Chapter 47 

 AAARK-VI MIXED-GAS BREATHING APPARATUS 



J. C. Bladh and P. A. Wells 



U. S. Navy Mine Defense Laboratory 



Panama City, Florida 



INTRODUCTION 



The initial preparation of gear and the training of Sealab personnel in the use of the Mk-VI 

 Scuba was accomplished under the supervision of the Mine Defense Laboratory Diving Officer. 

 Experience gained from Sealab I dictated that the following preparations and procurement of 

 material must first be accomplished to support the training as well as the Sealab II effort it- 

 self: 



1. Procure 20 Mk-VI rigs 



2. Build a Mk-VI locker and gas rack 



3. Procure portable recompression chamber 



4. Procure mixed gas (He0 2 and NO 2) and CO2 absorbent (Baralyme) 



5. Establish a training schedule and lesson plane 



6. Schedule boats as required 



7. Enlarge present diving locker and shower room to accommodate Sealab personnel 



8. Procure transfer pump (PPI) for charging rigs 



9. Procure adequate gas analyzers 



10. Establish and procure a Mk-VI spare-parts inventory. 



PREPARATION 



On Feb. 1, work commenced at the Mine Defense Laboratory, fabricating a Mk-VI locker 

 and work area. This included the construction of a gas rack, drying rack, vest stowage, suit- 

 able work benches and lockers, as well as a new locker and shower room. This work was 

 completed by Apr. 1. This locker was used as a guide for the construction of the Mk-VI locker 

 aboard the support vessel. 



On Mar. 28, 20 Mk-VI units arrived at the Mine Defense Laboratory from the Naval Oper- 

 ations Support Group Pacific and immediately were given a visual inspection, cylinder test, dip 

 test and operational test. In addition to the above, and as an added safety factor, three Hansen 

 fittings from each unit were modified to provide a positive lock to the hose fittings. Two of 

 these modified Hansen fittings are located at the control block and one at the canister. 



During March, the following gas and equipment were procured to support the training pro- 

 gram. 



1. 10,400 cu ft He 



6,160 cu ft 60/40 N2O2 

 2,640 cu ft 40/60 N2O2 

 3,960 cu ft 32.5/67.5 N2O2 

 2,200 cu ft N2 

 4,400 cu ft O2 



2. A two-lock portable Dixie recompression chamber was obtained from Explosive Ord- 

 nance Disposal Unit TWO, Charleston. In addition to the above, utility boats, YSD's and MSO's 

 were programmed and scheduled to support the training program. 



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