ECS Equipment - Water Management Section

ECS Equipment - Water Management Section

DESCENT STAGE WATER TANK

The descent stage water tank is an aluminum tank with an internally mounted standpipe and bladder. The bladder contains the water; the space between the bladder is charged with nitrogen according to a schedule dependent on the load (48.2 psia maximum at +800 F). The nitrogen squeezes the water out of the bladder through the standpipe and into the system. The tank outlet is connected to the water control module. Water from the descent water tank is routed through the water tank select valve by setting it to the descent position.

Descent Water Valve The descent water (DES H20) valve (see Water Control Module, below) is a manually operated, poppet-type shutoff valve. The valve has open and closed positions. In the open position, the valve provides high-pressure water flow from the descent tank to the water dispenser.

ASCENT STAGE WATER TANKS

The ascent stage water tanks are in the overhead unpressurized portion of the cabin. They are similar to the descent stage water tank, but are smaller. An initial nitrogen charge of 48.2 psia at +80' F is used in each tank. The tank outlets are connected to the water control module. Water from the ascent water tanks is routed through the water tank selector valve by setting it to the ascent position.

Ascent Water Valve The ascent water valve, at the top of the water control module (see Water Control Module, below), is a manually operated, poppet-type shutoff valve. The valve has open and closed positions. In the open position, the valve provides high-pressure water flow from the ascent tank to the water dispenser.

WATER QUANTITY MEASURING DEVICE

A water quantity measuring device (WQMD) for each of the three water tanks measures the quantity of water in the tank. The analog voltage output of the WQMD is fed to the quantity indicator and is displayed on the H20 scale as the percentage of water remaining in the tanks.

The WQMD measures the quantity of water by sensing the pressure/temperature ratio of the tank pressurizing gas. This ratio decreases as the gas expands in expelling the water. An analog computer subtracts a voltage inversely proportional to the pressure/temperature ratio from a set constant voltage, which represents the total volume of the tank. The result, tank volume minus gas volume, is water volume.

WATER CONTROL MODULE

The manual controls of the WIVIS are grouped together on the water control module. The module consists of check valves, shutoff valves, a water tank selector valve, and water pressure regulators. Each water tank outlet is connected to the module, which diverts the water to selected flow paths.

Water Management Controls

Check Valves There are five check valves in the water control module: one in each tank feed line, and one in each discharge line from the ARS water separators. The check valves prevent water flow from the module to the water tanks and water separators.

Water Tank Selector Valve The water tank selector valve is a manually operated, three-position, two-spool valve (see Water Control Module, above). The two spools (primary and secondary), linked to the valve handle, rearrange the internal ports to establish proper flow paths. The valve has descent, ascent, and secondary positions. In the descent position, the primary spool establishes a flow path between the descent water tank and the primary water manifold. In the ascent position, the primary spool establishes a flow path between the ascent tanks and the primary water manifold. When the valve is in the secondary position, flow is diverted from the ARS separator to the secondary manifold and water is routed from the ascent water tanks to the secondary manifold.

Water Tank Selector Valve

Water Pressure Regulators Three water pressure regulators are in the WMS. Two are in series in the primary manifold and in the secondary manifold, and one is located external to the water module in the water pressure regulator module. The regulators contain a spring-loaded diaphragm that senses the differential between ARS reference pressure and the downstream water pressure. The diaphragm moves a balanced lever attached to a metering poppet. The water discharge pressure is maintained at 0.5 to 1.0 psi above the reference pressure.

Primary Evaporator Flow Valve No. 1 The primary evaporator flow No. 1 valve is a manually operated, poppet-type shutoff valve (see Water Control Module, above). It has open and closed positions. In the open position, the valve allows flow from the ascent or descent water tanks, through the primary regulators, to the primary sublimator.

Primary Evaporator Flow Valve No. 2 The primary evaporator flow No. 2 valve is a manually operated, poppet-type shutoff valve (see Water Control Module, above). It has open and closed positions. In the open position, the valve acts as a backup to the primary evaporator flow valve to provide ascent tank water from the secondary water manifold to the primary sublimator.

Secondary Evaporator Flow Valve The secondary evaporator flow valve is a manually operated, poppet-type shutoff valve. It has open and close positions. The valve controls water flow from the secondary water manifold to the secondary sublimator and to the suit circuit sublimator.

Water Pressure Regulator Module The water pressure regulator module consists of a pressure regulator and a manifold. The module is located in the secondary water circuit, downstream and in series with the secondary water pressure regulator in the water control module.

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