On 9/10/2012 5:50, RogerN wrote: I've seen a few of the suppliers that
sell torches for glassblowing also
sell oxygen concentrators so you can run the torches without having
to buy
oxygen in tanks. I'm wondering if this would be beneficial to
metalworkers
that do a lot of torch work.

http://www.sundanceglass.com/oxygen-concentrator.htm

They have 7PSI 5LPM for $275. This may be OK for oxy/acetylene
welding but
not enough pressure (or volume) for cutting. So what about adapting
an oil
free compressor and a tank to give you enough pressure and volume for
cutting torch operation. Seems this price is getting competitive
with the
price of tank and contents, or at least by the time you have to get a
couple
of refills.

Normal air compressor at 10bar has already 2.1bar of oxygen in
the tank.. It is just the partial pressure that matters.

It would be nice to find a high pressure compressor compatible with
oxygen
to fill my own tanks. I priced a small 1/2HP oxygen compressor that
went to
2200PSI for tank filling, the price was almost $5000 for the compressor.
Anyone know of an affordable safe way to boost ~5PSI from an oxygen
concentrator to high enough pressure to be useful for a cutting torch or
even to fill an oxygen tank?

Pressure booster is the name.. Pneumatic version uses a big
area cylinder to push a small-diameter high-pressure cylinder..
Push-pull usually so the big one has two smaller cylinders
at both sides with the stem output from both sides. Then
just some one-way valves and an oscillator with the big
cylinder, and there you go.. Available at ebay sometimes used.

Used diving bottle filling compressors would be another way to go.
If they compress air to 200bar, they handle oxygen partial pressure
of 42bar at output. It is the same whether there is only 42bar oxygen
or air at 200bar.


Propably the cheapest and metalworking way is to build it
yourself from a few pneumatic cylinders.. If you keep the
oxygen pressure low (like less than 40bar), there is IMHO no
need for any special cleanliness. Use compressed air for
operating the driver cylinders, and oxygen enriched air from
the concentrator for the compressing cylinders. The cylinder
stems could be used for triggering limit switches, operating
the oscillator action. Really rather simple. One-way valves
could be swagelok or such quite cheap components.

Kristian Ukkonen.