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Actuator
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Electrical connector
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Position indicator
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Manual override knob.
The diameter of the valve body is nine inches (23 cm).
Location
The valves are in the floor area of the forward cargo compartment, forward of the ball panels, below the left powered drive units.
The vent valve is the forward most valve and the forward cargo heat valve is the aft valve.
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A/C -EQUIPMENT COOLING -VENT VALVE AND FORWARD CARGO HEAT VALVE
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A/C -EQUIPMENT COOLING -DUCTING
General
The equipment cooling system has these ducts:
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Supply ducts
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Smoke clearance duct
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Exhaust ducts
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Vent duct.
The supply ducts give cabin air to equipment and areas that need blow-through cooling.
The smoke clearance duct moves smoke from the supply part of the system or vents the system for differential cooling when necessary.
The exhaust ducts move air from equipment and areas that need pull-through cooling.
The vent duct moves air from the exhaust duct to the area next to the forward pressurization outflow valve.
Physical Description
There are different types of equipment cooling ducts. Some are flexible and some are rigid. The ducts can have different shapes; round, oval, and rectangle.
Location
The supply ducts are in these locations:
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Forward cargo compartment, left sidewall area
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Forward cargo compartment, under the floor area
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Forward cargo compartment, right sidewall area
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Main equipment center (MEC)
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Forward equipment center (FEC)
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Flight deck (not shown).
The smoke clearance duct is in the left sidewall area of the forward cargo compartment.
The exhaust ducts are in these locations:
*
Flight deck (not shown)
*
Forward equipment center (FEC)
*
Main equipment center (MEC)
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Forward cargo compartment, right sidewall area
*
Forward cargo compartment, under the floor area.
The vent duct is under the floor of the forward cargo compartment and the MEC.
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A/C -EQUIPMENT COOLING -DUCTING
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A/C -EQUIPMENT COOLING -CONTROLLER
Purpose
The equipment cooling controllers (ECC) supply control of the supply fans and the override valve.
Location
Both controllers are in the main equipment center (MEC). The left controller is below the P310 standby power management panel. The right controller is below the P300 auxiliary power panel.
Physical Description
The controllers are identical, solid state units. Each ECC has two independent channels, one for supply fan control and one for override valve control. The controllers have two electrical connectors.
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A/C -EQUIPMENT COOLING -CONTROLLER
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A/C -EQUIPMENT COOLING -FUNCTIONAL DESCRIPTION -LOW FLOW SENSORS
General
The sensors calculate when the flow of air is below the amount necessary to cool the electrical and electronic equipment.
The flight deck (F/D) low flow sensor sends low flow information to the right ECC and to the right ECSMC. The sensor sends air temperature information to the right ECSMC.
The main equipment center (MEC) low flow sensor sends low flow information to the left ECC and to the left ECSMC. The sensor air temperature information to the left ECSMC.
Power
The sensors get power from the P210 right power management panel and the P310 standby power management panel.
ECC
The ECCs use low flow information in their takeover control logic. See the section on the controller for more information how the ECCs use low flow information.
The ECCs share low flow information through a cross talk connection.
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