Spring Design - Need help with it.

Hello all,

I am under the process of designing the Pressure safety valve ,the core component of PRV is spring.just i want to know about the spring design .For eg my max allowable pressure is 5 bar, then i want to set the spring to stay uncompressed at 5 bar and the spring has to compress after 5 bar for this condition how to decide the coil diameter ,spring dia ,no.of turns ,height of the spring.MOC for spring is Stainless steel.Is there any formula to find this values or any standard to refer ......pls any one help in this case to design a spring and the spring seating area may be flexible it may vary accordingly but the set pressure is fixed...

Regards
Dinesh