131.835—Portable fire extinguishers.
(a)
Except as provided by paragraph (b) of this section, ach portable fire extinguisher must be marked with a number, and the site of its stowage must be marked with a corresponding number at least 13 millimeters ( 1/2 -inch) high.
(b)
If only one type and size of portable fire extinguisher is carried, the number may be omitted.