February 8, 2016
Loss of Color in Glass Bulb
"When the bulb loses it's color, is that an impairment?"
We have reviewed NFPA 25, 2014 edition as the applicable standard. Our
informal interpretation is that the loss of color in the bulb does not affect
the operation of the sprinkler and allows it to remain in service.
The requirement for inspecting sprinklers is Section 5.2.1.1 where sprinklers
shall be inspected from the floor level annually. The criteria for the
inspection is Section 5.2.1.1.2 that identifies that any sprinkler that shows
signs of leakage, corrosion, physical damage, loss of fluid in the glass bulb
heat-responsive element, loading, painting unless painted by the sprinkler
manufacturer, shall be replaced.
Since sprinklers are inspected from the floor, it may be difficult to see the
bulb. If there is no color noted, a closer inspection can be done to make sure
there is liquid inside the bulb. Rough handling of glass bulb sprinklers
during shipment or installation can cause fractures in the bulb that allows the
fluid to leak out. This sprinkler will not operate unless the glass melts
(2700 deg. F).
The loss of bulb color will be addressed in the next edition (2017) of NFPA 25.
A public input as Second Revision No. 51 new text states, "Glass bulbs in
sprinklers exposed to sunlight or installed in cold environments such as
walk-in coolers and freezers might lose or change their temperature
classification color due to the environment. This loss of color should not be
confused with loss of fluid in the glass bulb. Tests have shown that this loss
or change of color in the bulb does not affect the operation or any other
performance characteristics of the sprinkler, and these sprinklers can be
allowed to remain in service. The tests also showed that when sprinklers
installed in cold environments were subjected to temperatures above 60°F
(15.5°C), the fluid color returned."
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Technical Update is prepared by the Technical Services Dept. of the AFSA: Vice
President of Engineering and Technical Services Roland Huggins, a PE registered
in fire protection engineering; Phill Brown, a NICET IV certified automatic
sprinkler technician and NFPA Certified Fire Protection Specialist (CFPS) and
Tom Wellen, a PE registered in fire protection engineering. This is provided
with the understanding that the AFSA assumes no liability for this opinion or
actions taken on it and they are not to be considered the official position of
the NFPA or its technical committees.
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