Acetylene is a well known fuel gas that is used almost universally in gas welding.

Although it is very common, acetylene gas is an extremely dangerous material.

Acetylene gas is a compressed gas made up of carbon and hydrogen.  If it is not stored or used properly, compressed gas can lead to serious fires, explosions or releases due to pressure buildup in cylinders or reaction to other materials.  It is extremely important that employees and other handlers understand and follow proper procedures for storing and handling compressed gases.

Acetylene is so reactive, it should never be allowed to to come into contact with metals such as unalloyed copper.  It should not be stored or used at pressures greater than 15 psi (pounds per square inch).  Cylinder pressures are rated for 250 psi but this is acceptable because the gas is dissolved in acetone. 

The National Electric Code has a special designation for using electrical equipment around acetylene because is so flammable.  There is no other substance that falls into this classification!  Acetylene leaks, no matter how small can have very serious consequences.  It has the widest explosive range of any commonly used gas when mixed with air.  The explosive range is from 2.5% to 82%. 

It is important to teach and use proper procedures when using acetylene gas. 

  • Close the cylinder valve before shutting off the regulator.  This will permit the gas to bleed from the regulator.
  • Always close the valves on empty cylinders when returning for refills or putting into storage.  Even though the gas has been used up, there is still flammable acetone left in the cylinders that can evaporate into the air and create its own dangers.  Acetylene gas is lighter than air so any leaking should gas rise but occasionally certain atmospheric conditions can prevent it from rising because it is only slightly lighter.
  • Never store acetylene cylinders near open flames or electrical equipment. 
  • Acetylene cylinders should be used and stored in an upright position only to avoid the possibility of the acetone leaking from the cylinder.  If this isn't possible and the cylinder has been laying down, place the cylinder upright and let it stand for at least thirty minutes before using.  This will help prevent liquid acetone from running into the regulator.  Even though they might seem to be, acetylene cylinders are not hollow   They are packed with a porous rock that is saturated with acetone.  OSHA regulations state that all cylinders must be stored with the valve end up. 
  • Always use acetylene in a well vented area. 
  • Cylinders containing acetylene should never be taken into a small or confined space.
  • Never store acetylene, or any other fuel gas, within 25 feet of oxygen cylinders.  If this isn't possible, it is important to have a noncombustible partition separating the two gases when storing.  This partition should be 1/2-hour fire rated and at least five feet high.
  • Always cap and secure stored cylinders upright to prevent them from falling over and damaging the valve or the cylinder itself. 

It is extremely important to train all employees using acetylene gas in the proper use and storage of acetylene.