Over the last few years we have seen many dry systems reaching their age limit and rotting out here in Alaska. When these systems were originally installed the fire codes allowed the use of thin wall black pipe (non galvanized), as time passes, water in the form of condensation or residual water from trip testing the dry system and oxygen combine to form an acid, this is how corrosion and rust are formed and why a wet system can use non galvanized pipe and dry systems can not.
As this carbonic acid eats away at the thin wall pipe it not only creates pin holes (leaks in your system, ever notice how often your air compressor kicks on?) but it also causes an EXCESSIVE buildup of sediment. This buildup can be so bad that it will render the sprinkler system useless.
This sprinkler head is completely plugged and would probably have failed to flow water in the event of a fire.
The picture to the left shows just some of the sediment that was collected from this same system. This system was so bad that our hoses often plugged while flushing due to all the corrosion and sediment.
This is why the NFPA requires a dry system to be tested for this every 5 years.
If you have a dry system and would like to have it tested for sediment contact us.