Cal. Code Regs. tit. 8, § 5501
(c) Where oxygen is stored as a liquid, noncombustible surfacing shall be provided in an area extending at least 3 feet from points at ground level upon which any leakage of liquid oxygen might fall during operation of the system and filling of a storage container. Such an area under liquid delivery connections of mobile supply equipment shall be at least the full width of the vehicle and at least 8 feet in the transverse direction. For purposes of this Article, asphaltic or bitumastic paving is considered to be combustible. The slope, if any, of such areas shall consider possible flow of spilled liquid oxygen to adjacent combustible material.
Note: When locating bulk oxygen systems near aboveground flammable or combustible liquid storage which may be either indoors or outdoors, it is advisable to locate the system on ground higher than the flammable or combustible liquid storage.
1. Amendment filed 7-16-76; effective thirtieth day thereafter (Register 76, No. 29).