Section 6.
FOOD SUPPLY
1.
FOOD SUPPLY. Food is always prepared outside the PV to prevent
hydrocarbon buildup. Food is passed into the PV through a service lock. A
food cooler, when required in the PV, will use only ice cubes as the cooling
medium.
Section 7.
POTABLE WATER AND SANITARY SYSTEM
1.
POTABLE WATER AND SANITARY SYSTEM. Potable water and sanitary systems
are generally classified as water lines and drain lines. Water lines are
required to provide hot and cold potable water for the shower, sink, and
toilet.
A schematic diagram of a typical chamber potable water and sanitary system is
shown in Figure 6-27. Cold water is supplied to the chamber from an external
water reservoir which is pressurized at 50 psi over the chamber pressure
using helium as the driving gas. Hot water is provided to the chamber from
the water in the potable water reservoir routed through a high pressure heat
exchanger. The heat exchanger should be sized to operate utilizing boiler
water at 190 to 200 deg. F water, to provide a comfortable 160 deg. F tap
water to the occupants. The drain system should be designed as a gravity
flow to a sanitary holding tank. The valving should be interloaded so that
when the sanitary holding tank is full and requires emptying, the tank is
isolated from the chamber to prevent accidental injury to the occupants. An
equalizing line is provided from the sanitary tank back to the chamber with a
filter inside the chamber to eliminate odors. Pressure relief valves set at
60 psi must be installed in both the hot and cold water lines to relieve the
pressure in the lines when the chamber pressure is reduced. The electrical
interlocking shown on Figure 6-28 provides the safety systems for the
sanitary tank.
To empty the sanitary tank, the chamber drain and filter seal valve (A) first
must be closed, second the vent valve (B) must be opened, then the drain
valve (C) can be opened to empty the reservoir. A valve (D) is provided to
add fresh water to flush out the sanitary tank. As noted, a removable flex
line (garden hose) is required by the health codes to prevent any cross
connection between the sanitary system and the potable water system.
The potable water and sanitary system should have the following features:
a.
Hull Valves. The external hull valve should be of the
one-quarter turn quick-acting type.
b.
Tank Sizes. Potable water supply tanks and waste water tanks
should be of same size to prevent overflow, and backup of waste water or
sewage into vents.
c.
Vents. All tanks should have vents for adequate drainage.
Each
vent should be equipped with fume and odor filters.
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