Maybe this will answer some of your questions. First, there is only one manufacturer that I can find for the glass bulbs. It does not make a difference as to the orientation of the head. There are only two sizes of glass bulbs. The differences are in the dimeter. One is 5 mm and the other 3 mm. It is my understanding they use the 3 mm in the quick response heads.

My question was posed to the National Fire Sprinkler Association. They had no information as to scratches on the glass bulbs making a difference in the activation temperature. What they did say is that the bulb is activated when the liquid inside the glass bulb expands causing an outward force on the glass. There is scientific studied that indicate the section of the glass bulb the will be the first to fail is the location at each end where the glass bubbles out.

I have contacted Viking and TYCO. Could not get any information from TYCO. Viking guided me to a study done by a private engineer company. The only testing this company did was on the amount of force that would be needed to be applied by the water pressure in the sprinkler pipe to crush the glass bulb. This is not the same condition I was acquiring about.

What a was investigating was premature activations. There was information supplied that the exposure of the glass bulb to temperatures higher than the ambient exposure temperature recommended could possibly have an effect as to what temperature would activate the glass bulb. NFPA 13 I believe has a list of the maximum ambient temperatures for different temperature values sprinkler heads. As an example a 135 degree F rated head should not be exposed to any ambient temperature more than 100 degree F. The problem with this assumption is that I can find no testing data to support that hypothesis.

Jim Mazerat
Forensic Investigations Group