Unisim Blowdown Utility, Emergency depressurizing
Compliance with API -521 std "EDP (Emergency Depressuring) is generally initiated by manual push button. In case of fire, the operator will push the EDP push button in the control room. That will initiate SDV valves closing and BDV valves opening. The hydrocarbon fluid will be released to flare so that the pressure of the system will be depressurized to lower pressure at certain time (recommendation from API STD 521, decrease the pressure to 100 psig or 50 % of the system design pressure within 15 minutes)