Ignoramus6607 writes:

My tig torch and welder warn against
pressure over 50 PSI. How can I limit it for my carbonator pump.

I expect you'd need a bypass regulator, since the pump must need flow to
stay cool, so a static (?) regulator wouldn't suit.

Or how about this: you could get a whole McCann's carbonator unit (pump,
stainless pressure vessel, level switch) for about $200 or less on eBay,
and pressurize it with 50 psi air instead of CO2, and then you'd have a
stable 50 psi water out. And with a CO2 tank you could make soda after
work.