154 OPERATIONAL AND EMERGENCY BILES 



Next, these two aquanauts will enter the PTC (hatch open at all times), and check together 

 both the routine mode of gas delivery, via the regulator (outboard) controlled pipeline, and 

 next the emergency (inboard) direct-flow system, assuring that all valves operate satisfactorily 

 without stick or leak. During this procedure, caution must be exercised to flow only a small 

 amount of the gas in each manifold, in order to preserve normal gas balance in the PTC. Once 

 satisfactory flow has been demonstrated in both channels on each gas system, and the Oj Flow- 

 Rator Tested to 20 cfm for a period not to exceed ten seconds , all internal valves will be 

 secured. The PTC is now ready for occupation. 



After all occupants are on board, check O2 level before securing entrance hatch. Prior to 

 descent from surface, this should not exceed 25 percent if leaving from the deck, at sea-level 

 pressure. If departing from Sealab n depth, O2 level may not exceed 10 percent . In any case, 

 overoxygenation can be corrected by inflow of helium, at a slow rate, and with the entrance 

 hatch open . Once these requirements are met, the entrance hatch will be shut, and the transfer 

 in either vertical direction can be accomplished. 



During transit in either ascent or descent, both O2 and CO2 levels will be checked every 

 three minutes . Oxygen levels will not be allowed to exceed 1.5 atmospheres (Strasberg), and 

 CO 2 levels must not exceed 0.5 percent (Dwyer). Should these values be exceeded, notify top- 

 side, and appropriate orders or measures will be taken. In event of a stay in excess of 3 to 5 

 minutes in the PTC, CO2 scrubber operations and O2 bleeding will become mandatory. Since 

 CO2 buildup will be a controlling factor, the scrubber should be in operation prior to entrance- 

 hatch closure. Oxygen should be bled in, after five minutes, at a rate to maintain a constant 

 partial pressure of O2 of not less than 160 mm Hg = 0.2 atmosphere, and not more than 1.0 

 atmosphere. In the event of Krasberg unit failure, a safe rule of thumb will be the admission 

 of 10 cu ft of O2 every 30 minutes. In event of power failure, the foot-operated CO2 scrubber 

 should be operated continuously. Should this latter equipment fail, spread the absorbent in the 

 lower flats of the PTC, and expend as little energy as possible. 



Abnormal Use of PTC 



It is conceivable that through loss of mating capability, or necessity of use as a deck de- 

 compression facility, the PTC might require external control and monitoring of internal en- 

 vironment. Provisions have been made for this unlikely situation. Three access penetrations 

 are provided in the design of the PTC to permit complete atmospheric control by topside per- 

 sonnel. One of these penetrations will be available for gas sampling, while the remaining 

 apertures will be available for decompression exhaust and oxygen replenishment. An external 

 CO2 scrubber will be available for use. Thus, even without active participation of the aquanauts, 

 decompression can be accomplished within the PTC mounted topside, and without use of the 

 Deck Decompression Chamber (DDC). The necessary steps to establish this capability are as 

 follows. 



1. In event of delay in the mating of PTC to DDC in excess of ten minutes after return to 

 the staging vessel, caps will be removed from inlet and exhaust penetration lines to the PTC, 

 and appropriate topside connections made. The inlet line will provide only compressed air . 

 The outlet line will exhaust for decompression. No attempt will be made to provide an He/Oj 

 mix. Decompression calculations will simply be changed to allow for the different gas mix. 



2. Varying percentages of oxygen will be supplied to the PTC, as dictated by the physical 

 condition of the occupants, and the decompression profile. These determinations will be the 

 sole responsibility of the Principal Investigator. 



3. Hookup of the CO 2 scrubber system (external) will be dictated by operational circum- 

 stances. Should a delay of more than one hour be anticipated, action will be instituted to 

 assure incorporation of this life support item. 



4. Communication with, the occupants of the PTC will be maintained throughout, and 

 recorded. 



