Many people probably use daily-life commodities with gas springs without even
knowing or thinking about it. Like many other things in our life, they are simply
there. Moreover, there are quite a lot of things that are intrinsically tied to gas as an
elastic medium. Maybe just in this moment you are actually sitting on a gas spring:
Your office chair, especially if it is a swivel chair, is most likely equipped with such
a system. In contrast to simple gas springs, like for example those used for the trunk
lid of your car, the gas spring in your swivel chair is a rather sophisticated suspension
system. Via a button or a lever, you have the possibility to allow the transfer of gas
between separate internal chambers. This feature provides the adjustment function
for the seat level, and you can easily adapt it to your body height—much easier than
with older mechanical spindle systems like those from, for example piano stools.
If you use gas as an elastic, suspending medium, basically you always take advantage of the equation of state for the ideal gas. However, since usually the suspension
motions are quick and allow little heat exchange, it is not possible to calculate with
an isothermal change of state but rather with the polytropic approach. It is among
others this special behavior of the gas which makes the respective spring characteristic disproportionately higher. Another advantage of gas springs is the just described
possibility of easy adjustment of the suspension level. This is especially favorable in
applications with different spring loads.