What is the purpose of outflow valve?

Outflow valve: Allows for air to exit the cabin at a controlled rate which results in the cabin becoming pressurized. Safety/Dump Valve: If the outflow valve fails, the dump valve will release excess pressure (can be manually activated) by a squat switch to prevent pressurization on the ground.

Why does a plane need an outflow valve?

To keep the aircraft cabin pressure at a safe level, any incoming air is held within the cabin through the use of an automatic outflow valve. This valve opens and closes on a regular basis to release the incoming air at the rate regulated by pressure sensors.

How does an aircraft outflow valve work?

Most airplanes control their cabin pressure via an outflow valve. If an airplane’s cabin exceeds the pressure for which it’s specified, the outflow valve will open. In the open position, excess air will bleed out. The cabin pressure will then drop to an appropriate level, resulting in the outflow valve closing.

What is the primary function of the cabin pressurization system outflow valve?

All exhaust air is dumped to atmosphere via an outflow valve, usually at the rear of the fuselage. This valve controls the cabin pressure and also acts as a safety relief valve, in addition to other safety relief valves.

What is cabin altitude?

The pressure altitude corresponding to pressure inside the cabin or, in the case of combat aircraft, the cockpit. Above a certain altitude, the crew tries to maintain a constant cabin altitude.

What altitude is a plane pressurized to?

8,000 feet
Most aircraft cabins are pressurized to 8,000 feet above sea level, an altitude that lowers the amount of oxygen in the blood by about 4 percentage points, researchers say.

What happens when plane loses cabin pressure?

Loss of pressure in a plane can come from a hole or leak and results in loss of oxygen. Pilots then need to get the aircraft down to a safe altitude where everyone can breathe normally. Oxygen masks will fall from the plane’s ceiling when the cabin pressure falls below a certain threshold.

Why are cabins pressurized?

Cabins are pressurized to create a safe and comfortable environment for pilots, crew and passengers. Most commercial airplanes fly at around 30,000 to 40,000 feet above sea level. The highly pressurized air inside the cabin will travel outside of the airplane where the pressure is much lower.

What happens if the cabin altitude exceeds the preset limit?

If the cabin altitude exceeds the preset limit, the bellows expands enough to press on the small poppet just to the right of the bellows. This opens the reference chamber to cabin air pressure and causes the outflow valve to close. The valve remains closed as long as the cabin altitude is above the setting of the bellows.

Does an outflow valve increase the temperature of the air?

An outflow valve controls the desired pressure. But with pressure rising doesn’t the temperature rise because you’re compressing air into a space? No, the outflow valve makes sure that the pressure DOESN’T rise, it stays roughly the same (allowing for climb/descent).

How do airplanes maintain air pressure at low altitude?

To maintain the pressure in the cabin equal to that at low altitude, even while the airplane is at 30,000 feet, the incoming air is held within the cabin by opening and closing an outflow valve, which releases the incoming air at a rate regulated by pressure sensors.

Where are the outflow valves on an aircraft pressurized hull?

On transport aircraft there are normally two outflow valves for redundancy, but both will usually be located next to each other, typically at the rear pressure bulkhead, and all of the air in the pressure hull will exit at that spot, all of the pressurized zones being interconnected.