If you have to change one Pendant sprikler in an office, and the existing ones are standard response 165 deg links, can you replace that single sprinkler with a standard response 155 degree bulb, as long as size and k factor match?
Yes. 135º-175º are considered Ordinary Temperature sprinklers. The aesthetic of a colored frangible glass bulb in a forest of eutectic links may annoy an architect, but very few people outside the industry even notice sprinklers except in hotel rooms.
See NFPA 13, 2013 Edition, Table 188.8.131.52 Temperature Ratings, Classifications, and Color Codings & also 184.108.40.206
Just make sure that if the 165º sprinklers are standard response, the 155º sprinkler is as well. "220.127.116.11 When existing light hazard systems are converted to use quick-response or residential sprinklers, all sprinklers in a compartment shall be changed."
I can't point you to a black and white explicit answer, but NFPA categorizes sprinkler heads by temperature ranges, not exact temperatures, and both of those options are in the same range, so they should be acceptable. If you have a NFPA 13 2013 handbook the explanatory material for 6.2.5 suggests as much.
18.104.22.168 "Replacement sprinklers shall have the proper characteristics for the application intended, which include the following:
My interpretation is that the preference is to replace the sprinkler with the same type (note: "style" in the standard). So a link type sprinkler should be replaced with a link type sprinkler of the same orifice size, K-factor, temp rating, coating, deflector type, etc.. However, if an exact replacement sprinkler is not available, the sprinkler should be replaced with a type closest to the existing sprinkler with the same characteristics (orifice size, K-factor, temp rating, coating, deflector type, etc.) Usually the sprinkler manufacturers will provide a replacement sprinkler for ones no longer manufactured. This sprinkler should be the next choice in preference.
If you replace a link type sprinkler with a glass bulb type of the same characteristics, it probably will work, but keep in mind when you do that some AHJ's may require documentation that this replacement sprinkler is the closest available in characteristics to the existing sprinklers.
I totally get that in the real world, the building owners don't always keep their replacement sprinklers handy as they are required to do, and that service trucks don't always keep every style and type of replacement sprinkler, so sometimes you need to replace a sprinkler with one close to the existing, but not an exact replacement, especially in an emergency service call.
My opinion is that this is written this way to give some assurance that when a sprinkler is replaced, it is replaced with a correct sprinkler having the right characteristics and will perform as designed and intended. It is very easy to replace the sprinkler with one having the same thread size without verifying the sprinkler will operate and perform as designed and intended by checking orifice size, K-factor, temp rating, coating, deflector type, design requirements, etc.
Hope this helps, one Instructor's opinion,
Retrieving data ...