Fire sprinkler head - how to bleed air / disassemble?

Question

Had to drain my residential water system that has a sprinkler system with common recessed pendant heads. Need to turn water back on. I've seen instructions saying to bleed the air from the highest and farthest sprinkler head in the system. How, exactly, does one do this? Do you remove the head with a wrench? Maybe just loosen it? Or, perhaps, does the deflector turn or unscrew, allowing the stop valve to open partially? I just don't want to screw it up.

Also, I need to hang drywall on a ceiling in an unfinished room that has a pendant head with eschutcheon attached. What is the best practice for accomplishing this?

Answer 1

there should be some kind of test valve at the end of your run of sprinklers. It will be near the last one in the run and should have a pipe going to the outside somewhere or to a drain ....Do not mess with the sprinkler head itself , there will be black icky water in the pipe and it will make a mess. All of the sprinkler systems I have seen have some kind of ball valve or hose bib to bleed or test the system. As for the second question , the trim ring should pull off . Be gentle and don't hit the deflector on the head , then you measure side to side and end to end to find the center of the sprinkler and cut a hole in the drywall , big enough to slip over the sprinkler and still be hidden when the trim ring is put on.

Answer 2

I wouldn't worry about air in the sprinkler piping. The worst it can do is cause the alarm to ring on the worst of surges in the water pressure. You could cure this by increasing the retard time on the waterflow indicator. The cover comes off. An arm extends from the vane assembly inside the pipe. Moving this arm (sometimes up and sometimes down) starts the retard time. The switch will click at the end of the retard time. Adjustment is with the knob with numbers or letters on it.

You may want to raise or lower the sprinkler in the room you are finishing. If it is plastic pipe, this is a bit touchy. There are joining and gluing techniques that are important.

Unless you have a special wrench, loosening or removing the sprinkler is a bit chancy, especially with plastic pipe.

I would opt for the services of a knowledgeable sprinkler person for that.

Answer 3

The only valve you will find downstream the the system shut off valve would be an inspectors test connection and, seeing as how systems designed per NFPA 13D are not required to have alarms, I doubt you have an inspector's test connection.

I can assure you having air in the overhead pipe, most likely CPVC plastic, doesn't hurt a thing. The only reason we advise people to drain air off a system is to lesson the chance of a false alarm caused by water entering the system due to a surge in the city water supply system. But, given the small capacity of these systems, this wouldn't be a problem even if you did have a waterflow switch alarm.

Take my advice and just turn the water on.

I am certified NICET Level IV in sprinkler system design.

Answer 4

Pulled of a piece of baseboard and there had been a nail in our sprinkler system line since we were built in 1999. Caused a huge mess of course which was compounded by a broken main shut off. Had a nice chat with the fire department who had to come turn off the water. Long story short, plumbers wouldn t touch the fire line and had to get the nice folks and VSC here in Northern VA to come fix the PVC pipe. That s all it is. Fancy colored PVC pipe. I asked him about air in the lines and he said to not worry about it.