MARK X CLOSED CIRCUIT REBREATHER 

 TRAINING COURSE 



Robert J. Schmidt, Jr. 

 General Electric Company 



ABSTRACT 



During the TEKTITE II Man-In-The-Sea Program, 48 aquanaut 

 scientists were exposed to a seven day training course in the 

 use and maintenance of the Mark X Closed Circuit Rebreather, 

 This course included 30 hours of classroom instruction on the 

 use and maintenance of the Mark X and at least 10 hours of 

 in-water use of the unit, A sample training schedule and 

 written test are included in this report. 



EQUIPMENT 



The equipment used for this course was the General Electric Company's rebreath- 

 er Mark X, Mod 1 and Mod 3, the Mod 3 being the newer version of the Mark X. 

 The Mod 1 was used by the aquanauts on Missions 2-50, 3-50, and 4-50, and on 

 subsequent missions was used as a backup training unit. From mission 5-50 on, 

 the Mod 3 was the prime unit for the aquanaut habitat missions. 



The Mod 3 rebreather is a self-contained, back mounted, closed -circuit re- 

 breather featuring automatic and manual control of the oxygen partial 

 pressure. It weighs approximately 65 pounds, has a canister containing enough 

 baraljTme for a twelve hour dive, and a depth capability of 1500". The main 

 differences between the Mod 3 and the Mod 1 are easier and quicker maintenance 

 of the Mod 3, the Mod 3's breathing bag configuration versus the Mod I's 

 diaphragm unit^ the disposable scrubber cartridge of the Mod 3 versus the re- 

 packable scrubber in the Mod 1, and finally the lighter weight and better 

 packaging of the Mod 3. 



For the first few missions of TEKTITE II the rebreathers were limited to one 

 dive per baraljraie canister not to exceed four hours of use. Later, as the 

 program progressed and more experience and a higher level of confidence in 

 the Mark X was achieved, the time limit was changed to six hours use within an 

 eight hour period. This later time limit allowed more versatile use of the 

 Mark X and was still well within design and safety constraints. 



OBJECTIVE 



The main goal of the Mark X closed circuit rebreather training course was to 

 give the TEKTITE II aquanauts a thorough knowledge of the functioning and 

 maintenance of the Mark X. No diving or diving principles were taught during 

 the course so that the total time allowed could be devoted exclusively to the 

 use and maintenance of the Mark X. 



IV-7 



