Flushing debris from fire sprinkler lines.
I have seen the results of this method and it seems to provide a more thorough cleaning than the hydraulic method.
See NFPA 25 2008 Handbook, Section D.5.4
(Which by the way works great and has saved our bacon several times for tenant improvements and the Central recalls.)
However that is not what I am looking for, the unit we require injects water into the fire sprinkler system under air pressure creating a pressure surge that flushes debris (Mic) from the fire sprinkler branch lines pack to a discharge point usually the valve. I have seen a dry system installed in a mine that was flushed using this technique and it appeared to do a far superior job to just hydraulic flushing.
I talked to a gentleman yesterday about hydropnuematic flushing. They made their own machine, using the picture in NFPA 13 as a guide.
The machine was made from an air compressor with the compressor removed. A fitting were welded on the top of the tank for a compresor connection. Garden hose fittings were welded lower on the tank. The end of pipe fitting was removed from the pipe and a garden hose fitting and a shut off valve was installed. NFPA 25 2011 Edition, Fig D.5.4a shows the machine. Hydro testing the machine prior to use would be a good idea.
The main control valve was shut and the main drain was opened. The clapper was was removed or latched open. The end of line valve was opened and 100 PSI of air was pumped into the lower tank. The water under pressure removed the rust and scale from 10 pipes at a time. Amazing what one can learn by attending a class.
We have flushed a couple of systems using garden hoses, not backflushing. We ran the hoses outside. We have found 1", 1.25' and 1.5" pipes plugged solid with rust. We have also found you need to make the customer aware that when you remove the rust and scale, you may develope large enought leaks to soak through sheet rock and tile very quickly. Have plastic sheeting ready to cover equipment.
You should have pipe, fittings and the equipment ready to machine pipe as needed. Make sure your contract protects you against leaking pipe.
We paint the ends of the flushed and/or replaced pipe with white paint. We then use a magic marker to write the date,company name, and what we did on the fresh paint.
This is just a concern or opinion, nothing more, as I have no experience with "hydropneumatic flushing". If the piping one is dealing with however includes any exposed polyvinyl chloride pipe, introducing 100 psi air into same and propelling slugs of water or whatever driven by same sounds like an accident waiting to happen.
We have used similar techniques for flushing various process lines (not sprinkler piping). We use a small compressor to charge a pressure vessel to the desired pressure. The pressure vessel is then connected to the piping system with a valve. When ready to flush, the valve is opened and adjusted to control the flow of air into the pipeline.
Agree with fireguy too. Using compressed air can always be hazardous and close attention is needed with regard to the pressures used.
Thanks to all that have responded,
We tried the Hydraulic method but the accumulation is so compacted that it will not move from the bottom of the piping, 80 PSI was flow through the system utilizing 1.5" and 2.5" hoses and it is still showing approximately 25% blockage. Technicians managed to fill two burlap bags before getting "clean" water to discharge from the Hose Monsters!
This System was installed in 1953 and it seems that not much has changed since then, might be time for a new system as their are several other factors affecting this particular installation.
I do wish this issue was better addressed by the standard as this is the third dry system so far this year that we have found plugged! Why is this not identified as a system impairement in the 2011 edition of NFPA 25?
