They are setting up two simulated rooms at the Philadelphia Fire Academy and they plan to torch them both, with flames raging at 1000 degrees.
One room will be equipped with sprinklers, one will not. The people who attend this weekend's annual event, will see the difference.
"Then you see the actuation of the sprinklers and that sprinkler suppresses the fire. You see the value right away, it's a side by side demonstration," said Commissioner Lloyd Ayers.
The show raises money for the Fireman's Hall Museum as well as fire prevention.
There will also be a fire hose target competition between firefighters.
Last year, the muster raised $12,000, half of which went to the department's Free Smoke Detector Program.
Fire officials would like to think that played a big role in the fact that the city recorded its fewest fire deaths last year at only 25.
"Sixty to 70 percent of those folks that die in fires, don't have smoke alarms or their batteries or gone and missing," said Commissioner Ayers.
Commissioners Ayers implored me to show our viewers what to do if you wake up and your house is on fire - in their smoke trailer, which will be at the muster.
The non-toxic smoke inside gives children a sense of what it would be like.
Roll out of bed, crawl, check the door for heat, and if it is hot, head for a window and call for help.
The muster is Sunday from 9:00 a.m. to 4:00 p.m.
Admission and parking are free. Food and drink will be available for purchase.