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Extend the Life of Your Gas Springs

Gas springs are pneumatic cylinders of heavy-gauge steel that hold pressurized nitrogen gas. A nitrite- or chrome-coated steel shaft with a seal on one end extends out from the cylinder. If you push on the shaft, it will collapse in on itself, and then the strength of the pressurized air on the inside will push back. If you pull on the shaft, it will extend outward, then pull back in as the vacuum created by your pull fights against the force of your hands. Depending on the cylinder and shaft diameters, the sealed kind of gas springs generally come with initial internal pressures between 5 lbs and 450 lbs.

Some variations (which use natural atmosphere rather than nitrogen) have a small hole on the far end of the cylinder that allows air to flow slowly into or out of the cylinder — thus creating a mechanism by which pressure on the gas spring is first fought by the pressure created inside the cylinder, then slowly released as the pressure inside equalizes with the pressure outside through the small hole.

If you want your gas springs to keep functioning for as long as possible, you want to minimize stroke (the distance the shaft has to travel) and maximize gas volume (the pressure inside the cylinder). You also want the end connectors — generally ball-and-socket joints to protect the gas springs from experiencing torque-induced load — to be strong enough to withstand both tensile and compressive loading. (The cheaper flat connector with a hole that creates a hinge joint is awful for your gas springs’ life as it has no ability to relieve stress from out-of-plane movements.)

The best placement for the gas spring has the shaft pointing down (and correspondingly the cylinder pointed up.) This is because the spring passes through a thin layer of oil at the end of it’s complete stroke to keep it lubricated, and the shaft-down orientation ensures the oil is gathered in one place to present maximum effectiveness at lubricating the spring.

Finally, keep the gas springs within the temperature limits recommended by the manufacturer. Over-hot springs allow gas to escape by increasing the pressure of the gas inside the spring (and remember that we’ve already chosen to maximize the internal pressure in order to improve spring life, so increasing it even more will cause problems), and over-cold springs allow gas to escape by causing shrinkage of the seal that holds the gas in.

Stick with these guidelines, and your gas springs will last for decades.

Pneumatic Fittings In Everyday Life

Most often when we think about a factory that fabricates products like our cars, coffee grinders, and computer boards, we envision a robotic environment where dozens of computerized arms whirr on electric motors, bustling efficiently about creating product. Truth be told, that vision is often wrong in a few way. For one thing, ‘arms’ aren’t nearly as prevalent as you might think. For another, most of the power in fabrication labs these days comes from pneumatics, not from electric motors. The sound in a plant is much less ‘whirr, whirr’ and much more ‘psshh, hiss’.

But it’s not just in the fabrication plant that we come across pneumatics. A surprising amount of everyday objects use pneumatics to get their jobs done. Most jackhammers must be attached to an external air compressor via a pneumatic fitting, for example. Many larger trucks and buses have pneumatic brakes. But what about in your daily life?

How about:

  • Tire pressure gauges
  • Vacuum cleaners
  • Some nail guns
  • Bicycle/ball pumps
  • The device that slows your screen door down so it doesn’t slam shut when you let go of it
  • The handicapped-access button that opens door for you
  • Some car’s shocks
  • Those capsules you use to give and receive money from the farther-away of the two bank teller drive-ups

The list is long and sometimes surprising. There are far and away more industrial applications than household ones for pneumatics, of course: pneumatics see use in almost every kind of factory, whether they’re fabricating DVDs or deburring cast metal tools before they’re ready for sale. The most common difference between industrial and home-use pneumatics is the likelihood that a given tool will be self-powered or be required to hook to a central pneumatic compressor that provides power to a variety of different units.

Thus, while pneumatics might be common in everyday life, you rarely see pneumatic fittings outside of industrial applications. Unless you happen to have or use a sandblaster, air compressor, or vacuum pump for craft projects or as a part of the work you do from home, chances are much greater that you’ll come across a hydraulic fitting at home than a pneumatic one.