Special care is needed when working with acetylene because it is highly unstable:
• Never use acetylene at a pressure above 15 psig. Acetylene is stored at moderately high pressures in specially constructed cylinders that contain a porous filler material. The material has minute cellular spaces to prevent "free" acetylene from collecting in pockets of appreciable size. The porous mass is wetted with acetone in which acetylene is then dissolved. The combination of porous filler and acetone allows the acetylene to be safely contained in the cylinder at 250 psig and 70°F (21°C). Withdrawl rate from gas cylinders shall not exceed manufacturers recommendations.
• Never allow the temperature of any part of the acetylene system to rise above 130°F (54°C).
• Never use an acetylene cylinder on its side. Keep it upright and chained to a cylinder truck, wall, or other safe, stable object so that it cannot be knocked over or otherwise damaged.
Acetylene should not be used in fuel-gas systems or pipelines made of copper or of copper-based alloys containing more than 67 percent copper, or when the gases may come in contact with silver-bearing materials such as those used in silver brazed pipeline joint. This precaution applies only to piping system, not to brass hose connections, torches, and tips.
Acetylene and acetylene-based chemicals can combine with copper or silver and form explosive acetylene compounds if they are in contact with the high-copper or silver alloys for a long time in the presence of moisture. Such compounds can explode if subjected to heat or mechanical shock.
Artificial odors are added to natural gas, propane, and propylene so that a leak can easily be detected. The gases can be smelled in concentrations of about one-fifth their lower explosive limit, a safety factor sufficient to allow the problem to be corrected.
Acetylene has a natural, pungently sweet odor and can be detected in air at a concentration of about half of its lower explosive limit. When acetylene is smelled, quick action is required. |
