Examples of sprinkler head defects
Sprinkler heads can be damaged and distorted, this will affect the heads ability to function. This is a common occurrence and as can be seen from these images often routine maintenance does not pick up these issues. The heads in these shots have clearly been left and been subject to further environmental deterioration.
Many environments are harsh, and sprinklers could be sprayed with paint or chemicals. Water can be hard or soft and left stagnant can corrode pipes, often leaving debris and build up inside.
Some sprinkler head types incorporating o-rings seals, may need testing earlier and possibly with greater regularity than other types, to ensure the system functions as intended when required.
Test for the things you can't see
Routine maintenance including a visual inspection is essential but over time there are many other issues that can arise that only extensive inspection and testing can identify, for example: