Originally Posted by riosanjuan
What in the world are these people talking about when they say that oxygen concentrators need to be converted for lampwork use?
Oxygen concentrators don't need
to be converted for lampwork. Some are, though, and I'll explain what, how, and why.
Oxygen concentrators (also called generators) come in various sizes and packages. Some are used in the health care and some are used for industrial applications. When given a similar output (in terms of volume and delivery pressure, and I'll discuss that in more detail below), the biggest difference between a unit sold for health care and a unit sold for an industrial application is the packaging and sound proofing. Medical units can be used for industrial applications, but industrial units cannot be used for medical applications.
Units sold for home or hospital use tend to have easy-to-clean plastic cabinets that have sound reducing insulation built into them, because they are intended to be run next to a person for long stretches of time. Some also have bacteria filters in-line. They also tend to have alarms that sound when flow is interrupted, and most shut themselves off when that happens.
Units sold for industrial applications tend to be housed in metal cabinets (but not always) and some of the very large units do not have a self-contained compressor and require a separate air compressor, dryer, and oil filter (if the air compressor is not oilless). Sound reduction is not an important concern in many of these machines, so they are sometimes louder than their health-care counterparts. They may or may not have an alarm that sounds when flow is blocked, and most will shut themselves off if there is a blockage in flow. Some of the industrial units have better compressors in them than the health care units.
For most lampworking studios, metal cabinets are not a necessity and the associated noise is not always welcomed. The easy to clean, insulated, plastic cabinets are a good choice.
One example of a machine converted to lampworking use is the Regalia. The Regalia is based on the medical IntegraEZ (formerly Integra10). Paulette, from whom I inherited my business, had been selling the Integra10 (a medical machine, contrary to what you might read on a certain glass supplier's site) for lampworking and asked SeQual if they could make a machine that would be easier to use for lampworking. The Regalia was their response. It is built with the tough industrial compressor, has a non-medical software package (does not alarm and shut off when flow is blocked, so you can shut off your oxygen valve at the torch without worry), and is housed in the easy to clean, insulated plastic cabinet (so it is quiet and can run right next to you if you want). SeQual makes other industrial units, but they would be better suited for larger production shops.
Now back to the output. The output of these machines is expressed in terms of flow - the volume produced in a given span of time, usually in liters per minute (LPM) or cubic feet per hour (CFH) - and static pressure (the push behind the flow when you block it, which is different than working or running pressure) measured in pounds per square inch (psi).
When torch manufacturers list the requirements for their torches, they will list out their recommended psi setting. This is not for concentrators. This is what setting you would need to set an oxygen regulator on a tank of oxygen to in order for it to provide the flow (LPM) needed for the torch.
A machine that claims to put out 20 psi may or may not be big enough to feed a torch because that number alone does not tell you the volume of oxygen getting through to the torch. You have to consider the LPM rating, and that is the more important measurement. Some torches do require a little more push behind the flow to get the oxygen through internal restrictions, but even then, they still need adequate flow for the torch to perform well.
Some companies, however, seeing the manufacturers' psi recommendations, but not understanding torches and their needs, have taken machines and changed the output psi to a higher setting. In some cases, the LPM output is also changed. For example, some of the machines out there are made from a used base unit that was designed to put out 5 LPM at ~5 psi. They then modify the machine and boost the psi setting to 15 and change the LPM rating of the machine to 8 LPM. I do not know how extensively the machine is modified beyond that (i.e., are the other components of the machine such as wiring and switches and the compressor and the sieve and all that rated to work together for that kind of output?).
There are machines out there that were originally designed by actual concentrator manufacturers to put out 20 psi (and with 10 LPM, which is adequate flow for most bead torches and the centerfires of larger torches), so altering smaller individual machines to put out 8-10 LPM and 15-20 psi is not necessary. These unaltered high-output machines may be a little more expensive (not much more for the used machines), but you get what you pay for - a machine that was originally designed by engineers and technicians to put out what it puts out.
For large torches that require more flow and more pressure, there is also the option of a pressure boosting system, like the HVLPO2. This system takes regular concentrators, gangs them together, collects their oxygen, and boosts the output pressure (outside of the machines, so it does not alter the machines). This system isn't so converting the individual machines themselves for lampworking, but is taking the practice of ganging machines together and making it work better for certain lampworking set-ups.