Central sprinklers slipping seats seeping suspiciously

[RainbowFS]

Sorry for the tongue twister.
This is more of a field observation and I'm curious whether anyone else has encountered a similar problem.

Focus- systems built from the late '80's into the '90's and equipped with Central/Gem with Belleville (brass cup) seats.

Back story-
I'm sure most on here remember the nightmare that was Central's call-it-anything-but-a-recall recall of O-ring style heads. During that same period the non-recall heads with Belleville seats went through a number of redesigns as well, presumably in a effort to find an effective, durable design. It seems that some of those designs were better than others.

My story-
We're finding sprinkler heads of this age with seats that have slipped ever so slightly off and allowing a tiny bit of water to seep out. The specific conditions are always consistent:
1. The heads are always Central, Gem, or other heads made under that corporate umbrella in the the years mentioned before.
2. High water pressure in the system, either from a pump or just crazy high city pressure, in excess of 120 psi.
3. The cup that the glass bulb rides in is much shallower than more recent heads, looking more like a section of a ball than current ones that are shaped more like a shot glass.
4. The slippage is very gradual. Early on it's likely that the seepage (from uprights) will evaporate before enough can collect on the bottom of the fitting to actually drip off. If one can get close enough, streaks of rust or paint discoloration will be visible. Pendent heads will develop a green or black streak on the frame or the deflector.
5. When it does start actively dripping on the floor it becomes obvious why once a close look is possible.

In the past five years I've probably ran into this a half a dozen times. Some systems had over 60% of the heads seeping to varying degrees.

Has anyone else had to deal with this type of thing?

Alex Traw
Rainbow Fire Sprinklers
Albany, Oregon

 

[cdafd]

not sure if the same thing but had a grocery store, and do not remember the make of the sprinklers, about three years ago.

a lot of the sprinklers in the store had a green mineral type build up on them. I forgot what the term was for it.

All the heads were replaced. no fire pump invovled

 

[cdafd]

found some paperwork, appears they may have been central sprinklers with an o ring, they were recalled sprinklers

 

[Sprinklerfitter]

In a similar situation right now,

Old manufacturing warehouse converted into a college campus in the late 80's, an entire wing utilized Gem concealed sprinklers. To date we have changed about 25% of the heads do to leakage and identified another 50 heads during the last annual, some of the sprinklers were so corroded that the cover plate was stuck to the deflector. I will look into the exact model number but I am certain they were not part of the Central recall. How do you post pictures?

Jamey

 

[AZsprink]

From my experience, the recalled sprinklers were glass bulb, and the bulb sat flush to the seat, and the seat sat flush to the bottom of orifice. I would check to see if the model in question was part of the recall. I have also seen some copper systems that had so much flux present, that maybe the flux corroded the seats? One time I fixed a leaks on a steel shed type building, that overpressured in the summer 300+ PSI I installed pressure relief valve, and new heads. I have replaced a lot of the recalled GB heads that had lots of green fluffy corrosion around seat.

 

[RainbowFS]

I stated in my post the difference between the O-ring heads (recalled) and the Belleville style brass on brass seat (not recalled).

The neoprene O-ring would swell when exposed to oil (as in thread cutting oil)and cause the seat to not fall out when the fusible link broke, hence the recall.

I'm referring to Central/Gem heads of that same period that were not recalled. We're finding situations like I wrote above more ad more.

Alex Traw
Rainbow Fire Sprinklers
Albany, Oregon

 

[Sprinklerfitter]

I reviewed the project file, it is the Gem model F976 we are having issues with.
Jamey