Double acting valve actuator and available codes

[tchaiket]

Hi--

I'm studying for the Control System Engineering License Exam. Can someone offer a rule of thumb of double acting valve actuator regarding fail safe options?
Also, do you know some websites that offer free download of some ISA, NFPA, and ASTM codes ?

Thanks!

t

 

[busbar]

I can't address your specific requirements, but think for a moment on "free download." For places like ISA, NFPA and ASTM, standards documents are their primary source of income. Do you think it is realistic that they be found available for "free"?