Metabolic Oxygen System-oxygen storage/generation, distribution, &metering.
1.0 ft3/hr per man. Partial pressure between 18.4 and 23.6%. Above 25% becomes excessive fire hazard. We have calculated the oxygen necessary for a 12 hour mission plus a 26 hour time period in case the hull must be inhabited for a longer in an emergency situation.

2 crew * 1.0 ft3/hr/man * (12 hours + 26 hours) = 76 ft3 O2 per mission

The oxygen will be stored at 3,000 PSI and will be breathed at approximately 150 PSI. This means that the oxygen tanks will be approximately 4 ft3 in volume. The oxygen tanks must be securely anchored in place and must be able to be locked in the open position (so it doesn't close while filling.) They will have a shut-off valve upstream of the supply pressure gauge. The gauge will be able to moniter when the shut-off valve is open.

Since our oxygen is being compressed and stored at over 1,000 PSI, we will be using a nickel-copper alloy (monel) for the piping, fittings, and valves.

Control of the release of oxygen will be automatic but we must be sure:

(a) there is no electrical fire hazard,
(b) there is a warning if the system fails,
(c) it can be manually operated if there are problems,
(d) it is free from errors caused by temperature, humidity, or total pressure.
(e) it can be removed for testing (once every year to 18 months max.)
Our oxygen tanks will be located in the closed-off back portion of the vehicle. Manual controlling will be capable from within the pressure hull through connections.

Carbon Dioxide & Odor Removal System
Cabin air is drawn through this system and treated to remove CO2 and odors.

Over a long period of time, there should no be more than 1% of partial pressure due to CO2. The removal system will have at least a 20% safety factor of instantaneous removal. We will be using a CO2 scrubber system using LiOH. The system must be non-corrosive, non-toxic, and cannot contain uncoated aluminum. The canisters will be easy to replace and must have backup. Using LiOH means contact with eyes or skin must be prevented. We will have two scrubbers within the pressure hull, one will be located towards the rear of the hull and the other will be located right behind the crew seats to prevent the possibility of having it leak onto the crew.

A fresh canister and dust filter will be installed before each mission. We will also have a CO2 indicator.

Temperature and Humidity Control System
Heat and water vapor that will be released by the crew and equipment must be controlled. Although the deep ocean provides a stable thermal environment, temperature control is still necessary.

Emergency Breathing Systems
Emergency oxygen will be supplied by masks with chemical oxygen. We will need at least 2 hours of emergency supply per crew. Our emergency oxygen supply should allow enough time for vehicle to surface plus 50% margin. We will be using full-face masks that contain voice disks for communication with the habitat as well as with the other crew member. CO2 will be removed from the mask. These masks will be located above the seats and will be released in the even of an emergency.

Food and Beverage System
Considering the intended short duration of our missions this will not be a big problem. Food such as sandwiches, canned foods, or hot and cold food and beverages can be stored in thermos containers. Extra food should be provided in the case of an emergency. Water, whether for washing or drinking, should meet purity standards so that it is drinkable in case of an emergency.

Waste Management System
Since our missions will only be about 12 hours, we should only need something to collect the waste. Wastes we will have to be concerned with are mainly urine, waste food, any possible trash, and, possibly, feces collection. This will be taken care of with a simple hole-style toilet located on one of the curved side of the hull. Feces collections should not be necessary except possibly in the event of an emergency. A waste basket will be provided for any trash.

Fire Managament System
Everything should be between self-extinguishing in 18-28% O2. The fire extinguishers will have to be suitable for use in a closed environment. We will have ABC type fire extinguishers located on the back of the crew seats. (For more information see the medical section of the station.)

Life Support Instrumentation
Instruments we will have to make sure the cabin's atmosphere is suitable for the crew should give the following data:

(1) Oxygen content of the cabin atmosphere. This should have different power supplies to ensure that it does not fail or give incorrect data.
(2) CO2 content of the cabin atmosphere.
(3) Pressure.
(4) Relative humidity. This will be a dial-type indicator.
(5) Temperature. This can be an electric temperature-sensing device. We will have a bi-metallic element temperature indicator as well.
(6) Contaminants. This may not be necessary considering our missions are only 14 hours in duration.

Emergency Equipment
Emergency equipment should include:

(1) Life jackets of the inflatable type in case evacuation is necessary.
(2) Portable hand-held signal lights(s).
(3) Emergency lighting independent of the normal lighting with a different source.
(4) A system for the recovery of the vehicle at its heaviest condition.
(5) Emergency de-ballasting systems.
(6) Emergency oxygen supply (see above).
(See the medical section of the station for more information.)