Pressure is one of the variables - other is maximum flow, in case of pressure relief valve (safety valve) if valve was calculated at 50psi and flow of say 10gallon/sec, if you change the diameter, your flow will drop significantly, in case of 1" drop to 3/4" drop will be by nearly 45%! and that is significant drop...
i would suggest do not use reducer but 1" relief valve as required...
if you wan to establish bit more calculations on the subject, go to this site and have play with variations, sele3ct correct calculator and enjoy : http://www.tlv.com/global/TI/calculator/
reverse engineering will be here: https://www.physicsforums.com/threads/calculate-water-pressure-coming-out-of-a-pipe.274737/
hope this will help you a bit - do not forget to vote...
Answers & Comments
Pressure is one of the variables - other is maximum flow, in case of pressure relief valve (safety valve) if valve was calculated at 50psi and flow of say 10gallon/sec, if you change the diameter, your flow will drop significantly, in case of 1" drop to 3/4" drop will be by nearly 45%! and that is significant drop...
i would suggest do not use reducer but 1" relief valve as required...
if you wan to establish bit more calculations on the subject, go to this site and have play with variations, sele3ct correct calculator and enjoy :
http://www.tlv.com/global/TI/calculator/
reverse engineering will be here:
https://www.physicsforums.com/threads/calculate-water-pressure-coming-out-of-a-pipe.274737/
hope this will help you a bit - do not forget to vote...