Please help me - PVR clunking noise is driving me crazy

[helpneeded]

I’m being driven crazy by a pressure release value clunking on and off repeatedly for hours on end. I have discovered the pvr, which has been recently replaced, is a 3 bar (the one before was 6bar). I can also see I have an in line pressure tank (also new, but before the new PVR fitted) in the flow that seems to be set at 50psi / 3bar. Some photos attached. Is the pressure in the pressure tank set too high? I am tempted to reduce the pressure in the pressure tank to see if that helps (not sure how to do that though).There is a closed valve also in the flow, which if I close stops all noise, but then have no water.

 

[helpneeded]

Story inline pressure tank is set at 50psi / 3.5 bar