Innovations 9 - 11 April 2000
BURNING METALS RESEARCH
BLANCH : A major research facility capable of producing a microgravity environment is being established at The University of Queensland. One of only five such ground based facilities in the world, the 30 metre microgravity drop tower will be built at the University's Mechanical Engineering Department and allows around two seconds of microgravity conditions per drop test. The facility may have a significant effect on research into burning metals. This is applicable into everyday medical and scuba diving operations when high levels of oxygen can cause metallic fires. According to Project Leader, Dr Ted Steinberg, the ability to conduct experiments in conditions of reduced or no gravity is of great interest to engineers and scientists as it allows tests in an environment, free of the effects of buoyancy or induced mixing. A combustion apparatus designed and built by Dr Steinberg's team is used to test the burning characteristics of a variety of metals such as iron, steel, aluminium and titanium. These experiments provide insights into the burning phenomena for metals used for many industrial applications including scuba systems, oxygen tanks, air separation plants, welding regulators and even several international space station components. A thorough knowledge of their potential flammability is vital to ensure human safety and safe operating conditions to exist within these systems. Dr Steinberg's talking now with Ron Drynan.
STEINBERG : The main point of the facility here is not actually the investigation of processes for application in space, it's to better understand things so that we can apply them here on earth. My specific area of interest is as I say in the area of metals combustion. The information we're gaining from burning metals in reduced gravity has applications, not just on a space station, but in air separation plants here in Australia, designers who design components that are going to work in oxygen systems, scuba gear manufacturers, very important application where there's a lot of fires occurring now in the scuba shops themselves when they're using inappropriate materials to fill the tanks. So our work has applications for scuba manufacturers to aircraft systems that contain oxygen, all aircrafts, civilian or military contain some to some degree an oxygen system and our work is directly contributing in making these systems safer as well.
DRYNAN : You talk about oxygen systems, is that different to an air system like we're breathing or are you talking about a super rich oxygen system?
STEINBERG : Essentially in an oxygen system we refer to an oxygen system as anything that's above atmosphere conditions, atmosphere conditions is about 21% oxygen, about 79% nitrogen. In an oxygen enriched system anything above 21% is what we would be considering and the reason we look at these systems separately than say air systems is, because as soon as you increase the oxygen content, things become far more flammable and we know say as you go from normal concentration of 21% up to 25 or even 30% oxygen, materials that would not burn in just plain air become highly flammable. For metallic materials if we increase the oxygen concentration enough up to its limit of course of pure oxygen, the metals themselves are actually burning very vigorously which is a concern because essentially you have a metal device containing the oxygen,so you have your fuel and your oxidiser right next to each other. If you have a very credible, and they exist in all of these systems, ignition source you're going to get that system burning and once you get the system burning it's very difficult to put it out because you have your fuel and your oxygen right next to each other.
DRYNAN : And the fires you mentioned in the scuba shops or the scuba refilling locations, what's the cause of those fires, anything common or is it individual events?
STEINBERG : It's typically due to using an inappropriate material in the presence of oxygen and what is happening is a lot of people are going and viewing these systems as not dangerous and therefore they're taking a material or a component that's not supposed to be used with oxygen, putting it on the oxygen system and then, say, they would open a valve or something and when you open a valve in a system like this, by compressing the gas that's contained, you can get very high temperatures generated. These high temperatures can then light a seal or a soft good which then would light the metallic material on fire and that's one such ignition scenario, so by using an inappropriate material on an oxygen system and doing nothing more than just opening up a valve or compressing the oxygen you can cause a very catastrophic event, very, very big fire.
DRYNAN : But how would that inappropriate material be involved in the oxygen transfer system?
STEINBERG : Well, simply somebody going down to a shop and buying the wrong component, it's essentially that simple. You should never use components that have oils on them in oxygen systems, yet we're finding a lot of people who have run these systems will go out, in scuba areas, will go out and grab a component, say and use oil on it because they're used to using oil and lubricants have a very important place in many systems but just not on oxygen systems, that's how some of the fires start. Now I don't want to give the impression that all scuba fillers are using inappropriate materials because that's just not true, majority of all of these people are using very appropriate devices and appropriate materials and appropriately compatible materials, so the applications of the knowledge we're gaining is essentially to develop better materials that will not support burning in these environments.
BLANCH : And that was Dr Ted Steinberg from the Mechanical Engineering Department at The University of Queensland.
