Is getting fired making you feel badly about being told to leave your job?
Fire extinguishers don’t normally expire, but some do need recharging occasionally. However, some professionals routinely start replacing or recharging extinguishers after about 7 years of service as a preventive measure. This is why OSHA’s Fire Prevention standard requires all fire extinguishers to be inspected annually by someone trained to do that inspection. Most practices have their fire extinguishers inspected yearly by a safety company, which places month and year inspection tags on each extinguisher. The average cost for this service is only a few dollars per extinguisher.
Lots of ways to do it! Use your imagination. All you have to do is make sure that you cushion the impact on the egg. I did this with my class and we had everything from styrofoam to peanut butter. (I don't recommend that though).
Fire extinguishers should NEVER be used as a toy. Yours, an ammonium phosphate base, is basically the same as fertilizer, and can be extremely dangerous; this is a corrosive compound, and dangerous to anyone coming into contact with it. I strongly urge you to find a safer method to vent your spleens.
