Aluminum Extrusion: Staying Cool with Nitrogen

Aluminum is a highly malleable material, which is readily shaped for any number of purposes. The aluminum extrusion process is key to shaping aluminum, and it must be completed in an inert environment to reduce the formation of oxides. Learn why this is important and how facilities can reduce the risks of health hazards in an inert environment. 

How Aluminum Extrusion Works

Billets of aluminum are first heated to above 800 degrees Fahrenheit to become malleable, then coated with a lubricant so the molten metal will not stick to the extruding ram. 

The ram presses the aluminum billet through a die, which is cast in a given shape. As the aluminum passes through the die, liquid nitrogen flows over the metal to prevent oxides from adhering to the aluminum. This also extends the lifespan of the die by cooling it. In some operations, nitrogen gas is used instead of liquid. While the overall purpose is the same -- to keep out oxides, which can cause the extruded aluminum to crack -- the gas does not cool the die. 

The shaped aluminum passes through the die, then exits the press where its temperature is taken. Temperature records help maintain press speeds, for plant efficiency. The extruded aluminum pieces are then transferred to a leadout table and a puller, where the metal is cooled using fans. Some mixtures of aluminum are cooled with water as well as air. 

The cooled and cut aluminum is then stretched via a stretcher, a step that increases the hardness and strength of the finished piece. Finally, extruded aluminum pieces are cut for precision and aged under controlled temperatures via heat treatment. 

The entire process resembles a play-doh modeling kit, where the dough is squeezed through a press and comes out in a tube or a star shape, for instance. 

Extruded aluminum pieces are used in a variety of industries, including railway cars, lightweight automobiles, bridge decking, solar panels, and coaxial cables. 

Whether liquid or gaseous nitrogen is used, there is a risk of a nitrogen leak causing an oxygen deficient atmosphere. Nitrogen is naturally heavier than oxygen, so it displaces the oxygen molecules in the atmosphere. Since nitrogen has no color, odor, or scent, employees are unable to tell there's a leak. A leak poses health hazards in addition to work disruption and revenue losses. Fortunately, there's an easy way to protect facility staff. 

Why Oxygen Sensors Should Be Used With Aluminum Extrusion 

When nitrogen displaces oxygen, oxygen levels start to fall unbeknownst to anyone present. Eventually, oxygen levels will grow dangerously low. In an oxygen deficient environment, employees may start to feel dizzy or confused. Some may sweat, start to cough, or experience rapid breathing and increased heart rate. Death via asphyxiation is a real risk. 

An oxygen sensor provides assurance that there is no leak, since it tracks levels of oxygen in the room 24/7. As long as oxygen levels are above the OSHA threshold of 19.5, the monitor will be silent. If liquid or gas nitrogen starts to leak, leading oxygen levels to fall, the monitor will sound an air horn and flash lights. Staff will understand there is a problem and will have time to evacuate to safety. Staff can also check the monitor face at any time to see oxygen levels at a glance. 

PureAire offers oxygen monitors that feature zirconium sensors, which last long and withstand shifts in barometric pressure and temperature. These monitors can operate for over 10 years with no annual maintenance or calibration. PureAire's monitors work in temperatures from -40 Celsius to 55 Celsius and even function in confined spaces, such as basements or freezers.  Learn more about PureAire's products at www.pureairemonitoring.com. 

The Overview on Inert Glove Boxes and How They Work

For businesses that work with inert gases or hazardous materials, glove boxes are essential. They allow employees to safely work with sensitive or hazardous materials without compromising either the material or their safety. While glove boxes are an effective solution to handling inert and hazardous materials, they are not failsafe. To ensure there are no leaks in the glove box, it's critical to pair a glove box with an oxygen monitor. 

How a Glove Box Works 

A glove box, sometimes known as a dry box, is a large box with at least one window and two ports. The ports allow workers wearing arm-length gloves to place their hands inside the inert environment, where they can work with hazardous materials or inert gases, such as argon or nitrogen. 

The interior of the glove box is filled with an inert gas -- usually nitrogen, although it could be argon or helium if the materials used inside the box react with nitrogen. While the glove box environment is intended to be closed, small amounts of oxygen can seep through the glove ports. Thus, it's essential that the glove box be purged nightly. 

There's an antechamber on one side of the glove box. This allows you to place materials in the chamber, then open the interior door and bring them into the glove box environment. To prevent the insert gas inside from seeping out through the antechamber, you must never have both the interior and exterior door open at the same time. 

Inert gases, such as nitrogen and argon, displace oxygen. If these gases were to leak into the air via the antechamber doors or through a hole in a defective glove box, it would push oxygen out of the room. Oxygen levels would begin to drop, eventually falling below the OSHA threshold. 

When oxygen levels drop below the OSHA threshold, it can cause respiratory and cognitive problems, as well as death via asphyxiation. To protect employee safety in a glove box environment, it's critical to use oxygen monitors onsite. 

How an Oxygen Monitor Protects Your Workers 

While your staff might see the antechamber doors open and understand that a leak has occurred, most leaks are undetectable until it is too late. 

Inert gases have no color or odor, so there is no way for someone working onsite to know at a glance or sniff there's been a leak. Meanwhile, the air in the room would slowly lose oxygen, eventually leading to an oxygen deficient environment that places your employees at risk of death by asphyxiation. 

A wall-mounted oxygen monitor samples room air 24/7. The monitor remains silent if there's sufficient air in the room. If there is a leak of nitrogen, for example, and oxygen levels fall, the monitor will sound an alarm and flash lights, so workers can see and hear there is a problem. 

Your employees will be able to leave the room before suffering adverse health effects. Staff will also be able to complete shifts with less stress when they know the environment is safe, because they trust the oxygen monitor is working properly. 

PureAire's oxygen monitors feature long-lasting zirconium sensors. Once installed, these oxygen monitors measure the oxygen in the air for 10 or more years, without needing annual calibration or maintenance. The monitors are unaffected by sudden shifts in barometric pressure or thunderstorms. The digital display provides legible, updated oxygen readings so employees can check ambient oxygen levels. PureAire's oxygen monitors can be used in confined spaces and in temperature extremes as low as -40 Celsius. All PureAire oxygen monitors come with a three year warranty for your protection. Review specifications or learn more about oxygen monitors from PureAire by visiting www.pureairemonitoring.com