229 Neb. Admin. Code, ch. 27, § 006
Each pressure vessel shall be provided with pressure relief devices, indicating and controlling devices as necessary to protect against overpressure. The devices shall be so constructed, located and installed that they cannot readily be rendered inoperative. The relieving capacity of such pressure relief device shall be adequate to prevent a rise in pressure in the vessel of more than 10% or 3 psig, whichever is greater, above the maximum allowable working pressure except when multiple relieving devices are provided, they shall prevent the pressure from rising more than 16% or 4 psig, whichever is greater, above the maximum allowable working pressure. When multiple pressure relieving devices are provided, at least one device shall be set at or below the maximum allowable working pressure and the additional devices shall be set no higher than 105% of the maximum allowable working pressure. When an additional hazard is involved due to fire or other unexpected sources of external heat, the pressure relief devices shall meet the requirements of ASME code.
229 Neb. Admin. Code, ch. 27, § 006