Has anyone used PEX tubing to run compressed air in a shop?

I had copper air lines in my old garage and really liked it. I'm
getting tired of tripping over rubber hoses in the new garage. I think
one of my coworkers that I've loaned tools to before has a PEX crimper,
so if I can borrow a crimper is PEX worth the trouble for an easy 25'
run? Or should I just go copper again now that Cu prices are dropping
again. (of course with PEX, maybe I could buy a 100' roll and run a
line all the way around the garage instead of just down one side...)

Bob

"zxcvbob" wrote in message
...
Has anyone used PEX tubing to run compressed air in a shop?

I had copper air lines in my old garage and really liked it. I'm getting
tired of tripping over rubber hoses in the new garage. I think one of my
coworkers that I've loaned tools to before has a PEX crimper, so if I can
borrow a crimper is PEX worth the trouble for an easy 25' run? Or should
I just go copper again now that Cu prices are dropping again. (of course
with PEX, maybe I could buy a 100' roll and run a line all the way around
the garage instead of just down one side...)

Bob

You need pex-al-pex that can handle air

http://www.flexalpex.com/

http://www.lowesforpros.com/get-to-know-pex
Alternative
There is another kind of PEX piping that is used in residential and
commercial applications and in pressure service on compressed air and
compressed gas systems. It is known as crosslinked
polyethylene-aluminum-crosslinked polyethylene (PEX-AL-PEX).

"Hipupchuck" wrote in message
...
zxcvbob wrote:
Has anyone used PEX tubing to run compressed air in a shop?

I had copper air lines in my old garage and really liked it. I'm getting
tired of tripping over rubber hoses in the new garage. I think one of my
coworkers that I've loaned tools to before has a PEX crimper, so if I can
borrow a crimper is PEX worth the trouble for an easy 25' run? Or should
I just go copper again now that Cu prices are dropping again. (of course
with PEX, maybe I could buy a 100' roll and run a line all the way around
the garage instead of just down one side...)

Bob

Pressure is pressure, water or air. What's it rated at?

Not that simple. While pressure is pressure, water is not nearly as
compressible as air and you don't get the same results with a catastrophic
failure. That is why PVC is not allowed for air use. The shards can cause
serious injury.

Ed Pawlowski wrote:
"zxcvbob" wrote in message
...
Has anyone used PEX tubing to run compressed air in a shop?

I had copper air lines in my old garage and really liked it. I'm getting
tired of tripping over rubber hoses in the new garage. I think one of my
coworkers that I've loaned tools to before has a PEX crimper, so if I can
borrow a crimper is PEX worth the trouble for an easy 25' run? Or should
I just go copper again now that Cu prices are dropping again. (of course
with PEX, maybe I could buy a 100' roll and run a line all the way around
the garage instead of just down one side...)

Bob

You need pex-al-pex that can handle air

http://www.flexalpex.com/

http://www.lowesforpros.com/get-to-know-pex
Alternative
There is another kind of PEX piping that is used in residential and
commercial applications and in pressure service on compressed air and
compressed gas systems. It is known as crosslinked
polyethylene-aluminum-crosslinked polyethylene (PEX-AL-PEX).



Why would I care about oxygen permeability on a compressed air line?
PEX-AL-PEX might be easier to work with tho' because it will take a bend
without trying to spring back. And it should tolerate exposure to UV
better (fluorescent lighting and occasional indirect sunlight.) Will
have to see what the difference in price is...

Thanks,
Bob

In article ,
"Ed Pawlowski" wrote:

PVC is not allowed for air use.

If that's true, there's a few thousand machine shops who are breaking
some sort of rule. It's more or less the standard.

"Smitty Two" wrote in message
news
In article ,
"Ed Pawlowski" wrote:

PVC is not allowed for air use.

If that's true, there's a few thousand machine shops who are breaking
some sort of rule. It's more or less the standard.

Then OSHA has not done an inspection on them.
http://www.osha.gov/dts/hib/hib_data/hib19880520.html

Lots of rules are broken but there is a shortage of inspectors to catch
them. Just as speeding is against the law, many do it,but few are cought.
If there is an accident and someone gets hirt, then look out for lawsuits.

In article ,
"Ralph Mowery" wrote:

"Smitty Two" wrote in message
news
In article ,
"Ed Pawlowski" wrote:

PVC is not allowed for air use.

If that's true, there's a few thousand machine shops who are breaking
some sort of rule. It's more or less the standard.

Then OSHA has not done an inspection on them.
http://www.osha.gov/dts/hib/hib_data/hib19880520.html

Lots of rules are broken but there is a shortage of inspectors to catch
them. Just as speeding is against the law, many do it,but few are cought.
If there is an accident and someone gets hirt, then look out for lawsuits.

Thanks for the link. I read it. I think the danger is highly overstated.
We've had the occasional blowout, but it's always been a failed glue
joint. It's loud and inconvenient, but hardly dangerous. Of course, none
of the thousand or so joints I've personally done have ever failed,
because I'm meticulous with them.

We've had at least a half dozen OSHA inspectors over the last 30 years.
None of them squawked about our PVC air lines. I wonder what's really up
with that. Seems odd to me that PVC could be rated to 200 psi or so and
then explode around 80 or 90. This strikes me as the freak accident
thing. The worst injury cited in your link was a broken nose.

Wonder what they'll outlaw next?

wrote:
On Mon, 15 Jun 2009 09:33:43 -0700, Smitty Two
wrote:

In article ,
"Ed Pawlowski" wrote:

PVC is not allowed for air use.
If that's true, there's a few thousand machine shops who are breaking
some sort of rule. It's more or less the standard.

This is one I would like to see the Mythbusters test.

I understand the theory but I still wonder just how much PVC actually
shatters and how fast/far do the pieces go.
I did try to blow up a 1/2" sch40 PVC pipe (safely around the corner
of a block wall) in a similar manner with CO2 (~800 psi) and it didn't
break. I didn't pursue it farther. The next step was going be a couple
thousand PSI of Argon and that might bring the bomb squad ;-)
I was convinced PVC was pretty tough stuff.

My shop air is in steel pipe tho. If that breaks I know the metal will
be dangerous.


But what happens when the pipe is a few years old, and it's freezing
cold, and somebody bumps it with something metal?

Bob

"zxcvbob" wrote in message
...
wrote:
On Mon, 15 Jun 2009 09:33:43 -0700, Smitty Two
wrote:

In article ,
"Ed Pawlowski" wrote:

PVC is not allowed for air use.
If that's true, there's a few thousand machine shops who are breaking
some sort of rule. It's more or less the standard.

This is one I would like to see the Mythbusters test.

I understand the theory but I still wonder just how much PVC actually
shatters and how fast/far do the pieces go.
I did try to blow up a 1/2" sch40 PVC pipe (safely around the corner
of a block wall) in a similar manner with CO2 (~800 psi) and it didn't
break. I didn't pursue it farther. The next step was going be a couple
thousand PSI of Argon and that might bring the bomb squad ;-)
I was convinced PVC was pretty tough stuff.

My shop air is in steel pipe tho. If that breaks I know the metal will
be dangerous.


But what happens when the pipe is a few years old, and it's freezing cold,
and somebody bumps it with something metal?

Bob

or is exposed to uv light and is brittle?

"Smitty Two" wrote in message
news
In article ,
"Ed Pawlowski" wrote:

PVC is not allowed for air use.

If that's true, there's a few thousand machine shops who are breaking
some sort of rule. It's more or less the standard.


It is an OSHA violation. People have been hurt from it. Manufacturers
warn against it. Driving drunk is wrong too, but stupid people still do it.

"Smitty Two" wrote in message
We've had at least a half dozen OSHA inspectors over the last 30 years.
None of them squawked about our PVC air lines. I wonder what's really up
with that. Seems odd to me that PVC could be rated to 200 psi or so and
then explode around 80 or 90. This strikes me as the freak accident
thing. The worst injury cited in your link was a broken nose.

Wonder what they'll outlaw next?

Smart people don't use it. Stupid people do. Sure, it may never happen,
but I've known of a couple of real cases where it has exploded and people
have been hurt, thought not seriously. Do you really want to take a chance?

PVC can deteriorate over time and exposure to UV. It can become brittle. It
is not made to take a lot of stress that compressible gasses can put on it.

Smitty Two wrote:
....
Thanks for the link. I read it. I think the danger is highly overstated.
We've had the occasional blowout, but it's always been a failed glue
joint. It's loud and inconvenient, but hardly dangerous. Of course, none
of the thousand or so joints I've personally done have ever failed,
because I'm meticulous with them.

We've had at least a half dozen OSHA inspectors over the last 30 years.
None of them squawked about our PVC air lines. I wonder what's really up
with that. Seems odd to me that PVC could be rated to 200 psi or so and
then explode around 80 or 90. This strikes me as the freak accident
thing. The worst injury cited in your link was a broken nose.
....

"PVC piping buried 3 feet underground at a Yakima manufacturing plant
exploded, opening up a crater approximately 4 feet deep by 3 feet
across."

That would have been a doozy in open in a shop likely.

I didn't look for it at this time but I've seen some other OSHA
documents that indicate they're mostly concerned w/ large volume
distribution lines, not the piddly 3/4-1" shop air lines.

IIRC, in that document they also stated most failures were impact, not
simply static failure from overpressure or the like. It indicated
particularly shrapnel is more of a problem in PVC than ductile metal
which makes sense.

In short, I've not used it in shop; if I were to consider it I'd
definitely go Sch 60 or greater instead of just 40 in any place that was
habited routinely. Unless there's a tremendous length of run the
potential relatively small material cost savings seems to not be
sufficient reason to go that way for the average rec'er...

$0.02, imo, ymmv, etc., etc., ...

--

Be careful of that one.

The pex-aluminum laminate is the one that had many failures in the early
days of PEX.

There was much finger-pointing between contractors and manufacurers.
Something about dissimalar materials delaminating...................


"Ed Pawlowski" wrote in message
...

"zxcvbob" wrote in message
...
Has anyone used PEX tubing to run compressed air in a shop?

I had copper air lines in my old garage and really liked it. I'm getting
tired of tripping over rubber hoses in the new garage. I think one of my
coworkers that I've loaned tools to before has a PEX crimper, so if I can
borrow a crimper is PEX worth the trouble for an easy 25' run? Or should
I just go copper again now that Cu prices are dropping again. (of course
with PEX, maybe I could buy a 100' roll and run a line all the way around
the garage instead of just down one side...)

Bob

You need pex-al-pex that can handle air

http://www.flexalpex.com/

http://www.lowesforpros.com/get-to-know-pex
Alternative
There is another kind of PEX piping that is used in residential and
commercial applications and in pressure service on compressed air and
compressed gas systems. It is known as crosslinked
polyethylene-aluminum-crosslinked polyethylene (PEX-AL-PEX).

"Smitty Two" wrote in message
news
In article ,
"Ed Pawlowski" wrote:

PVC is not allowed for air use.

If that's true, there's a few thousand machine shops who are breaking
some sort of rule. It's more or less the standard.

Not so.

Steel pipe, black iron with heavy pattern fittings is "standard".

Metal will fatigue over a very long period of time (or shorter under
repeated stress) and fail with a hairline crack. PVC can bust into shards,
especially in conder weather use.

Ralph Mowery wrote:
"Smitty Two" wrote in message
news
In article ,
"Ralph Mowery" wrote:

"Smitty Two" wrote in message
news
Thanks for the link. I read it. I think the danger is highly overstated.
We've had the occasional blowout, but it's always been a failed glue
joint. It's loud and inconvenient, but hardly dangerous. Of course, none
of the thousand or so joints I've personally done have ever failed,
because I'm meticulous with them.

We've had at least a half dozen OSHA inspectors over the last 30 years.
None of them squawked about our PVC air lines. I wonder what's really up
with that. Seems odd to me that PVC could be rated to 200 psi or so and
then explode around 80 or 90. This strikes me as the freak accident
thing. The worst injury cited in your link was a broken nose.

Wonder what they'll outlaw next?

I work where we have compressed air all over the plant. The compressors
operate on 4160 volts to give an adea of the size. Most of the air is set
around 100 lb. I have seen high dollar filter regulators with plastic bowls
crack and blow out. They are even rated for air. We started replacing them
with metal housings. The regulators only had a 1/2 inch pipe connected to
them,but made a large dent a couple of times on things they hit.



The air pressure on the bowl could be a lot higher
than 100psi because, I believe, the incoming air
hits the bowl first before going into the regulator
body. From your description it sounds as though the
regulators are set to 100psi and the incoming air
pressure could be a lot higher. It wouldn't surprise
me if the supply pressure was over 250psi.

TDD

On Mon, 15 Jun 2009 17:33:09 -0500, against all advice, something
compelled "Ralph Mowery" , to say:

I work where we have compressed air all over the plant. The compressors
operate on 4160 volts to give an adea of the size.


Wow.

Thass a lot a volts.




--

Don't worry about people stealing an idea. If it's original, you will
have to ram it down their throats.
- Howard Aiken

In article , writes:
| On Mon, 15 Jun 2009 09:33:43 -0700, Smitty Two
| wrote:
|
| In article ,
| "Ed Pawlowski" wrote:
|
| PVC is not allowed for air use.
|
| If that's true, there's a few thousand machine shops who are breaking
| some sort of rule. It's more or less the standard.
|
| This is one I would like to see the Mythbusters test.
|
| I understand the theory but I still wonder just how much PVC actually
| shatters and how fast/far do the pieces go.

When they were installing my pressure sewer they screwed up one of the tests
(supposedly it was to be full of water before they applied the air pressure
though I think they must also have gone over pressure) and an exposed
section of PVC pipe exploded in a manhole. I wasn't there to see it, but
I cleaned up the shards which were all over my yard up to ~100ft from the
manhole. I definitely would not want to have been leaning over that manhole
during the test...

Dan Lanciani
ddl@danlan.*com

"Smitty Two" wrote in message
news
In article ,
"Ralph Mowery" wrote:

"Smitty Two" wrote in message
news
Thanks for the link. I read it. I think the danger is highly overstated.
We've had the occasional blowout, but it's always been a failed glue
joint. It's loud and inconvenient, but hardly dangerous. Of course, none
of the thousand or so joints I've personally done have ever failed,
because I'm meticulous with them.

We've had at least a half dozen OSHA inspectors over the last 30 years.
None of them squawked about our PVC air lines. I wonder what's really up
with that. Seems odd to me that PVC could be rated to 200 psi or so and
then explode around 80 or 90. This strikes me as the freak accident
thing. The worst injury cited in your link was a broken nose.

Wonder what they'll outlaw next?

I work where we have compressed air all over the plant. The compressors
operate on 4160 volts to give an adea of the size. Most of the air is set
around 100 lb. I have seen high dollar filter regulators with plastic bowls
crack and blow out. They are even rated for air. We started replacing them
with metal housings. The regulators only had a 1/2 inch pipe connected to
them,but made a large dent a couple of times on things they hit.

"Smitty Two" wrote in message
news
In article ,
"Ed Pawlowski" wrote:

PVC is not allowed for air use.

If that's true, there's a few thousand machine shops who are breaking
some sort of rule. It's more or less the standard.

And that makes it safe?

"Al" wrote in message
...

"Smitty Two" wrote in message
news
In article ,
"Ed Pawlowski" wrote:

PVC is not allowed for air use.

If that's true, there's a few thousand machine shops who are breaking
some sort of rule. It's more or less the standard.

And that makes it safe?

Heres link to read on the subject
http://torque1st.clubfte.com/OSHA_PVC_Pipe.htm

"The Daring Dufas" wrote in message
...
The air pressure on the bowl could be a lot higher
than 100psi because, I believe, the incoming air
hits the bowl first before going into the regulator
body. From your description it sounds as though the
regulators are set to 100psi and the incoming air
pressure could be a lot higher. It wouldn't surprise
me if the supply pressure was over 250psi.

TDD

I may have been misunderstood. The filter regulators that blew out were on
lines that have 100 pounds or less on them. They regulate the air from 100
pounds or less down to usually 45 or 20 pounds. Some of the regulators have
over 300 feet of pipe going to them, maybe 500feet more . That pipe is
from around 3 inches down to 1 inch most of the way. For all practical
purposes we have an unlimiated air supply at 100 psi. Opening a 1 inch line
and letting it just blow is nothing to the supply.

There is also some 250 psi compressors in use but they are not connected so
they can override the 100 psi lines. The capacity of them is about the same
as the 100 psi lines.

"Steve Daniels" wrote in message
...
On Mon, 15 Jun 2009 17:33:09 -0500, against all advice, something
compelled "Ralph Mowery" , to say:

I work where we have compressed air all over the plant. The
compressors
operate on 4160 volts to give an adea of the size.


Wow.

Thass a lot a volts.


Yes it is. The fuses for them are around 3 inches across and 2 feet long.
Where the high voltage is the 13,200 volts that feed transformers and is cut
to the 4160 and 480 volt 3 phase. I am not sure what voltage actually feeds
the plant as we do not deal with that. The 13,200 usually gets cut to 480
volts and is set up on breakers that trip around 400 amps. From there it
goes to panels that break it out to lower amp 480 volt circuits. This is a
very large plant. There are about 40 acers under roof. I am not sure how
they are counting it, but think it is including the number of floors. There
are several buildings and some of them have 7 floors. Most only have 3
floors.

Ralph Mowery wrote:
"The Daring Dufas" wrote in message
...
The air pressure on the bowl could be a lot higher
than 100psi because, I believe, the incoming air
hits the bowl first before going into the regulator
body. From your description it sounds as though the
regulators are set to 100psi and the incoming air
pressure could be a lot higher. It wouldn't surprise
me if the supply pressure was over 250psi.

TDD

I may have been misunderstood. The filter regulators that blew out were on
lines that have 100 pounds or less on them. They regulate the air from 100
pounds or less down to usually 45 or 20 pounds. Some of the regulators have
over 300 feet of pipe going to them, maybe 500feet more . That pipe is
from around 3 inches down to 1 inch most of the way. For all practical
purposes we have an unlimiated air supply at 100 psi. Opening a 1 inch line
and letting it just blow is nothing to the supply.

There is also some 250 psi compressors in use but they are not connected so
they can override the 100 psi lines. The capacity of them is about the same
as the 100 psi lines.



Thanks for the clarification, a lot of the industrial
systems I've seen were very high pressure/volume. A
compressor system like the one at your plant that can
supply 100psi continuously at high volume must be a
sight to behold. Are the compressors reciprocating,
screw or ring?

TDD

On Jun 15, 5:51*am, Hipupchuck wrote:
zxcvbob wrote:
Has anyone used PEX tubing to run compressed air in a shop?

I had copper air lines in my old garage and really liked it. *I'm
getting tired of tripping over rubber hoses in the new garage. *I think
one of my coworkers that I've loaned tools to before has a PEX crimper,
so if I can borrow a crimper is PEX worth the trouble for an easy 25'
run? *Or should I just go copper again now that Cu prices are dropping
again. *(of course with PEX, maybe I could buy a 100' roll and run a
line all the way around the garage instead of just down one side...)

Bob

Pressure is pressure, water or air. What's it rated at?

Pressure is pressure but air is not water.......its a stored energy
thing.

That's why pressure vessels are "hydro-tested" for re-
certification... a pressure vessel that fails when pressurized with
water, fails with a "spurt" not a "boom".

Most, but not all, plastics are not ok for compressed gas
applications ...its a matter of failure mode; ductile vs brittle.


As per Smitty Two's post....a LOT of machine shops / fab shops use PVC
for a quick and easy air systems BUT PVC for air is a major no-no.
Not just a silly rule...as PVC ages it gets brittle and a brittle gas
pressure vessel is a potential fragmentation grenade.

cheers
Bob


cheers
Bob

Ralph Mowery wrote:
"Steve Daniels" wrote in message
...
On Mon, 15 Jun 2009 17:33:09 -0500, against all advice, something
compelled "Ralph Mowery" , to say:

I work where we have compressed air all over the plant. The
compressors
operate on 4160 volts to give an adea of the size.

Wow.

Thass a lot a volts.


Yes it is. The fuses for them are around 3 inches across and 2 feet long.
Where the high voltage is the 13,200 volts that feed transformers and is cut
to the 4160 and 480 volt 3 phase. I am not sure what voltage actually feeds
the plant as we do not deal with that. The 13,200 usually gets cut to 480
volts and is set up on breakers that trip around 400 amps. From there it
goes to panels that break it out to lower amp 480 volt circuits. This is a
very large plant. There are about 40 acers under roof. I am not sure how
they are counting it, but think it is including the number of floors. There
are several buildings and some of them have 7 floors. Most only have 3
floors.



When I worked at the Quajaline Missile Range, the largest
island was only 3 miles long so there was no need for a
higher voltage than 4160. The electrical superintendent
I was working with borrowed a wooden hot stick from the
island electric crew and it's a good thing he was wearing
high voltage gloves because the hot stick turned out to
be slightly damp, his hair stood on end. It was a fine day.

TDD

In article ,
"Ed Pawlowski" wrote:

"Smitty Two" wrote in message
We've had at least a half dozen OSHA inspectors over the last 30 years.
None of them squawked about our PVC air lines. I wonder what's really up
with that. Seems odd to me that PVC could be rated to 200 psi or so and
then explode around 80 or 90. This strikes me as the freak accident
thing. The worst injury cited in your link was a broken nose.

Wonder what they'll outlaw next?

Smart people don't use it. Stupid people do. Sure, it may never happen,
but I've known of a couple of real cases where it has exploded and people
have been hurt, thought not seriously. Do you really want to take a chance?

PVC can deteriorate over time and exposure to UV. It can become brittle. It
is not made to take a lot of stress that compressible gasses can put on it.

Yeah, the world is full of big and little dangers. We all make choices.
I'm perfectly comfortable breaking the ground pin off a plug, sticking a
knife in a toaster, and hiking alone in areas known to have mountain
lions.

But I never tailgate, don't engage in promiscuous sex (for health rather
than moral concerns), don't smoke, and stay away from fast food and junk
food. Those activities are far too dangerous for my personal standards
of safety.

I fly airplanes but think motorcycles are inherently dangerous. I guess
we're each free to use or avoid PVC air lines, depending on our own
interpretation of the potential risks. Are you sure you want to label me
stupid for interpreting those risks differently than you do?

"The Daring Dufas" wrote in message
...
Thanks for the clarification, a lot of the industrial
systems I've seen were very high pressure/volume. A
compressor system like the one at your plant that can
supply 100psi continuously at high volume must be a
sight to behold. Are the compressors reciprocating,
screw or ring?

TDD

I am not sure what the compressors are. I know they are not reciprocating,
but some type of rotary system. I am an electrician and do not deal with
them very much. I usually work in another part of the plant. There are 3
or 4 of each I think. Part of them are for 250 psi and the others are for
100 psi. The 250 air is not usually reduced but used as it. The 100 psi air
is regulated in many applications from 30 to 45 psi but also used as is for
powering numatic valves. I have helped repair some of the instrumentaion on
then and that is about all. From what I remember they are taller than I am
and about 15 feet long. That is motor and compressor sit on a skid. I
don't know much about how the air is distribuited around the plant,but I
have seen several storage (surge) tanks that are about 8 feet tall and 3
feet in diameter. There must be miles of pipe connecting it all together.
There are some big dryers after the compressors. They are dual stages and
full of some kind of chemical/filter. One stage drys the air and the other
stage heats up and gets the moisture out of the chemical. Then they
switch. All automatic. This is not the air compressor a service station
fills yout tires with..However we do use it to fill the tires in the plant
vehicles.

Smitty Two wrote:
In article ,
"Ed Pawlowski" wrote:

"Smitty Two" wrote in message
We've had at least a half dozen OSHA inspectors over the last 30 years.
None of them squawked about our PVC air lines. I wonder what's really up
with that. Seems odd to me that PVC could be rated to 200 psi or so and
then explode around 80 or 90. This strikes me as the freak accident
thing. The worst injury cited in your link was a broken nose.

Wonder what they'll outlaw next?
Smart people don't use it. Stupid people do. Sure, it may never happen,
but I've known of a couple of real cases where it has exploded and people
have been hurt, thought not seriously. Do you really want to take a chance?

PVC can deteriorate over time and exposure to UV. It can become brittle. It
is not made to take a lot of stress that compressible gasses can put on it.

Yeah, the world is full of big and little dangers. We all make choices.
I'm perfectly comfortable breaking the ground pin off a plug, sticking a
knife in a toaster, and hiking alone in areas known to have mountain
lions.

But I never tailgate, don't engage in promiscuous sex (for health rather
than moral concerns), don't smoke, and stay away from fast food and junk
food. Those activities are far too dangerous for my personal standards
of safety.

I fly airplanes but think motorcycles are inherently dangerous. I guess
we're each free to use or avoid PVC air lines, depending on our own
interpretation of the potential risks. Are you sure you want to label me
stupid for interpreting those risks differently than you do?

I wouldn't dare describe you as stupid, deranged perhaps but not stupid.
8~)

TDD

"fftt" wrote in message
...
On Jun 15, 5:51 am, Hipupchuck Pressure is pressure but air is not
water.......its a stored energy
thing.

That's why pressure vessels are "hydro-tested" for re-
certification... a pressure vessel that fails when pressurized with
water, fails with a "spurt" not a "boom".

Most, but not all, plastics are not ok for compressed gas
applications ...its a matter of failure mode; ductile vs brittle.

I did not know for sure, but I was thinking that water would sort of squirt
out if the pipe burst,but air would rush out much faster and give a faster
release of enegery. That would propel the shards much faster.
Where I work we extrude melted plastic under 1500 psi from a hole 3/8 inches
in diameter but it is so thick that is just barley gets out of the pipe.
Water under that same pressure would go across the room. I sort of think
water vers air at 100 psi would act similar.

On Jun 15, 9:16*pm, "Ralph Mowery" wrote:
"fftt" wrote in message

...

On Jun 15, 5:51 am, Hipupchuck Pressure is pressure but air is not
water.......its a stored energy
thing.
That's why pressure vessels are "hydro-tested" *for re-
certification... a pressure vessel that fails when pressurized with
water, fails with a "spurt" not a "boom".
Most, but not all, plastics are not ok for compressed gas
applications ...its a matter of failure mode; ductile vs brittle.

I did not know for sure, but I was thinking that water would sort of squirt
out if the pipe burst,but air would rush out much faster and give a faster
release of enegery. *That would propel the shards much faster.
Where I work we extrude melted plastic under 1500 psi from a hole 3/8 inches
in diameter but it is so thick that is just barley gets out of the pipe.
Water under that same pressure would go across the room. *I sort of think
water vers air at 100 psi would act similar.

Gas under high pressure has WAY more stored energy than water under
the same pressure.

It's a compressibility issue; gases are compressible, water (for
purpose of the this discussion ) is basically incompressible.

cheers
Bob

"Smitty Two" wrote in message
But I never tailgate, don't engage in promiscuous sex (for health rather
than moral concerns), don't smoke, and stay away from fast food and junk
food. Those activities are far too dangerous for my personal standards
of safety.

I fly airplanes but think motorcycles are inherently dangerous. I guess
we're each free to use or avoid PVC air lines, depending on our own
interpretation of the potential risks. Are you sure you want to label me
stupid for interpreting those risks differently than you do?

Yep. Known risk, not recommended by the manufacturer, pretty dumb to use
it. If it was safe, the PVC manufacturers would be touting how simple it is
so they could increase sales, not discourage them.

"Ralph Mowery" wrote in message

I did not know for sure, but I was thinking that water would sort of
squirt out if the pipe burst,but air would rush out much faster and give a
faster release of enegery. That would propel the shards much faster.
Where I work we extrude melted plastic under 1500 psi from a hole 3/8
inches in diameter but it is so thick that is just barley gets out of the
pipe. Water under that same pressure would go across the room. I sort of
think water vers air at 100 psi would act similar.

Water cannot be compressed like air, thus it does not hold the energy that
air can release. When pressure testing at very high pressure, water is the
norm for that reason.

In article ,
Smitty Two wrote:
In article ,
"Ed Pawlowski" wrote:

PVC is not allowed for air use.

If that's true, there's a few thousand machine shops who are breaking
some sort of rule. It's more or less the standard.

This was copied directly from the OSHA web site, it is one of the
first hits from searching google for "PVC compressed air OSHA regulation"

BEGIN QUOTE:

February 28, 1991

MEMORANDUM FOR: R. DAVIS LAYNE
Regional Administrator

FROM: PATRICIA K. CLARK, Director
[Directorate of Enforcement Programs]

SUBJECT: Use of Thermoplastic Pipe in Above Ground Locations



This is in response to your memorandum of January 17, concerning a recently
issued [Safety and Health Information Bulletin (SHIB)] dated December 13,
1990, by the [Directorate of Science, Technology and Medicine]. The SHIB
was issued in connection with the use of thermoplastic pipes in above ground
transportation of compressed air or gases, and was based on the Plastic
Pipe Institute's recommendation, dated December 1, 1989.

You indicated in your memorandum that various companies in your Region
are misinterpreting the SHIB to imply that regular polyvinyl chloride
(PVC) pipes that are designed to meet American Society for Testing and
Materials (ASTM) Standard D1785-86, can be used for transportation of
compressed air and gases. The SHIB, however, means that the pipes must
either be constructed of or be encased in shatter resistant materials.

You requested an official citation issuance policy regarding the use of
PVC pipes for above ground transportation of compressed air or gases.
You also requested our office to describe a citation scenario.

Since PVC material does not possess shatter resistant property, and since
it is very clear from the industry's recognized practice that PVC pipes
are prohibited for above ground transportation of compressed air and
gases (unless the pipelines are encased in shatter resistant material),
any such use by the employers, where employees may be exposed to hazards,
will be in violation of Section 5(a)(1) of the OSH Act. Therefore,
employers who are found to violate the above described conditions or
manufacturer's recommendations, during an OSHA inspection, shall be
issued a 5(a)(1) citation.

For any further clarifications, please have your staff members contact
[the Office of General Industry Enforcement at 202-693-1850].


END QUOTE


It is not difficult to find cases of actual injuries caused by shattered
PVC pipe. Note that there are certain plastic pipe materials specifically
approved for use with compressed air. Some of them may even contain PVC.
But common PVC plumbing pipe is not one of those.

--
There is always an easy solution to every human problem -- neat,
plausible, and wrong." (H L Mencken)

Larry Wasserman - Baltimore Maryland - lwasserm(a)sdf. lonestar. org

In article ,
(Larry W) wrote:


BEGIN QUOTE:


employers who are found to violate the above described conditions or
manufacturer's recommendations, during an OSHA inspection, shall be
issued a 5(a)(1) citation.

What's a 5(a)(1) citation? Slap on the hand with a piece of plastic
pipe? $100,000 fine and the shop doors are padlocked until the pipe is
replaced?



END QUOTE


It is not difficult to find cases of actual injuries caused by shattered
PVC pipe.

It isn't difficult to find cases of actual injuries caused by
screwdrivers.

Note that there are certain plastic pipe materials specifically
approved for use with compressed air. Some of them may even contain PVC.
But common PVC plumbing pipe is not one of those.

Can you tell me what those approved pipes are, and where to find them?

In article ,
"Ed Pawlowski" wrote:

"Smitty Two" wrote in message
But I never tailgate, don't engage in promiscuous sex (for health rather
than moral concerns), don't smoke, and stay away from fast food and junk
food. Those activities are far too dangerous for my personal standards
of safety.

I fly airplanes but think motorcycles are inherently dangerous. I guess
we're each free to use or avoid PVC air lines, depending on our own
interpretation of the potential risks. Are you sure you want to label me
stupid for interpreting those risks differently than you do?

Yep. Known risk, not recommended by the manufacturer, pretty dumb to use
it. If it was safe, the PVC manufacturers would be touting how simple it is
so they could increase sales, not discourage them.

Odd. I hadn't pegged you as the closed-minded, pontificating type before.

"Smitty Two" wrote in message

Yep. Known risk, not recommended by the manufacturer, pretty dumb to use
it. If it was safe, the PVC manufacturers would be touting how simple it
is
so they could increase sales, not discourage them.

Odd. I hadn't pegged you as the closed-minded, pontificating type before.

I don't see not using a potentially hazardous material as being closed
minded. I personally don't care what you do in the privacy of your own
shop, but I do have an opinion about it. I don't view exceeding the
arbitrary speed limit as a big problem as I have control over the vehicle
I'm driving. I don't walk on frozen lakes though because if the ice gives
way, it is beyond my control. Alternatives are simple to find and cheap so
why take a risk?

In article ,
"Ed Pawlowski" wrote:


I don't see not using a potentially hazardous material as being closed
minded.

You called me stupid, and when given an opportunity to retract the
label, you instead reaffirmed it. You based your assessment on the fact
that I see the risk of using PVC for compressed air as so miniscule as
to be negligible, while you see the risk as unacceptably large.

Each of our opinions are valid. To hold another as stupid because he
doesn't share your opinion, is pretty much the definition of closed
minded.

"Smitty Two" wrote in message
You called me stupid, and when given an opportunity to retract the
label, you instead reaffirmed it. You based your assessment on the fact
that I see the risk of using PVC for compressed air as so miniscule as
to be negligible, while you see the risk as unacceptably large.

Each of our opinions are valid. To hold another as stupid because he
doesn't share your opinion, is pretty much the definition of closed
minded.

You do have a point. You are not stupid, you just did one stupid thing.

Life is not without risk, but when you knowingly take the risk rather than
the readily available alternatives, well . . . . . . our opinions differ.

Smitty Two wrote:
In article ,
"Ed Pawlowski" wrote:

PVC is not allowed for air use.

If that's true, there's a few thousand machine shops who are breaking
some sort of rule. It's more or less the standard.

I agree. Every shop i've ever worked in has had pvc in some area or
another if not completely plumbed with it. Including my own. It works
fine.

steve

dpb wrote:
Smitty Two wrote:
...
Thanks for the link. I read it. I think the danger is highly
overstated. We've had the occasional blowout, but it's always been a
failed glue joint. It's loud and inconvenient, but hardly dangerous.
Of course, none of the thousand or so joints I've personally done have
ever failed, because I'm meticulous with them.
We've had at least a half dozen OSHA inspectors over the last 30
years. None of them squawked about our PVC air lines. I wonder what's
really up with that. Seems odd to me that PVC could be rated to 200
psi or so and then explode around 80 or 90. This strikes me as the
freak accident thing. The worst injury cited in your link was a broken
nose.
...

"PVC piping buried 3 feet underground at a Yakima manufacturing plant
exploded, opening up a crater approximately 4 feet deep by 3 feet
across."


i dare you to cite a link or document to support this ridiculous statement.