Hi all

Does anyone know if there's a cheaper way of setting up an Oxy/
Acetylene welding/brazing kit, than hiring bottles from BOC.

I have the rest of the kit - burners, goggles, regulators, hoses, anti-
flashback units, etc, etc - from the last time may late Dad and I did
serious gas welding (circa 16 years ago).  Back then, the bottles were
circa £90.00 in hire charges  £9.00 for each gas refill  delivery
and handling.  A little too expensive for the occasional Model
Engineering use I need now.  Trouble is, when you need Oxy/Acetylene
nothing else will substitute (I have Propane/Air torches and the "self-
blowing" Sievert kit).

What's really needed is some supply of the Oxy/Acet bottles on the
same basis as Calor Gas bottles - ie Pay a once only charge when
"signing up" and then just for the gas refills after that.

It's a long-shot I guess - BOC do like their Monopoly - but, if anyone
knows, it'll probably be one of the guys in this group.

Regards
Andy

"houstonceng"  wrote

I have the rest of the kit - burners, goggles, regulators, hoses, anti-
flashback units, etc, etc - from the last time may late Dad and I did
serious gas welding (circa 16 years ago).  Back then, the bottles were
circa £90.00 in hire charges + £9.00 for each gas refill + delivery
and handling.

You'd better sit down and get a stiff drink.


I have a size J acetylene and size T oxygen.

Last refills about 2 months ago were GBP 56 for the acetylene and a mere GBP 
15 for the oxygen.

There was a charge of GBP 10 for the transaction (I think this is the same 
irrespective the number of cylinders exchanged).

Rental, if I recall from the last invoice, was about GBP 90 per year for the 
pair of cylinders.

houstonceng wrote:
> Hi all
> 
> Does anyone know if there's a cheaper way of setting up an Oxy/
> Acetylene welding/brazing kit, than hiring bottles from BOC.
> 
> I have the rest of the kit - burners, goggles, regulators, hoses, anti-
> flashback units, etc, etc - from the last time may late Dad and I did
> serious gas welding (circa 16 years ago).  Back then, the bottles were
> circa £90.00 in hire charges + £9.00 for each gas refill + delivery
> and handling.  A little too expensive for the occasional Model
> Engineering use I need now.  Trouble is, when you need Oxy/Acetylene
> nothing else will substitute (I have Propane/Air torches and the "self-
> blowing" Sievert kit).
> 
> What's really needed is some supply of the Oxy/Acet bottles on the
> same basis as Calor Gas bottles - ie Pay a once only charge when
> "signing up" and then just for the gas refills after that.
> 
> It's a long-shot I guess - BOC do like their Monopoly - but, if anyone
> knows, it'll probably be one of the guys in this group.
> 
> Regards
> Andy


I don't know whether it's any help, but I use a 5 l/min oxygen 
concentrator with MAPP gas for small stuff. Cost £200-odd second-hand 
from fleabay, wait around a bit and you may find one at about that price.

Oxy/MAPP is of course not as good as oxy/acetylene, and it won't power 
big torches, but it works ok for welding up to 1/8" steel, and with 
preheating and an extra air/gas torch it will braze 1/4" + steel. I 
don't need to weld bigger stuff, so it was a good solution for me, but ymmv.



The MAPP gas cylinders seem to last a reasonable time, but disposable 
oxygen cylinders don't :( and they are very expensive unless you are 
doing occasional micro-work.

Disposable oxygen cylinders are however 3 or 4 times better now than 
they were some years ago, giving maybe 20 minutes in a nozzle suitable 
for brazing 1/8 steel. Only cost-effective if you only do very 
occasional work, however you might want to give them a try - they're not 
for me though.



I've often thought of building a small compressor to fill bottles from 
the concentrator, but high pressure oxygen is BL**DY DANGEROUS (far more 
so than liquid oxygen) and I haven't tried.

You can get a professionally made pump for the purpose, but at a price 
(ouch!) and you'll probably have to buy a new, expensive model, 
concentrator with it..



Another often-mentioned low-capital source of oxygen is water 
electrolysis, but a professionally-made outfit will cost mega$$'s, they 
are not particularly cheap to run, and they are only really suitable for 
  very small torches.




I don't know of any cheap small-scale sources of acetylene, much as I'd 
like to - while oxy/MAPP welding is quite possible, it's nowhere near as 
easy as oxy/acetylene (though oxy/MAPP is fine for brazing).


-- Peter Fairbrother

houstonceng wrote:
> Hi all
> 
> Does anyone know if there's a cheaper way of setting up an Oxy/
> Acetylene welding/brazing kit, than hiring bottles from BOC.
> 
> I have the rest of the kit - burners, goggles, regulators, hoses, anti-
> flashback units, etc, etc - from the last time may late Dad and I did
> serious gas welding (circa 16 years ago).  Back then, the bottles were
> circa £90.00 in hire charges + £9.00 for each gas refill + delivery
> and handling.  A little too expensive for the occasional Model
> Engineering use I need now.  Trouble is, when you need Oxy/Acetylene
> nothing else will substitute (I have Propane/Air torches and the "self-
> blowing" Sievert kit).
> 
> What's really needed is some supply of the Oxy/Acet bottles on the
> same basis as Calor Gas bottles - ie Pay a once only charge when
> "signing up" and then just for the gas refills after that.
> 
> It's a long-shot I guess - BOC do like their Monopoly - but, if anyone
> knows, it'll probably be one of the guys in this group.
> 
> Regards
> Andy

I needed a supply of Argon and found that Energas 
(http://www.energas.co.uk/) was rather more reasonable than BOC.

YMMV.

-- 
Regards, Gary Wooding
(To reply by email, change feet to foot in my address)

"John" <John@invalid.invalid> wrote in message 
news:g9c6jt$278$1@registered.motzarella.org...
>
> "houstonceng"  wrote
>
> I have the rest of the kit - burners, goggles, regulators, hoses, anti-
> flashback units, etc, etc - from the last time may late Dad and I did
> serious gas welding (circa 16 years ago).  Back then, the bottles were
> circa £90.00 in hire charges + £9.00 for each gas refill + delivery
> and handling.
>
> You'd better sit down and get a stiff drink.
>
>
> I have a size J acetylene and size T oxygen.
>
> Last refills about 2 months ago were GBP 56 for the acetylene and a mere 
> GBP 15 for the oxygen.
>
> There was a charge of GBP 10 for the transaction (I think this is the same 
> irrespective the number of cylinders exchanged).
>
> Rental, if I recall from the last invoice, was about GBP 90 per year for 
> the pair of cylinders.
>
>
>

I have the current price list for BOC as I would like to have oxy/act set up 
again, but certainly not at their prices.  I used to swap my bottles at work 
and just pay for the gas but I haven't worked there for many years.
These prices are for full sized bottles (W = Oxygen, H = Acetylene);
Monthly Rental: Oxy = £ 8.11,   Act = £ 10.40
Annual Rental:   Oxy = £ 92.47,   Act = £ 118.62
If using Annual Rental, a full years rental is due BEFORE initial supply !!
Gas:  Oxy = £ 19.96,   Act = £ 77.44
If not paying by Direct Debit an Advanced Payment of £ 75 is required.
Delivery = £ 38.19 inc VAT irrespective of number of bottles.
Collection = £ 12.63 inc VAT irrespective of number of bottles.
Soo, try and work that lot out .... no wonder a lot of companies have turn 
away from BOC and Oxy/Act.  Most scrapyards for example are now using 
Oxy/Propane from other suppliers.
I could give you prices of 'portapack' (small bottles of oxy/act) if you 
like but they will still be expensive considering all the different charges 
that BOC add on.
Hope this is of use to you all.
Cheers
Brad

On or around Sat, 30 Aug 2008 10:38:29 -0700 (PDT), houstonceng
 enlightened us thusly:

>Hi all
>
>Does anyone know if there's a cheaper way of setting up an Oxy/
>Acetylene welding/brazing kit, than hiring bottles from BOC.
>

I rent 'em from Air Products.  not exactly cheap, still, but a lot less than
BOC
-- 
Austin Shackles.  www.ddol-las.net  my opinions are just that
Travel The Galaxy!  Meet Fascinating Life Forms...
------------------------------------------------\   
   >>  http://www.schlockmercenary.com/  <<      \  ...and Kill them.
a webcartoon by Howard Tayler; I like it, maybe you will too!

"BRAD"  wrote
>
> I have the current price list for BOC as I would like to have oxy/act set 
> up again, but certainly not at their prices.  I used to swap my bottles at 
> work and just pay for the gas but I haven't worked there for many years.
> These prices are for full sized bottles (W = Oxygen, H = Acetylene);
> Monthly Rental: Oxy = £ 8.11,   Act = £ 10.40
> Annual Rental:   Oxy = £ 92.47,   Act = £ 118.62
> If using Annual Rental, a full years rental is due BEFORE initial supply 
> !!
> Gas:  Oxy = £ 19.96,   Act = £ 77.44
> If not paying by Direct Debit an Advanced Payment of £ 75 is required.
> Delivery = £ 38.19 inc VAT irrespective of number of bottles.
> Collection = £ 12.63 inc VAT irrespective of number of bottles.
> Soo, try and work that lot out .... no wonder a lot of companies have turn 
> away from BOC and Oxy/Act.  Most scrapyards for example are now using 
> Oxy/Propane from other suppliers.
> I could give you prices of 'portapack' (small bottles of oxy/act) if you 
> like but they will still be expensive considering all the different 
> charges that BOC add on.
> Hope this is of use to you all.
> Cheers
> Brad


Interesting. I've never seen a published BOC price list and assumed there 
are different pricing structures depending upon the user and annual usage.

I'm relatively lucky in having a good BOC stockist locally, and by taking 
the cylinders to the agent I avoid the delivery/collection charges.

"Austin Shackles"  wrote

>>
>>Does anyone know if there's a cheaper way of setting up an Oxy/
>>Acetylene welding/brazing kit, than hiring bottles from BOC.
>>
>
> I rent 'em from Air Products.  not exactly cheap, still, but a lot less 
> than
> BOC


Do you have any prices for Air Products?

John wrote:

> I'm relatively lucky in having a good BOC stockist locally, and by taking 
> the cylinders to the agent I avoid the delivery/collection charges. 

Then you are lucky if they don't charge it.   Mine makes that charge 
even If 9which is always) I take the bottle back myself.


Wayne....
> 
>

"John" <John@invalid.invalid> wrote in message 
news:g9e9m9$6ms$1@registered.motzarella.org...
>
> "BRAD"  wrote
>>
>> I have the current price list for BOC as I would like to have oxy/act set 
>> up again, but certainly not at their prices.  I used to swap my bottles 
>> at work and just pay for the gas but I haven't worked there for many 
>> years.
>> These prices are for full sized bottles (W = Oxygen, H = Acetylene);
>> Monthly Rental: Oxy = £ 8.11,   Act = £ 10.40
>> Annual Rental:   Oxy = £ 92.47,   Act = £ 118.62
>> If using Annual Rental, a full years rental is due BEFORE initial supply 
>> !!
>> Gas:  Oxy = £ 19.96,   Act = £ 77.44
>> If not paying by Direct Debit an Advanced Payment of £ 75 is required.
>> Delivery = £ 38.19 inc VAT irrespective of number of bottles.
>> Collection = £ 12.63 inc VAT irrespective of number of bottles.
>> Soo, try and work that lot out .... no wonder a lot of companies have 
>> turn away from BOC and Oxy/Act.  Most scrapyards for example are now 
>> using Oxy/Propane from other suppliers.
>> I could give you prices of 'portapack' (small bottles of oxy/act) if you 
>> like but they will still be expensive considering all the different 
>> charges that BOC add on.
>> Hope this is of use to you all.
>> Cheers
>> Brad
>
>
> Interesting. I've never seen a published BOC price list and assumed there 
> are different pricing structures depending upon the user and annual usage.
>
> I'm relatively lucky in having a good BOC stockist locally, and by taking 
> the cylinders to the agent I avoid the delivery/collection charges.

There is a published price list that lists the rental charges, along with 
the refill charges.

They have started doing the 3 and 5 year rentals again, which saves a good 
amount of money on rental charges.

"Wayne Weedon"  wrote

>
>> I'm relatively lucky in having a good BOC stockist locally, and by taking 
>> the cylinders to the agent I avoid the delivery/collection charges.
>
> Then you are lucky if they don't charge it.   Mine makes that charge even 
> If 9which is always) I take the bottle back myself.


All I get charged is a flat GBP10 processing charge by returning the 
cylinders to the agent.

I wrote:

> I don't know of any cheap small-scale sources of acetylene, much as I'd 
> like to - while oxy/MAPP welding is quite possible, it's nowhere near as 
> easy as oxy/acetylene (though oxy/MAPP is fine for brazing).


Come to think of it, you could make acetylene from carbide.

3 kg of carbide, producing 1.1 cu m of acetylene, costs £20.75, about 
£19 per cubic meter: if a H size cylinder costs £77 to refill, that's 
about £10 per cubic meter of useable acetylene,

So acetylene from carbide costs around twice as much as acetylene in a 
big cylinder - and no rental, more reasonable delivery fees, no return 
fees, and available in small quantities.



The problem then is the generator to produce the acetylene. Small 
capacity generators are available at around £40-50, but I do mean small. 
Apparently you can get bigger generators for welding for third-world 
use, but I don't know where from.


Making your own generator? Could be inexpensive, but I don't advise it 
unless you know what you are doing, and thoroughly understand the 
dangers (for instance it can explode all by itself, unlike propane etc., 
it has wider flammability limits in air than propane, lower flash point, 
and more) of acetylene.


-- Peter Fairbrother

On Aug 31, 4:34 pm, Peter Fairbrother  wrote:
> I wrote:
> > I don't know of any cheap small-scale sources of acetylene, much as I'd
> > like to - while oxy/MAPP welding is quite possible, it's nowhere near as
> > easy as oxy/acetylene (though oxy/MAPP is fine for brazing).
>
> Come to think of it, you could make acetylene from carbide.
>
> 3 kg of carbide, producing 1.1 cu m of acetylene, costs £20.75, about
> £19 per cubic meter: if a H size cylinder costs £77 to refill, that's
> about £10 per cubic meter of useable acetylene,
>
> So acetylene from carbide costs around twice as much as acetylene in a
> big cylinder - and no rental, more reasonable delivery fees, no return
> fees, and available in small quantities.
>
> The problem then is the generator to produce the acetylene. Small
> capacity generators are available at around £40-50, but I do mean small> Apparently you can get bigger generators for welding for third-world
> use, but I don't know where from.
>
> Making your own generator? Could be inexpensive, but I don't advise it
> unless you know what you are doing, and thoroughly understand the
> dangers (for instance it can explode all by itself, unlike propane etc.,
> it has wider flammability limits in air than propane, lower flash point,
> and more) of acetylene.
>
> -- Peter Fairbrother

My late Dad and his brother had an original Oxy/Acetylene welding kit
(pre-WWII) which used an "acetylene generator" and compressed Oxygen.
Problem is that you have to have a low pressure torch (not a modern
"Saphire" style) as Acetylene cannot be compressed without exploding.
I don't know what the limiting factor is but, IIRC, the torch used
circa 2 psi.

He kept the torch and oxygen bottle throughout the war - don't know
what happened to the generator.  When his brother wanted to set-up a
welding kit again, the torch, hoses and Oxy regulator, etc, went to
him.  The Oxy bottle which, as I understand it, was owned by Dad and
Unc was, previously to WWII, swapped for a refilled one at an agent in
Carlisle where they lived at that time (ie, no rental).  It proved to
be NBG as it was "round-bottomed" and current bottles are "flat
bottomed" so BOC wouldn't even take it away.  The regulator wasn't
suitable for current Oxy-bottle pressures either.  To cut a long story
short, my uncle did get the torch working with new regulators and such
like, but it was never easy to use with bottled Acetylene - too touchy
on the regulator.

When my Dad and I wanted to do some serious welding, we invested in a
completely new "BOC Saphire" kit in the '60s.  IIRC, we had to upgrade
(by exchange) the "new" regulators when BOC increased the pressure in
bottles a few years before I finally cancelled the contract - after
Dad passed to the great engineerium above (1992).

houstonceng wrote:
> On Aug 31, 4:34 pm, Peter Fairbrother  wrote:
>> I wrote:
>>> I don't know of any cheap small-scale sources of acetylene, much as I'd
>>> like to - while oxy/MAPP welding is quite possible, it's nowhere near as
>>> easy as oxy/acetylene (though oxy/MAPP is fine for brazing).
>> Come to think of it, you could make acetylene from carbide.
>>
>> 3 kg of carbide, producing 1.1 cu m of acetylene, costs £20.75, about
>> £19 per cubic meter: if a H size cylinder costs £77 to refill, that's
>> about £10 per cubic meter of useable acetylene,
>>
>> So acetylene from carbide costs around twice as much as acetylene in a
>> big cylinder - and no rental, more reasonable delivery fees, no return
>> fees, and available in small quantities.
>>
>> The problem then is the generator to produce the acetylene. Small
>> capacity generators are available at around £40-50, but I do mean small..
>> Apparently you can get bigger generators for welding for third-world
>> use, but I don't know where from.
>>
>> Making your own generator? Could be inexpensive, but I don't advise it
>> unless you know what you are doing, and thoroughly understand the
>> dangers (for instance it can explode all by itself, unlike propane etc.,
>> it has wider flammability limits in air than propane, lower flash point,
>> and more) of acetylene.
>>
>> -- Peter Fairbrother
> 
> My late Dad and his brother had an original Oxy/Acetylene welding kit
> (pre-WWII) which used an "acetylene generator" and compressed Oxygen.
> Problem is that you have to have a low pressure torch (not a modern
> "Saphire" style) as Acetylene cannot be compressed without exploding.
> I don't know what the limiting factor is but, IIRC, the torch used
> circa 2 psi.

Chemically speaking the limit is 15 psig at reasonable room 
temperatures: but you should use a good safety margin, as acetylene is 
seldom pure and the impurities can lower the minimum explosion pressure; 
and the explosive limit is absolute, ie 29 psia (15 psi plus the 14 psi 
of the atmosphere) - however a non-explosive 7 psig torch supply 
*should* be possible.

Unfortunately one of the problems with this idea is that the carbide 
container is sometimes replenished, and when that happens air is 
admitted when it is opened - ouch. The explosive pressure limit for 
acetylene with a little bit of air in it can be much lower - a 2 psi 
maximum may also be used to limit the damage from an explosion, with the 
generator being perhaps built to withstand it.

I don't know what pressure a Sapphire torch uses, but I have a fairly 
ordinary balanced torch which welds okay at 4-5 psi with MAPP gas.


(There are two types of torches, the balanced and injector types. In the 
balanced type the fuel and oxygen supply are at about the same pressure 
and the gases simply mix in the nozzle - in the injector type the oxygen 
(usually) is at a fairly high pressure, maybe 40 psi, and the fuel at a 
much lower pressure, maybe 1 psi - the nozzle is built so that the 
oxygen flow sucks the fuel gas out. I don't know what type a Sapphire 
torch is)


-- Peter Fairbrother

"Peter Fairbrother"  wrote


>>
>> My late Dad and his brother had an original Oxy/Acetylene welding kit
>> (pre-WWII) which used an "acetylene generator" and compressed Oxygen.
>> Problem is that you have to have a low pressure torch (not a modern
>> "Saphire" style) as Acetylene cannot be compressed without exploding.
>> I don't know what the limiting factor is but, IIRC, the torch used
>> circa 2 psi.
>
> Chemically speaking the limit is 15 psig at reasonable room temperatures: 
> but you should use a good safety margin, as acetylene is seldom pure and 
> the impurities can lower the minimum explosion pressure; and the explosive 
> limit is absolute, ie 29 psia (15 psi plus the 14 psi of the atmosphere) - 
> however a non-explosive 7 psig torch supply *should* be possible.
>
> Unfortunately one of the problems with this idea is that the carbide 
> container is sometimes replenished, and when that happens air is admitted 
> when it is opened - ouch. The explosive pressure limit for acetylene with 
> a little bit of air in it can be much lower - a 2 psi maximum may also be 
> used to limit the damage from an explosion, with the generator being 
> perhaps built to withstand it.
>
> I don't know what pressure a Sapphire torch uses, but I have a fairly 
> ordinary balanced torch which welds okay at 4-5 psi with MAPP gas.
>


FYI I have a Butbro lightweight torch which can take up to no: 25 nozzles 
which will weld up to about 1/4" steel.

I've just check my acetylene regulator and the output pressure gauges has 
the green sector as being up to 0.6 bar and the red sector starts at 1.5 
bar. I believe acteylene self detonates at about 2 bar. When doing heavy 
work with the no:25 nozzle I find that I need to have the pressure at the 
top end of the green.

And before someone asks, the BOC size J acetylene cylinders are filled to 
15.5 bar at 15 degrees C but its disolved in acetone and also I think the 
cylinder is packed with asbestos or some other material.

All flamable gases have both a high and lower explosion limit when mixed 
with air. Acetylene and Hydrogen are considered the worst, and acetylene in 
particular has a very wide band between the LEL and HEL. LELs and HELs are 
normally expressed as the percentage of flammable gas in air which will 
ignite.

"John"  wrote

>
> All flamable gases have both a high and lower explosion limit when mixed 
> with air. Acetylene and Hydrogen are considered the worst, and acetylene 
> in particular has a very wide band between the LEL and HEL. LELs and HELs 
> are normally expressed as the percentage of flammable gas in air which 
> will ignite.
>
>

Just checked the Safety Datasheet for acetylene. The Flammability range is 
2.4-88 vol% in air.

By comparison Propane's Flammability Limits are 2% to 11% in air.

John wrote:
> "Peter Fairbrother"  wrote
> 
> 
>>> My late Dad and his brother had an original Oxy/Acetylene welding kit
>>> (pre-WWII) which used an "acetylene generator" and compressed Oxygen.
>>> Problem is that you have to have a low pressure torch (not a modern
>>> "Saphire" style) as Acetylene cannot be compressed without exploding.
>>> I don't know what the limiting factor is but, IIRC, the torch used
>>> circa 2 psi.
>> Chemically speaking the limit is 15 psig at reasonable room temperatures: 
>> but you should use a good safety margin, as acetylene is seldom pure and 
>> the impurities can lower the minimum explosion pressure; and the explosive 
>> limit is absolute, ie 29 psia (15 psi plus the 14 psi of the atmosphere) - 
>> however a non-explosive 7 psig torch supply *should* be possible.
>>
>> Unfortunately one of the problems with this idea is that the carbide 
>> container is sometimes replenished, and when that happens air is admitted 
>> when it is opened - ouch. The explosive pressure limit for acetylene with 
>> a little bit of air in it can be much lower - a 2 psi maximum may also be 
>> used to limit the damage from an explosion, with the generator being 
>> perhaps built to withstand it.
>>
>> I don't know what pressure a Sapphire torch uses, but I have a fairly 
>> ordinary balanced torch which welds okay at 4-5 psi with MAPP gas.
>>
> 
> 
> FYI I have a Butbro lightweight torch which can take up to no: 25 nozzles 
> which will weld up to about 1/4" steel.
> 
> I've just check my acetylene regulator and the output pressure gauges has 
> the green sector as being up to 0.6 bar and the red sector starts at 1.5 
> bar. I believe acteylene self detonates at about 2 bar. 

It depends on many factors, including the volume and shape of the 
container (and the impurity levels). Butbro, and many others, may assume 
you only use their equipment and shapes.

The figure I gave of 15 psi is generally regarded as the figure below 
which it has never been known to explode.


When doing heavy
> work with the no:25 nozzle I find that I need to have the pressure at the 
> top end of the green.

That's about 8 psig, still okay.

> 
> And before someone asks, the BOC size J acetylene cylinders are filled to 
> 15.5 bar at 15 degrees C but its disolved in acetone and also I think the 
> cylinder is packed with asbestos or some other material.

Yes - and the gas is dissolved in acetone soaked into the  porous 
contents of the cylinders, rather than being compressed gas.

btw, the porous medium used is "diatomaceous earth" - which 
nitroglycerine is also soaked in to make the safer dynamite.

> 
> All flamable gases have both a high and lower explosion limit when mixed 
> with air. Acetylene and Hydrogen are considered 

among :)

the worst, and acetylene in
> particular has a very wide band between the LEL and HEL. LELs and HELs are 
> normally expressed as the percentage of flammable gas in air which will 
> ignite.

Acetylene has a large explosive air mixture range, as you say later it's 
up to 88% acetylene in air, or 12% air - but that's at 0 psig /14psia 
(atmospheric pressure): increase the absolute pressure a bit and the 
limits change, from 12% air at atmospheric pressure to 0% air at 15 psi.


-- Peter Fairbrother

On or around Sun, 31 Aug 2008 14:25:46 -0000, "John" <John@invalid.invalid>
enlightened us thusly:

>
>"Austin Shackles"  wrote
>
>>>
>>>Does anyone know if there's a cheaper way of setting up an Oxy/
>>>Acetylene welding/brazing kit, than hiring bottles from BOC.
>>>
>>
>> I rent 'em from Air Products.  not exactly cheap, still, but a lot less 
>> than
>> BOC
>
>
>Do you have any prices for Air Products? 
>

hmmm.  tricky.  It's all done by direct debit thing, I'd need to find a bit
of paper.

Mind, they recently screwed around with the distribution network.  Luckily,
the place not too far away continues to get them as a customer and swaps
them out with their customers, even though they're not a full-blown agent
any more.
-- 
Austin Shackles.  www.ddol-las.net  my opinions are just that
Travel The Galaxy!  Meet Fascinating Life Forms...
------------------------------------------------\   
   >>  http://www.schlockmercenary.com/  <<      \  ...and Kill them.
a webcartoon by Howard Tayler; I like it, maybe you will too!

Peter Fairbrother wrote:

> The figure I gave of 15 psi is generally regarded as the figure below 
> which it has never been known to explode.

Thermodynamic calculations for pure acetylene put it at 274 kPa, or 23.2 
psi (= 39.7 psia) for infinite volumes @ 25 C. A Butbro gauge which goes 
red at 22 psi is likely taking advantage of small volume factors and 
perhaps statistics as well.

I'd still stick by 15 psi for everyday use, with a safety margin.


<digress>

I do this chemistry stuff in my sleep - not only can I do it, I actually 
do do it. I once got 99% in an exam (my chemistry O level), and 
furiously demanded my teacher ask the examiners to explain my mistake. 
They replied that they had taken off a mark for bad handwriting.

Which was - I don't know exactly what - as I had just recently blown off 
several fingers.



When it comes to being infallible, or very nearly always right, as is 
required of eg some university professors, things can get weird. For 
simple chemistry, for me, it was usually just a question of sanity 
checking my replies. No great problem.

But then I became a cryptologist instead of a chemist, and being right 
became different. The simple math aspect of cryptology is nice, because 
either the math is right or it isn't, forevermore - but the math aspect 
isn't everything, and there are scumbags^H^H^H^H^H fellow researchers 
who want to find fault in what you do. And who can sometimes even come 
up with better math. And of course I try and do it to them^H^H^H^H find 
fault with their work too, and am inordinately pleased when I succeed.

And surprisingly often work is just simply wrong, not just insecure, due 
to bad math, bad procedures, or bad peer review.

Sometimes you prove someone else's work insecure, and watch them gnaw 
their livers - sometimes someone else proves your work is insecure, and 
you gnaw your own liver. Which hurts, especially if you have put 
yourself on the line.

This is as it should be, as security is about what is actually possible, 
not what you, or theory, think is possible.

Nowadays for crypto work, apart from my published papers, I don't try to 
be infallible any more in casual talk like usenet.



But for giving practical/engineering chemistry-related advice about a 
possibly dangerous situation, I do take care - not that I accept any 
legal responsibility, I don't.

But how would I feel if someone followed my advice and lost a few 
fingers (been there, done that), or killed himself, or God forbid, 
killed some else? Not good. So I try to be accurate, and give safe advice.

</digress>


-- Peter (beery) Fairbrother

On Sun, 31 Aug 2008 22:09:56 +0100, Peter Fairbrother 
wrote:

>Peter Fairbrother wrote:
>
>> The figure I gave of 15 psi is generally regarded as the figure below 
>> which it has never been known to explode.
>
>Thermodynamic calculations for pure acetylene put it at 274 kPa, or 23.2 
>psi (= 39.7 psia) for infinite volumes @ 25 C. A Butbro gauge which goes 
>red at 22 psi is likely taking advantage of small volume factors and 
>perhaps statistics as well.
>
>I'd still stick by 15 psi for everyday use, with a safety margin.
>
>
><digress>
>
>I do this chemistry stuff in my sleep - not only can I do it, I actually 
>do do it. I once got 99% in an exam (my chemistry O level), and 
>furiously demanded my teacher ask the examiners to explain my mistake. 
>They replied that they had taken off a mark for bad handwriting.
>
>Which was - I don't know exactly what - as I had just recently blown off 
>several fingers.
>


For me, it was the monthly chemistry tests at school. On one of them I got
marked down 4% (one mark). On protest, It appeared that The teacher's
preferred answer to "what is the product of combustion of hydrogen in oxygen?"
was "pure water" instead of the grammatically correct "water" that I had
tendered. I assume that the staff felt the need to knock down the smart alecs
once in a while.

I think it was just the case that O levels were too easy for anyone with an
interest in the way things work. Don't get me started on the modern abortion
of a compromise between CSE and O level. The youngest has just done his :-|


Mark Rand
RTFM

"Austin Shackles"  wrote in 
message news:qo0mb4l0vqnltgbp93jjlepetr8vl1bh2g@4ax.com...
> On or around Sun, 31 Aug 2008 14:25:46 -0000, "John" 
> <John@invalid.invalid>
> enlightened us thusly:
>
>>
>>"Austin Shackles"  wrote
>>
>>>>
>>>>Does anyone know if there's a cheaper way of setting up an Oxy/
>>>>Acetylene welding/brazing kit, than hiring bottles from BOC.
>>>>

I'd also be very interested to know of a cheaper supplier of full sized 
Oxy/Acetylene bottles than BOC and without resorting to any complicated 
Direct Debit arrangement etc
Are there such suppliers?
Brad

On or around Mon, 1 Sep 2008 13:54:15 +0100, "BRAD"
 enlightened us thusly:

>
>"Austin Shackles"  wrote in 
>message news:qo0mb4l0vqnltgbp93jjlepetr8vl1bh2g@4ax.com...
>> On or around Sun, 31 Aug 2008 14:25:46 -0000, "John" 
>> <John@invalid.invalid>
>> enlightened us thusly:
>>
>>>
>>>"Austin Shackles"  wrote
>>>
>>>>>
>>>>>Does anyone know if there's a cheaper way of setting up an Oxy/
>>>>>Acetylene welding/brazing kit, than hiring bottles from BOC.
>>>>>
>
>I'd also be very interested to know of a cheaper supplier of full sized 
>Oxy/Acetylene bottles than BOC and without resorting to any complicated 
>Direct Debit arrangement etc
>Are there such suppliers?
>Brad 
>

dunno.  Best bet would be find yer nearest large steel molishing type place
and see if you can do a deal.

Air Products have fewer hoops to jump through, but still want bottle rental
by DD, I think.

I suppose technically you could buy a set of bottles, and then exchange
them.
-- 
Austin Shackles.  www.ddol-las.net  my opinions are just that
Travel The Galaxy!  Meet Fascinating Life Forms...
------------------------------------------------\   
   >>  http://www.schlockmercenary.com/  <<      \  ...and Kill them.
a webcartoon by Howard Tayler; I like it, maybe you will too!

Not wishing to teach my grandmother to suck eggs here, but I can vouch
for what others have said about the dangers of pressurising acetylyne
even a relatively little bit. A regular Guy Fawkes night trick was to
fill a condom with oxy-acetylne mix which then makes a great bang when
the bonfire's lit. Then on about the 3rd occasion my mate did this,
the gas detonated whilst he was filling it - what initially appeared
to a Laurel and Hardy moment was actually rather more serious and he'd
perforated both ear drums. Although his hearing did return somewhat,
some damage was permanent and, for instance, he could no longer go
scuba diving. This is only at balloon pressure remember. There was a
view that the condom lubricant was a contributory factor, so
presumably risk can be reduced by keeping a carbide generator very
clean and oil free. I've also heard of the gas evolving from "spent"
carbide exploding when being carried in a sealed container - an ammo
can used for carrying stuff in caves. It went off when banged on a
rock, slightly injuring the hand of the bloke carrying it. He said
he'd have been hurt rather worse if the rock hadn't been shielding him
from it when it went off. (carbide lights used to be used for caving)

Hywel

hyweldavies wrote:
> Not wishing to teach my grandmother to suck eggs here, but I can vouch
> for what others have said about the dangers of pressurising acetylyne
> even a relatively little bit. A regular Guy Fawkes night trick was to
> fill a condom with oxy-acetylne mix which then makes a great bang when
> the bonfire's lit. 

Oxy-acetylene mix is even more dangerous than acetylene - by far!

The ignition energy required is less than 1/10, maybe 1/100th of the 
ignition energy of aceteylene itself - which is still low.

Acetylene/oxygen mixes can detonate at 1/10th atmospheric pressure, or less.



Pure acetylene by itself is not just dangerous by detonation, which 
requires maybe 18 psia - it also deflagrates (burns slowly - but slowly 
can be anything from very slow to bl**dy fast indeed!) at lower 
pressures than pure acetylene, including less than atmospheric pressure.


Then on about the 3rd occasion my mate did this,
> the gas detonated whilst he was filling it - what initially appeared
> to a Laurel and Hardy moment was actually rather more serious and he'd
> perforated both ear drums. Although his hearing did return somewhat,
> some damage was permanent and, for instance, he could no longer go
> scuba diving. 

:(

I have holes in both my eardrums - I can (or could - they seem to be 
blocked now) blow bubbles from them in the bath. Maybe they've regrown, 
or filed with wax, but loud bangs do that.

This is only at balloon pressure remember. There was a
> view that the condom lubricant was a contributory factor, so
> presumably risk can be reduced by keeping a carbide generator very
> clean and oil free. 

No.

Cleanliness and oil-freeness are requirements - but as I said above, the 
ignition energy of acetylene/oxygen mixes is very low indeed.

The acetylene/oxygen ignition energy is far less than the ignition 
energy of the condom lubricant in oxygen, probably ooms less - but then 
perhaps even a bursting balloon might give enough energy to ignite an 
oxygen/acetylene mix.

Not kidding.

I've also heard of the gas evolving from "spent"
> carbide exploding when being carried in a sealed container - an ammo
> can used for carrying stuff in caves. It went off when banged on a
> rock, slightly injuring the hand of the bloke carrying it. He said
> he'd have been hurt rather worse if the rock hadn't been shielding him
> from it when it went off. 

Not surprising. Spent carbide is dangerous, and will give off acetylene 
for a good while.

> (carbide lights used to be used for caving)

Still are, occasionally.

> Hywel

I did sanity-check this, but I'm so drunk right now that I'm not sure of 
my own sanity -

- and I'm not infallible anyway, as my lack of fingers will attest.


-- Peter Fairbrother

Peter Fairbrother wrote:
> hyweldavies wrote:
>> Not wishing to teach my grandmother to suck eggs here, but I can vouch
>> for what others have said about the dangers of pressurising acetylyne
>> even a relatively little bit. A regular Guy Fawkes night trick was to
>> fill a condom with oxy-acetylne mix which then makes a great bang when
>> the bonfire's lit. 
> 
> Oxy-acetylene mix is even more dangerous than acetylene - by far!
> 
> The ignition energy required is less than 1/10, maybe 1/100th of the 
> ignition energy of aceteylene itself - which is still low.
> 
> Acetylene/oxygen mixes can detonate at 1/10th atmospheric pressure, or 
> less.
> 
> 
> 
> 

Im-Pure acetylene by itself is not just dangerous by detonation, which
> requires maybe 18 psia - it also deflagrates (burns slowly - but slowly 
> can be anything from very slow to bl**dy fast indeed!) at lower 
> pressures than 

im-pure acetylene

^^ detonates

, including less than atmospheric pressure.

bleeaarggh

-- Peter Fairbrother
> 
> 
> Then on about the 3rd occasion my mate did this,
>> the gas detonated whilst he was filling it - what initially appeared
>> to a Laurel and Hardy moment was actually rather more serious and he'd
>> perforated both ear drums. Although his hearing did return somewhat,
>> some damage was permanent and, for instance, he could no longer go
>> scuba diving. 
> 
> :(
> 
> I have holes in both my eardrums - I can (or could - they seem to be 
> blocked now) blow bubbles from them in the bath. Maybe they've regrown, 
> or filed with wax, but loud bangs do that.
> 
> This is only at balloon pressure remember. There was a
>> view that the condom lubricant was a contributory factor, so
>> presumably risk can be reduced by keeping a carbide generator very
>> clean and oil free. 
> 
> No.
> 
> Cleanliness and oil-freeness are requirements - but as I said above, the 
> ignition energy of acetylene/oxygen mixes is very low indeed.
> 
> The acetylene/oxygen ignition energy is far less than the ignition 
> energy of the condom lubricant in oxygen, probably ooms less - but then 
> perhaps even a bursting balloon might give enough energy to ignite an 
> oxygen/acetylene mix.
> 
> Not kidding.
> 
> I've also heard of the gas evolving from "spent"
>> carbide exploding when being carried in a sealed container - an ammo
>> can used for carrying stuff in caves. It went off when banged on a
>> rock, slightly injuring the hand of the bloke carrying it. He said
>> he'd have been hurt rather worse if the rock hadn't been shielding him
>> from it when it went off. 
> 
> Not surprising. Spent carbide is dangerous, and will give off acetylene 
> for a good while.
> 
>> (carbide lights used to be used for caving)
> 
> Still are, occasionally.
> 
>> Hywel
> 
> I did sanity-check this, but I'm so drunk right now that I'm not sure of 
> my own sanity -
> 
> - and I'm not infallible anyway, as my lack of fingers will attest.
> 
> 
> -- Peter Fairbrother

"Peter Fairbrother"  wrote in message 
news:48bf1d73$0$2500$da0feed9@news.zen.co.uk...
>
> I did sanity-check this, but I'm so drunk right now that I'm not sure of 
> my own sanity -

> -- Peter Fairbrother

If there is one thing I have learned since the advent of the Internet, it is 
never to reply in public when drunk. I always regret it.

Cliff Coggin.

Cliff Coggin wrote:
> "Peter Fairbrother"  wrote in message 
> news:48bf1d73$0$2500$da0feed9@news.zen.co.uk...
>> I did sanity-check this, but I'm so drunk right now that I'm not sure of 
>> my own sanity -
> 
>> -- Peter Fairbrother
> 
> If there is one thing I have learned since the advent of the Internet, it is 
> never to reply in public when drunk. I always regret it.

Y'rright of course. Let me rephrase my reply, hoping this is clearer:


hyweldavies wrote:
 > Not wishing to teach my grandmother to suck eggs here, but I can vouch
 > for what others have said about the dangers of pressurising acetylene
 > even a relatively little bit. A regular Guy Fawkes night trick was to
 > fill a condom with oxy-acetylene mix which then makes a great bang when
 > the bonfire's lit.

Oxy-acetylene mix is even more dangerous than acetylene - by far!

The ignition energy required is less than 1/10, maybe 1/100th of the 
ignition energy of acetylene itself - which is still low.

Acetylene/oxygen mixes can detonate at 1/10th atmospheric pressure, or 
less. Acetylene/air mixes can explode below atmospheric pressure too, 
which is why it's important to flush acetylene hoses immediately before use.



Acetylene without oxygen can not only detonate, which only takes place 
at 15 psia or more, but it can also deflagrate at any pressure.

(A deflagration is when the reaction front moves slower [1] than the 
speed of sound in the material - if it moves above the speed of sound 
it's a detonation, that's the difference between a detonation and a 
deflagration. When a reaction front moves faster than the speed of sound 
some of the energy goes into making shock waves, which can be very damaging.

[1] for acetylene slower can be anything from very slow to very fast 
indeed!)

Most flashbacks in acetylene hoses are deflagrations, not detonations. 
Sometimes acetylene burns inside the torch without oxygen, and that's a 
deflagration too - but the occasional "pop" may be a detonation of 
oxygen/acetylene mix.

Another example of a deflagration is in the regulator of an acetylene 
cylinder - this *always* happens to some extent when acetylene is used. 
Acetylene regulator passages are made small to limit the volume and thus 
lower the rate of reaction so that only a small proportion of the 
acetylene decomposes, and to ensure the deflagration does not become a 
detonation.

So don't use anything except a proper regulator designed for acetylene 
with acetylene!


Then on about the 3rd occasion my mate did this,
 > the gas detonated whilst he was filling it - what initially appeared
 > to a Laurel and Hardy moment was actually rather more serious and he'd
 > perforated both ear drums. Although his hearing did return somewhat,
 > some damage was permanent and, for instance, he could no longer go
 > scuba diving.

:(

I have holes in both my eardrums - I can (or could - they seem to be 
blocked now) blow bubbles from them in the bath. Maybe they've regrown, 
or filled with wax, but loud bangs do that.

This is only at balloon pressure remember. There was a
 > view that the condom lubricant was a contributory factor, so
 > presumably risk can be reduced by keeping a carbide generator very
 > clean and oil free.

Not my view. As I said above, the ignition energy of acetylene/oxygen 
mixes is very low indeed, far less than the ignition energy of the 
condom lubricant in oxygen, probably OOMs [2] less - but then perhaps 
even a bursting balloon might give enough energy to ignite an 
oxygen/acetylene mix.

Not kidding.

[2] orders of magnitude

I've also heard of the gas evolving from "spent"
 > carbide exploding when being carried in a sealed container - an ammo
 > can used for carrying stuff in caves. It went off when banged on a
 > rock, slightly injuring the hand of the bloke carrying it. He said
 > he'd have been hurt rather worse if the rock hadn't been shielding him
 > from it when it went off.

Not surprising. Spent carbide is dangerous, and will give off acetylene 
for a good while. A polythene bag should be okay, but not a metal 
container in which the gas pressure can rise.

 > (carbide lights used to be used for caving)

Still are, occasionally.

 > Hywel


-- Peter Fairbrother

In article <48bfeb38$0$26091$db0fefd9@news.zen.co.uk>,  
 Peter Fairbrother   in
uk.rec.models.engineering wrote:

>Cliff Coggin wrote:
>> "Peter Fairbrother"  wrote in message 
>> news:48bf1d73$0$2500$da0feed9@news.zen.co.uk...
>>> I did sanity-check this, but I'm so drunk right now that I'm not sure of 
>>> my own sanity -
>> 
>>> -- Peter Fairbrother
>> 
>> If there is one thing I have learned since the advent of the Internet, it is 
>> never to reply in public when drunk. I always regret it.
>
>Y'rright of course. Let me rephrase my reply, hoping this is clearer:
>
>
>hyweldavies wrote:
> > Not wishing to teach my grandmother to suck eggs here, but I can vouch
> > for what others have said about the dangers of pressurising acetylene
> > even a relatively little bit. A regular Guy Fawkes night trick was to
> > fill a condom with oxy-acetylene mix which then makes a great bang when
> > the bonfire's lit.
>

Also used at party time, balloon with OA inside, nitrogen tri-iodide
outside.

The other use of welding kit on Guy Fawkes night is handing out old,
damp arc welding rods to the youngsters, telling them that they are
sparklers and watching their attempts to obtain ignition from the
bonfire.  Once the kidz have gained a nice cherry-red colour we give
them real sparklers, otherwise it would be unkind.

 <snip>

>
>Not surprising. Spent carbide is dangerous, and will give off acetylene 
>for a good while. A polythene bag should be okay, but not a metal 
>container in which the gas pressure can rise.
>
> > (carbide lights used to be used for caving)
>
>Still are, occasionally.
>

Where do you buy driplamp carbide these days?  Halfords no longer
stock it.  Wouldn't mind a bit to play with, for old times sake.

Regards,

David P.

In article <48bab9ec$0$26075$db0fefd9@news.zen.co.uk>, Peter Fairbrother 
 writes
>
>Making your own generator? Could be inexpensive, but I don't advise it 
>unless you know what you are doing, and thoroughly understand the 
>dangers (for instance it can explode all by itself, unlike propane 
>etc., it has wider flammability limits in air than propane, lower flash 
>point, and more) of acetylene.
>
IIRC from my chemistry days, acetylene under pressure does indeed have a 
material tendency to explode spontaneously (quite possibly encouraged by 
the metal of the cylinder walls). The acetylene cylinders used actually 
contain the acetylene dissolved under pressure in liquid acetone, and 
(again, IIRC) some solid material to stop it all slopping around.

Also worth bearing in mind that the acetylene/oxygen reaction is *much* 
more exothermic and violent than that of propane or butane. I once saw a 
demonstration of a stoichiometric mix of the two in a milk bottle being 
ignited (very carefully with a long rod and heavy screening); all that 
was left afterwards was powdered glass ( and a loud ringing in the 
ears).

Don't try this at home folks....

David
-- 
David Littlewood

David Littlewood wrote:
> In article <48bab9ec$0$26075$db0fefd9@news.zen.co.uk>, Peter Fairbrother 
>  writes
>>
>> Making your own generator? Could be inexpensive, but I don't advise it 
>> unless you know what you are doing, and thoroughly understand the 
>> dangers (for instance it can explode all by itself, unlike propane 
>> etc., it has wider flammability limits in air than propane, lower 
>> flash point, and more) of acetylene.
>>
> IIRC from my chemistry days, acetylene under pressure does indeed have a 
> material tendency to explode spontaneously (quite possibly encouraged by 
> the metal of the cylinder walls). The acetylene cylinders used actually 
> contain the acetylene dissolved under pressure in liquid acetone, and 
> (again, IIRC) some solid material to stop it all slopping around.

In the UK it's usually porous diatomaceous earth and cement, sometimes 
with carbon added, which completely fills the cylinder. The acetone 
comes about half-way up.

The porous stuff is there primarily to prevent detonations; but it also 
filters the acetone from the fizz caused by decrease in pressure when 
the valve is opened (that's why an acetylene cylinder should be kept and 
used in an upright position).

The porous stuff will also slow a deflagration (a non-detonating flame 
front) - but it won't stop one. If a cylinder starts vibrating or 
rocking and gets hot, get out of there fast!

> Also worth bearing in mind that the acetylene/oxygen reaction is *much* 
> more exothermic and violent than that of propane or butane. I once saw a 
> demonstration of a stoichiometric mix of the two in a milk bottle being 
> ignited (very carefully with a long rod and heavy screening); all that 
> was left afterwards was powdered glass ( and a loud ringing in the ears).
> 
> Don't try this at home folks....

That sounds like a detonation - which can be much more violent than a 
fast deflagration (flame). Acetylene/oxygen mixes tend to detonate much 
more easily than eg propane/oxygen mixes.

For an acetylene/oxygen mix initially at atmospheric pressure the 
maximum shock pressure can reach 6,000 psi for a detonation (as opposed 
to about 90 psia for a deflagration).


I won't repeat it all here, but I just posted a whole lot of information 
about acetylene (probably much more than you want to know) on the 
sci.engr.joining.welding newsgroup, under the thread titles "Splitter on 
Acetylene tank" and "Another acetylene question."

-- Peter Fairbrother

Here in South Africa we have Afrox which is a subsidiary of BOC  - it
is also regarded as very expensive.

I use oxy/propane and I purchased my most recent oxy refill from a gas
outlet (which gets the refilled cylinders from Afrox) and paid less
than I would have from Afrox - and I got to chose my own cylinder!


This is a recent press release from Afrox:
"The factory currently exports more than 50% of its total production.
The BOC group, Afrox's parent company, was recently acquired by the
Linde group. This is likely to open up many new export markets for the
factory's products."

Tim