Prv's on cornelius kegs

[bluc]

Wondering how to calculate spring strength needed for x pressure on a prv.

I age in corney kegs and was content knowing they have a prv. A mate mentioned it may not be ideal. After some research i see they have max 100psi.
Looking at this purely in worse case scenario of a fire these things would be bombs.
I would like to set psi to maybe .25psi or .5psi max.

How do i work out spring strength needed or should i remove spring and just let it vent the mechanism as needed.
I want to keep bugs out and not create bombs all at same time.