The Danger of Compression

General Properties of Gases:
Air under ordinary atmospheric conditions exerts a pressure of 15 pounds to the square inch. If, now, large quantities of air are compressed into a small space, the pressure exerted becomes correspondingly greater. If too much air is blown into a toy balloon, the balloon bursts because it cannot support the great pressure exerted by the compressed air within. What is true of air is true of all gases. Dangerous boiler explosions have occurred because the boiler walls were not strong enough to withstand the pressure of the steam (which is water in the form of gas). The pressure within the boilers of engines is frequently several hundred pounds to the square inch, and such a pressure needs a strong boiler.