Hello,
I have noticed the lack of Sprinkler system equipment type in the semantaic model while I can see LawnMower equipment type.
But lawn requires cutting and irrigation… 
The Valve Equipment type is rather a part of irrigation system.
Are there any plans to extend the semantic model in future relases based on feedback from the community?
See Discussion on ontology improvement · Issue #1791 · openhab/openhab-core · GitHub
I’m not sure there is a good answer for expanding the semantic model at this time. Some areas are over specified (do we really need five different types of door equipment?) and others are lacking.
Ultimately, unless you are using HABot, the specific Equipment tag you use doesn’t really matter a whole lot. What some people do to get an Equipment tag that makes sense is to use some tag that isn’t being used and is unlikely to be used and then changing the settings on the Overview page to change the name of the card to what you really want.
If you are using HABot, you can get part of the way there by using synonyms.
Ultimately, as I expressed on that issue, I think that we need to reconsider the semantic tags. Trying to list everything possible location and equipment in a separate tag is going to lead to hundreds of tags, all of which require special handling in the code, translation to other languages, etc. It’s not supportable.
I would probably just use the Valve tag for the sprinkler system. That’s the closest.