As i promised, a picture of my injector tester.
I have a fine filter inside the bottle to clean the fluid.
Its best using a jack with removable piston, so you can access from the inside to fasten the 90dgr. nipple for the bottle.
weld the piston to the top nut.
Drill a hole in the piston, and make tread for the coupling to the T piece.
The manometer i a fluid filled type, so the needle dont move to fast.
0-250 bar.