Where?
Temperature rating?
What is the occupancy?
Hazard Classification?
Wet, dry, or pre-action?
Is it a pipe-schedule system?
Orifice diameter?
Ceiling sprinkler rating? (Appears to be a 165F 1/2 orifice sprinkler) but you didn't say
Why does it need to be replaced? It's tarnished from the photos but it looks functional.
It's a standard response sprinkler based on the link design.
The link is thicker than my toe nails (I eat lots of cheese, which makes calcium, which makes toenails).
PS: What will you do if you know the RTI? Model it? That fact you want a response time without using the proper term tells me you are branching into engineering.
PPS: What is Q prime of the design fire?
I am very apprehensive about this post. This sounds like some health care sprinkler post from New Mexico posted last week on another web site. I call this forum shopping.