended up using it either.........

Yes, but I got confused 'cos of my understanding of LPG behaviour was that
to stay as a liquid there has to be either
1)high pressure or
2)very low temperature(below -44c)

Of course, both above reasons are essentially the same thing, which is low temperature. The pressurized LPG gas turns into the liquid LPG by absorbing the energy from pressure and dropping the temperature below -44c.

So, once the hissing was over, I assumed all the liquid LPG inside the tank had vented out.
After all,.. that's what exactly happens when we empty the tank by using all the LPG to run the engine, right?
It doesn't necessarily get assisted by the engine vacuum to empty the LPG in the tank, does it?
The pressure of the LPG inside the tank is enough to empty itself(I think).

In my way of trying to understand it in terms of (Physics), I tend to think the few litres of LPG is still their in liquid form when I opened the service plate, 'cos the temperature inside the tank(or the area the little bit of LPG liquid was at the bottom) was sub zero.
Basically, inside the tank was still a fridge(freezer rather) 'cos I inadvertently created a freezer through my illegal venting of the gas by loosening the valve.(Yes, it was hissing for a good half hour through the minute opening quite violently, which is exactly what happens with the A/Cs and fridges.

Even if I put the physics aside, in common sense, you would still expect the tank to be empty when you hear no more hissing when opening the service plate, wouldn't you?
Or may be you guys would expect to see some liquid LPG in there! I might be the one with the shortage of common sense here, 'cos I filled my head with useless physics.

Unless there's sub zero temperature inside the tank(the pressure was already gone), the LPG couldn't have possibly stayed inside the tank as a liquid.( Ok, I admit the common sense has turned into physics again. :) )

Remember our secondary school experiments with dry ice(solid CO2) & liquid nitrogen?!

We get liquid nitrogen or dry ice out of a freezer which is cold enough to turn CO2 into solid and nitrogen into a liquid. Then we put it into a thermos to preserve it's state. Thermos becomes a freezer and keeps the liquid nitrogen as liquid(pressure & the vacuum flask). When we open the lid, it's still a liquid, 'cos the thermos has turned into a freezer, cos the thermos(vacuum flask) won't allow the heat to pass through that easily via the vacuum). That allows us to pour liquid nitrogen onto things in room temparaure(the lab experiments we did at secondary school) to freeze dry the stuff.

For example, if I let the LPG to violently gush out by allowing it through solenoid valve, then I wouldn't have any liquid LPG(or gas for that matter) left inside when I open the service plate.
So, remember I let the LPG to vent out by slightly undoing the service plate(not actually letting it gush out via the solenoid valve). So, it was hissing at high speed through a minute opening, exactly as it happens in A/Cs. This was how I understood what happened there. But, all the physics I knew, didn't prepare me for the potentially dangerous hazard. I didn't think there was any fire hazard there 'cos I took all the known precautions(except the static electricity of the air around me). The real hazard was a pretty bad cold burns, not realizing there was liquid gas in there. That was really stupid of me. Knowing physics is one thing. Not remembering a damn thing to have any use in real life is another thing.
I think somebody once said, Knowledge is not power, it's potential power.
In other words, knowledge is useless until you use it for practical purposes.
Like most of the math we learn at school. All the secondary school math is useless for everyday stuff, except the most simple operations like adding, dividing, multiplying and subtracting, which is the preschool stuff. :D
Unless we are planning to become math teachers, engineers, mathematicians etc, we only need to know the basic math operations. The rest was simply a waste of time. Calculus, statistics and other secondary school math crap were useless for any everyday stuff. :offtopic::oops: