Oxy/Act welding setup safety

I am adding two regulators to my welding system for welding aircraft
parts with a little Smith Airline torch system.

I was able to but two excellent new Craftsman acetalene regulator ver
y cheaply.

I am going to add these regulators to my little portable welding table
and rig my hoses from the tanks to these regulators.

I'll step down the oxy to app. 50 lbs. pressure to make a dual stage
system.

I am planning to step down the acet to 15 lbs as the accepted maximum
for delivering acet gas from a cylinder. I'm worried 15 lbs might be
too low to properly utilize the second regulator and hold accurate
pressure and flow for OA welding.

Can I step down the first regulator to feed the second regulator to
say 50 lbs as long as I always flow at low volumes under 15 lbs from
the second regulator?

The second step will be only for low flow 3-6 lb welding torch
settings. Anything higher in flow or pressure will be run on the
primary regulators as usual.

I've seen banked systems in the big heavy equipment shops from my
early trade but never really studied the systems. They consisted of
many tanks piped through big regulators to supply pipe then stepped
down at work stations.

On Jun 18, 5:34*pm, canuck_bob wrote:

I am planning to step down the acet to 15 lbs as the accepted maximum
for delivering acet gas from a cylinder. *I'm worried 15 lbs might be
too low to properly utilize the second regulator and hold accurate
pressure and flow for OA welding.

I did the same thing with O2 regulators years ago for a home built O2
re breather. I needed the second stage because when the tank got low
the regulated pressure went way up and wasted gas. Setting the first
stage at 15 psi and the second at 3-5 worked great and about doubled
the time before the pressure spiked.

IMHO it should work just as well for keeping your acetylene pressures
stable.
===========================
Leon - DragerSorb - McAtee

"canuck_bob" wrote in message
...
I am adding two regulators to my welding system for welding aircraft
parts with a little Smith Airline torch system.

I was able to but two excellent new Craftsman acetalene regulator ver
y cheaply.

I am going to add these regulators to my little portable welding table
and rig my hoses from the tanks to these regulators.

I'll step down the oxy to app. 50 lbs. pressure to make a dual stage
system.

I am planning to step down the acet to 15 lbs as the accepted maximum
for delivering acet gas from a cylinder. I'm worried 15 lbs might be
too low to properly utilize the second regulator and hold accurate
pressure and flow for OA welding.

Can I step down the first regulator to feed the second regulator to
say 50 lbs as long as I always flow at low volumes under 15 lbs from
the second regulator?

The second step will be only for low flow 3-6 lb welding torch
settings. Anything higher in flow or pressure will be run on the
primary regulators as usual.

I've seen banked systems in the big heavy equipment shops from my
early trade but never really studied the systems. They consisted of
many tanks piped through big regulators to supply pipe then stepped
down at work stations.



What do you hope to gain by a two-stage system?

On Jun 18, 1:34*pm, canuck_bob wrote:
I am adding two regulators to my welding system for welding aircraft
parts with a little Smith Airline torch system.

I was able to but two excellent new Craftsman acetalene regulator ver
y cheaply.

I am going to add these regulators to my little portable welding table
and rig my hoses from the tanks to these regulators.

I'll step down the oxy to app. 50 lbs. pressure to make a dual stage
system.

I am planning to step down the acet to 15 lbs as the accepted maximum
for delivering acet gas from a cylinder. *I'm worried 15 lbs might be
too low to properly utilize the second regulator and hold accurate
pressure and flow for OA welding.

Can I step down the first regulator to feed the second regulator to
say 50 lbs as long as I always flow at low volumes under 15 lbs from
the second regulator?

The second step will be only for low flow 3-6 lb welding torch
settings. *Anything higher in flow or pressure will be run on the
primary regulators as usual.

I've seen banked systems in the big heavy equipment shops from my
early trade but never really studied the systems. *They consisted of
many tanks piped through big regulators to supply pipe then stepped
down at work stations.

You're probably in Canada but in the US you need: Compressed Gas
Association Pamphlet G-1.3-1959
according to: http://www.osha.gov/pls/oshaweb/owad...able=standards
Karl

On Jun 18, 11:50*pm, "Tim" wrote:

What do you hope to gain by a two-stage system?

Probably flame stability. When small tanks (any tank actually but is
more noticeable with small tanks) get low the high side pressure
changes by a greater % for a given amount of gas used resulting in
increased low side pressure creep. For a quick tack it's not
noticeable. Over a longer welding project the pressure will change
enough that you need to re-balance the flame. This is one of the
reasons 2 stage regulators are sold.

When setting up a paint booth air system it is a good idea to use 2
stage regulation to insure constant pressure at the gun for the same
reason.
===============
Leon McAtee

Exactly, my smaller home tanks are great but my neutral flame setting
wanders a bit while welding. It tends to a slight oxidizing direction
which isn't as noticeable as a carburizing creep. Right now I
maintain a hint of a feather but would prefer my system would hold
settings for the length of a cluster. With thin stuff it gets a
little harder to weld because of the wandering heat as well.

With the oxy it seems like I can feel the pulsating effect of the
regulators diaghram. I'm probably way off but its like a faint
pulsing action that changes the heat on thin stuff. I'm preparing to
weld real thin coupons for training and heat control is a real skill
with the .025 stuff. I would like to know I can weld thin tubing with
finesse before tackling a fuselage. Besides practicing with an OA
torch is fun. No humming, smoke, and wire spools or rods and thier
toxic fumes and stink. Just fire and liquid steel, one sings the
other smiles when thier happy, my kinda meditation!

Link above lead me to a number of good sites. I will stick to 15 lbs
because it was noted in a number of places that the Acet regulators
are designed to function at these low pressures.

The info on tank manifolds did indicate that free Acet at higher
pressures was common in a proper designed manifold but why mess around
if its not needed.

One thing for sure, 15 lbs is the max out of the regulator to the
torch. If it flows at substantial rates the gas is very unstable.

On Fri, 19 Jun 2009 10:37:26 -0700 (PDT), canuck_bob
wrote:

Exactly, my smaller home tanks are great but my neutral flame setting
wanders a bit while welding. It tends to a slight oxidizing direction
which isn't as noticeable as a carburizing creep. Right now I
maintain a hint of a feather but would prefer my system would hold
settings for the length of a cluster. With thin stuff it gets a
little harder to weld because of the wandering heat as well.

bloody hell. everyone gets it. I thought it was just me.
used to drive me nuts until I gave up.