(a) Rating. A numerical-alphabetical designation of a portable fire extinguisher which indicates the extinguishing potential (the number) and the class of fire (the letter) for which the extinguisher is suitable.

(b) Recognized Testing Laboratory. For the purpose of this article, a recognized testing laboratory shall mean any agency staffed by qualified personnel and properly equipped to conduct the particular test in question, and who are regularly engaged in conducting tests. Laboratories other than those specified in Section 13162(b) of the Health and Safety Code, shall be approved by the State Fire Marshal.

(c) Rechargeable (Refillable) Fire Extinguisher. A rechargeable (refillable) fire extinguisher is capable of undergoing complete maintenance, including internal inspection of the pressure vessel, replacement of all sub-standard parts and seals, and hydrostatic testing. The fire extinguisher is capable of being recharged with agent and restored to its full operating capability by the standard practices used by licensed concerns. Rechargeable (refillable) fire extinguishers shall be marked “Recharge Immediately After Any Use” or with a similar equivalent marking.

(d) Recharging. The replacement of the extinguishing agent, also including the expellant for certain types of extinguishers.