Video of HVAC 089 fixed orifice piston closer look inside in HVAC course by Love2HVAC with Ty Branaman channel, video No. 111 free certified online
If you just got here I recommend going back to at least HVAC 052 HVAC 052 Measuring Wet Bulb, Dry Bulb and Humidity here https://www.youtube.com/watch?vcW5XA1fKaAU and continue to HVAC 059 Example with fixed orifice.
Target superheat chart I made from the formula for the formula and chart
https://www.love2hvac.com/supporting-documents
Craig and Bryan both are great resources. here are some links below to help.
Craig with @acservicetechchannel does a great job explaining why the TXV is superior to the fixed orifice
https://www.youtube.com/watch?vHcGz5ihdJkc
Target superheat from Craig
https://www.acservicetech.com/target-superheat
https://www.youtube.com/watch?vbIL9BrKCujc
Bryan Orr discusses target superheat @HVACS
https://www.youtube.com/watch?vK0WeVON0B5o
HVACR school target superheat
https://hvacrschool.com/what-should-my-superheat-be/
My favorite HVAC App, we will be doing a video on this soon
https://measurequick.com/
articles on target superheat.
https://www.achrnews.com/articles/92392-proper-use-of-superheat-measurements
https://www.contractingbusiness.com/service/article/20861835/service-clinic-taking-the-mystery-out-of-superheat