Q1: You have a customer that assembles and ships Passenger Service Units (PSU) containing oxygen generators but does not place the EX numbers on the PSU package. You ask if the outside package must be marked with the EX approval number associated with the individual oxygen generator contained within.

A1: The answer is no. As specified in § 173.168, there is no requirement to place the EX number on an outside package containing a chemical oxygen generator. However, under § 173.168(d), the outside surface of equipment containing a chemical oxygen generator that is not readily apparent (e.g., a sealed passenger service unit) must be clearly marked to indicate the presence of the oxygen generator (example: "Oxygen Generator Inside").

Q2: The company referenced above has an affiliated company that manufactures chemical oxygen generators and has several EX numbers. Each time the affiliated company creates a new stock number it applies for a new EX number although the same explosives/primer is used in all other generators. You ask when is a new EX number required for chemical oxygen generators?

A2: As provided in § 173.56(a)(2), a previously approved explosive (or new oxygen generator) with a design change is considered a new explosive and must be examined and approved by the Associate Administrator under the provisions of Part 107 Subpart H. However, if the chemical oxygen generator retains the exact same design and drawing number as approved under the EX approval, a change in a part number would only require a modification under § 107.709.

Q3: You ask if, prior to the final rule entitled "Chemical Oxygen Generators" under Docket No. PHMSA-2009-0238 (HM-224G) published on October 15, 2009 [74 FR 5289], PSU manufactures were required to display the Competent Authority (CA) number on a shipment of a PSU which was not in compliance with EX number requirements.

A3: The answer is yes. Prior to the publication of HM-224G, the CA number was required to be marked on the outside packaging per Special Provision 60 of § 172.102, Special Provisions.

Q4: You ask if the PSU manufacturer is required to put an EX number on the outer package of the oxygen generator since it does not make the oxygen generator. You state that the outer package meets all of the marking requirements in § 173.168.

A4: See A1.

Q5: You ask in the event a PSU containing a chemical oxygen generator needs to be returned to the manufacturer, may you use the EX number provided to the generator maker?

A5: The answer is yes. The manufacturer's EX number may be utilized on the PSU containing a chemical oxygen generator for shipments returned to the manufacturer.