14 CFR §25.1450

1. (a)For the purpose of this section, a chemical oxygen generator is defined as a device which produces oxygen by chemical reaction.
2. (b)Each chemical oxygen generator must be designed and installed in accordance with the following requirements:
   1. (1)Surface temperature developed by the generator during operation may not create a hazard to the airplane or to its occupants.
   2. (2)Means must be provided to relieve any internal pressure that may be hazardous.
   3. (3)Except as provided in SFAR 109, each chemical oxygen generator installation must meet the requirements of § 25.795(d).
3. (c)In addition to meeting the requirements in paragraph (b) of this section, each portable chemical oxygen generator that is capable of sustained operation by successive replacement of a generator element must be placarded to show—
   1. (1)The rate of oxygen flow, in liters per minute;
   2. (2)The duration of oxygen flow, in minutes, for the replaceable generator element; and
   3. (3)A warning that the replaceable generator element may be hot, unless the element construction is such that the surface temperature cannot exceed 100 degrees F.