Nylon tubing for flammable gas distribution?
William D Danielson_Jr.
Is nylon flexible tubing acceptable for distributing low pressure
flammable gases in a chemistry lab?
I will must carry oxygen and methane at 5-15 psi in separate lines from
a gas bottle, through a regulator, through 50 ft of tubing, drop to 4
separate fume hoods, connect to a special nozzle where the gases mix and
are burned in a coating application process.
This is currently done in a rats nest of 1/4 nylon flex tubing with
pushlock plastic fittings. I am a mechanical engineer task to clean up
this mess. I am used to doing compressed air piping in manufacturing
plants but am not familiar with good practices for low pressure
flammable gas plumbing in a lab setting. My predecessors used nylon
tubes and pushlock plastic fittings just because it was the cheapest way
to go.
Is nylon OK, or should I use another approach like copper, steel or
aluminum tubing or threaded pipe?
Thanks for any advice,
Doug Danielson
Phil Thompson
"William D Danielson_Jr." <wdd...@ibm.net> wrote:
>Is nylon flexible tubing acceptable for distributing low pressure
>flammable gases in a chemistry lab?
Plastic piping (of some sort) is widely used in the UK for
distribution of natural gas. If the area is free of hot surfaces or
impact risk there should be no problem.
Phil
--
---------------------------------------------------------------------------
Process Engineering for the Sugar Industry.
P D Thompson Email : ph...@pdt.u-net.com
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Walter Driedger
Talk to your Swageloc or Parker rep.
But their solutions may be a bit pricey.
William D Danielson_Jr. wrote:
>
> Is nylon flexible tubing acceptable for distributing low pressure
> flammable gases in a chemistry lab?
>
Patrice Nadeau
>>Is nylon flexible tubing acceptable for distributing low pressure
>>flammable gases in a chemistry lab?
>
>distribution of natural gas. If the area is free of hot surfaces or
>impact risk there should be no problem.
>
density polyethylene, I think. Polyethylene is also very cheap.
Something you can trust.
Patrice Nadeau
pna...@po-box.mcgill.ca
Bruce Hamilton
Walter Driedger <drie...@cadvision.com> wrote:
>Talk to your Swageloc or Parker rep.
>But their solutions may be a bit pricey.
They should not be used for permanent reticulation systems
unless your organisation has lots of money to throw away.
Their fittings are intended to be reusable ( and are - if
tightened correctly ), and thus the higher capital cost is
not usually justified in permanent installations.
>William D Danielson_Jr. wrote:
>> Is nylon flexible tubing acceptable for distributing low pressure
>> flammable gases in a chemistry lab?
You need to talk with your local building inspectors and
dangerous goods authorities. They should mandate what are
acceptable practices for flammable and oxidant gases in
building and DG codes.
>> I will must carry oxygen and methane at 5-15 psi in separate lines from
>> a gas bottle, through a regulator, through 50 ft of tubing, drop to 4
>> separate fume hoods, connect to a special nozzle where the gases mix and
>> are burned in a coating application process.
Frankly, I think you may have several problems.
Here in NZ, our laboratories normally use copper tubing to carry
gases to point-of-use fittings in laboratory buildings ( except,
of course, acetylene - which is in steel pipe ). These pipes
are usually installed and tested by our local plumber/gasfitter
and are fairly cheap. The cost goes up slightly if the system
is solvent-washed for instrument-grade gases. As you are planning
on piping oxygen, you will have to remove all traces of drawing
oil hydrocarbons from the system, and if using tapered thread
fittings, use an " oxygen service " grade of PTFE tape.
The reason for metal is because the buildings are constructed of
flammable materials that can burn and melt polymeric pipes
thus releasing more oxidant and fuel gases to the fire. Polymeric
pipes are only normally used for transporting gases through
underground pipes to buildings, or in large installations that
also have pressure drop or other safety sensors.
>> This is currently done in a rats nest of 1/4 nylon flex tubing with
>> pushlock plastic fittings. I am a mechanical engineer task to clean up
>> this mess.....
>> Is nylon OK, or should I use another approach like copper, steel or
>> aluminum tubing or threaded pipe?
You need to talk to the local building code experts. Here we
use brazed copper pipe, with the only thread fittings being
the non-return valves and final bench fitting. The fact that
the gases are going to be mixed should also be taken into
consideration. In general, if using a natural gas - ambient
air burner, no extra precautions are necessary, *however*
if you are mixing two pressurised gases in a burner, then safety
devices - such as flashback arrestors - may be required.
Once again it depends on the attitude of your local authority,
or your insurance company. Once upon a time laboratories
coyuld claim to be "test areas" and obtain exemptions from
certain regulations, these days such exemptions are usually
not permitted.
We have flashback arrestors on all fuel gas lines just
downstream from the regulators. I'd go with metal pipes
in a laboratory for all flammable and oxidant gases,
regardless of what the regulators state - the cost of
using 3/8" copper pipe feeding 1/4" risers is fairly low,
and it's not that difficult to solvent clean and flsuh
copper pipe systems for oxygen service.
If you don't want to braze the fittings, there are a range
of "one-time use " fittings that can be used, and yet are
much cheaper than Parker and Swagelok. Talk to any
plumber/gasfitter for the best value for money.
Bruce Hamilton
Naomi Pearson
On Wed, 30 Jul 1997 22:28:27 -0600, Walter Driedger
<drie...@cadvision.com> wrote:
>Talk to your Swageloc or Parker rep.
>But their solutions may be a bit pricey.
>
>William D Danielson_Jr. wrote:
>>
>> Is nylon flexible tubing acceptable for distributing low pressure
>> flammable gases in a chemistry lab?
>>
>> I will must carry oxygen and methane at 5-15 psi in separate lines from
>> a gas bottle, through a regulator, through 50 ft of tubing, drop to 4
>> separate fume hoods, connect to a special nozzle where the gases mix and
>> are burned in a coating application process.
>>
>> This is currently done in a rats nest of 1/4 nylon flex tubing with
>> pushlock plastic fittings. I am a mechanical engineer task to clean up
>> this mess. I am used to doing compressed air piping in manufacturing
>> plants but am not familiar with good practices for low pressure
>> flammable gas plumbing in a lab setting. My predecessors used nylon
>> tubes and pushlock plastic fittings just because it was the cheapest way
>> to go.
>>
>> Is nylon OK, or should I use another approach like copper, steel or
>> aluminum tubing or threaded pipe?
>>
>> Thanks for any advice,
>>
>> Doug Danielson
Nylon distribution-pipework is used as the reticulation system for
natural gas (ie methane essentially) in the city of Sydney in NSW,
Australia, so that is clearly OK for at least low pressures. However,
carrying oxy on a continuous basis in an organic (ie potentially
combustible) conduit such as nylon, rather than say copper or
aluminium may be asking for some trouble. Grant Pearson
David Leung
There is nothing wrong with using nylon tubing and pushlock fittings, but
they tend to be hard to bend and form into place. But if your set up is
going to be permanent and doesn't require flexibility, and if you have
some time on your hands, you should think about using brass tubing and
fittings. If you are delivering wet gases then you should think about
using stainless tubing and fittings to prevent corrosion and
contamination.
Cheers
David
<><><><><><><><><><><><><><><><><><><><><><><><><><><>
supr...@engsoc.carleton.ca
Mech. Eng'ing @ Carleton University
William R. Penrose
>I will must carry oxygen and methane at 5-15 psi in separate lines from
>a gas bottle, through a regulator, through 50 ft of tubing, drop to 4
>separate fume hoods, connect to a special nozzle where the gases mix and
>are burned in a coating application process.
Because this seems to be a permanent installation in an industrial setting, ,
I would take the time to do it right. Methane, especially, is a problem,
since it can leak and accumulate near the ceiling until it is detonated by a
lighting fixture or some other way.
There may be local codes or industry standards for this type of piping.
Your company's insurance company may also be able to help you find the
right standards. For instance, for piping arsine around in Illinois, you need
a sealed, vented cabinet for the gas bottles. Concentric pipes are neededfor
distribution, with the arsine in the middle pipe, and a vacuum in the annular
space.
If there are no insurance or local standards, I'd be inclined to use copper
pipe and brass fittings with brass needle valves, solidly mounted. If cost
were not an object, I'd use stainless instead. And buy a couple of methane
detectors to mount near the ceiling over the system.
This doesn't really take much longer than stringing new plastic tubing.
Bill
************************************************************
Bill Penrose, President, Custom Sensor Solutions, Inc.
526 West Franklin Avenue, Naperville IL 60540, USA
630-548-3548, fax 630-369-9618, email wpen...@interaccess.com
************************************************************
Purveyors of contract R&D and gas sensor-based product
development to this and nearby galaxies.
************************************************************
Wes Treen
Walter Driedger wrote:
>
> Talk to your Swageloc or Parker rep.
> But their solutions may be a bit pricey.
>
> William D Danielson_Jr. wrote:
> >
> > Is nylon flexible tubing acceptable for distributing low pressure
> > flammable gases in a chemistry lab?
> >
> > a gas bottle, through a regulator, through 50 ft of tubing, drop to 4
> > separate fume hoods, connect to a special nozzle where the gases mix and
> > are burned in a coating application process.
> >
> > pushlock plastic fittings. I am a mechanical engineer task to clean up
> > this mess. I am used to doing compressed air piping in manufacturing
> > plants but am not familiar with good practices for low pressure
> > flammable gas plumbing in a lab setting. My predecessors used nylon
> > tubes and pushlock plastic fittings just because it was the cheapest way
> > to go.
> >
> > Is nylon OK, or should I use another approach like copper, steel or
> > aluminum tubing or threaded pipe?
> >
> > Thanks for any advice,
> >
> > Doug Danielson
Hi Doug
Sorry to be an Ass here, But Heed My Words.....It'll save your life
and prevent law suits. etc. OK....
You Shall not , and will NOT!!! use Nylon or any soft, or hard,
non-permiable/permiable device for the transport of any flammable media
when combined with an oxidizer in the same media/device .PERIOD!!!!
IE "You don't use one Hose to supply an Oxy-acetylene torch its fuel".
And in the same likeness ....."You will NOT try to supply methane and
oxygen down the same line .......EVER..."
If you need to combine the two gases, Combine them at the outlet
to atmosphere. OKay...
Also Make sure you have 'flash back arresters',installed on the oxidant
and fuel lines, a few feet at least,in front of the supply tanks
before you start.
Cheers!! to a long and save exsistance!!
With this,base your hose supply on finances and safety factors. safety
first,eh!!
Regards
WES
Wes Treen
Sorry about that, Doug .....
I was drinking and deriving.....
I miss-read your intentions and thought that your design
would implement the transport of both gases in the same pipe.
Again , Sorry
Andreas, Harry A
In article <5rri7t$m...@bertrand.ccs.carleton.ca>, David Leung
<supr...@engsoc.carleton.ca> wrote:
>There is nothing wrong with using nylon tubing and pushlock fittings, but
>they tend to be hard to bend and form into place. But if your set up is
>going to be permanent and doesn't require flexibility, and if you have
>some time on your hands, you should think about using brass tubing and
>fittings. If you are delivering wet gases then you should think about
>using stainless tubing and fittings to prevent corrosion and
Nylon cold flows. I don't want push lock fittings on a material that cold
flows used with flammable gases around me! Accident waiting to happen.
Harry
A professional is a person who can do his best at a time when he doesn't
particularly feel like it. -Alistair Cooke
William D Danielson_Jr.
William R. Penrose wrote:
>
> In article <33DEB0...@ibm.net> "William D Danielson_Jr." <wdd...@ibm.net> writes:
>
> >a gas bottle, through a regulator, through 50 ft of tubing, drop to 4
> >separate fume hoods, connect to a special nozzle where the gases mix and
> >are burned in a coating application process.
>
> I would take the time to do it right. Methane, especially, is a problem,
> since it can leak and accumulate near the ceiling until it is detonated by a
> lighting fixture or some other way.
>
> There may be local codes or industry standards for this type of piping.
> Your company's insurance company may also be able to help you find the
> right standards. For instance, for piping arsine around in Illinois, you need
> a sealed, vented cabinet for the gas bottles. Concentric pipes are neededfor
> distribution, with the arsine in the middle pipe, and a vacuum in the annular
> space.
>
> If there are no insurance or local standards, I'd be inclined to use copper
> pipe and brass fittings with brass needle valves, solidly mounted. If cost
> were not an object, I'd use stainless instead. And buy a couple of methane
> detectors to mount near the ceiling over the system.
>
> This doesn't really take much longer than stringing new plastic tubing.
>
> Bill
>
> ************************************************************
> Bill Penrose, President, Custom Sensor Solutions, Inc.
> 526 West Franklin Avenue, Naperville IL 60540, USA
> 630-548-3548, fax 630-369-9618, email wpen...@interaccess.com
> ************************************************************
> Purveyors of contract R&D and gas sensor-based product
> development to this and nearby galaxies.
> ************************************************************
Thanks for the reply. Should the copper pipe you refer to be ridgid
copper tubing with hard soldered joints, or are rolls copper tubing and
pushloc or compression fittings acceptable?
Thanks
Doug Danielson
Walter Driedger
William D Danielson_Jr. wrote:
> Thanks for the reply. Should the copper pipe you refer to be ridgid
> copper tubing with hard soldered joints, or are rolls copper tubing and
> pushloc or compression fittings acceptable?
>
> Thanks
>
> Doug Danielson
Compression fittings are not merely good enough, the are the best!
Solder is inferior but cheaper.
Bruce Hamilton
In article <33E938...@cadvision.com>
Walter Driedger <drie...@cadvision.com> writes:
>William D Danielson_Jr. wrote:
>> Thanks for the reply. Should the copper pipe you refer to be ridgid
>> copper tubing with hard soldered joints, or are rolls copper tubing and
>> pushloc or compression fittings acceptable?
>Compression fittings are not merely good enough, the are the best!
>Solder is inferior but cheaper.
He said " hard soldered " so I assume that he meant brazing - using
silver alloys , rather than soft solder using lead alloys. For permanent
gas lines made of copper or bundy tubing, brazing is superior to
compression fittings, and is considerably cheaper. The joints are less
likely to leak over time, and lines can be rapidly fabricated - compression
fittings require undamaged, circular tubing with square end - reasonably
easy with small diameter copper ( 1/8" and 1/4" ) and easy all sizes of
stainless, but not so easy with larger sizes of copper tubing.
The *only* advantages of compression fitting are that they don't require
a flame, and they are reusable, both attributes that are seldom important
when plumbers or gas fitters are installing permanent lines. Talk to the
contractor, finfd out what they routinely do, don't ask them for fancy
systems with expensive fittings if you aren't going to modify it in the
next year or so, and ensure that you specify a minumum pressure drop
over 24 hour hold period to test line integrity - we filled to 200psi, and
required no more than 10psi drop over 24 hours ( allows for some
temperature fluctuations ).
Bruce Hamilton
dewald
>Is nylon flexible tubing acceptable for distributing low pressure
>flammable gases in a chemistry lab?
>
>Is nylon OK, or should I use another approach like copper, steel or
>aluminum tubing or threaded pipe?
>
>Thanks for any advice,
>
>Doug Danielson
This is a typical laboratory setup. the quantities handled are very
small and the dangers minimal. I am surprised they use nylon tubing,
that is very fancy. Usually they use Tygon tubing - much cheaper.
If you want to tidy up and make it look impressive you can replace
the nylon tubing with 3/8" stainless steel tubing and use Swagelock
couplings (hope you know how to connect Swagelock couplings - there is
quite an art to it). Threaded pipe is definitely a no-no in the lab.
Hope this helps you.
dew...@fast.co.za
Walter Driedger
Swageloc fittings are the aforementioned compression fittings. There
are other brands.
Eric Lucas
dewald wrote:
> Threaded pipe is definitely a no-no in the lab.
Why? We have it in various places in our lab, including our natural gas
piping. Tubing and compression fittings like Swage-Lok are simpler, but
there are no other reasons to avoid pipe.
Eric Lucas
Anco S. Blazev
Eric Lucas <ealucas*antispam*@ix.netcom.com> wrote:
I think that the original post was referring to pipes in hi-tech labs,
which conduct high and ultra-high purity gasses. You should not use
threaded fittings for such gasses, due to possible gas trapping,
contamination and uncontrolled leaks.
Best regards,
A. Blazev
Keith Rodgers
> Eric Lucas <ealucas*antispam*@ix.netcom.com> wrote:
>
> : > Threaded pipe is definitely a no-no in the lab.
>
> : Why? We have it in various places in our lab, including our natural gas
> : piping. Tubing and compression fittings like Swage-Lok are simpler, but
> : there are no other reasons to avoid pipe.
The NZ natural gas installation code allows threaded pipe indoors except
where the piping is concealed or underfloor. There joints must be
brazed/welded
--
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