DOC AIRBUS | AMM A320FCABIN ATTENDANTS PORTABLE DEVICES - DESCRIPTION AND OPERATION
** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL
1. General
The cabin-attendants' portable oxygen equipment is installed at different locations in the cabin. It supplies oxygen to the passengers and crew for first-aid treatment. It also lets the cabin attendants move about the cabin and have a supply of oxygen at the same time. The portable oxygen equipment is made up of portable oxygen cylinders with continuous-flow oxygen masks and Protective Breathing Equipment.
** ON A/C NOT FOR ALL The cabin-attendants' portable oxygen equipment is installed at different locations in the cabin. It supplies oxygen to the passengers and crew for first-aid treatment. It also lets the cabin attendants move about the cabin and have a supply of oxygen at the same time. The portable oxygen equipment is made up of portable oxygen cylinders with continuous-flow oxygen masks and Protective Breathing Equipment.
2. Component Location
Cabin Attendants Portable-Oxygen Equipment ** ON A/C NOT FOR ALL
Cabin Attendants Portable-Oxygen Equipment ** ON A/C NOT FOR ALL
Cabin Attendants Portable-Oxygen Equipment ** ON A/C NOT FOR ALL
Cabin Attendants Portable-Oxygen Equipment ** ON A/C NOT FOR ALL
Cabin-Attendants Portable-Oxygen Equipment ** ON A/C NOT FOR ALL
Cabin-Attendants Portable-Oxygen Equipment ** ON A/C NOT FOR ALL
Cabin-Attendants Portable-Oxygen Equipment ** ON A/C NOT FOR ALL
Cabin-Attendants Portable-Oxygen Equipment ** ON A/C NOT FOR ALL
Cabin-Attendants Portable-Oxygen Equipment ** ON A/C NOT FOR ALL
Cabin-Attendants Portable-Oxygen Equipment ** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL Cabin Attendants Portable-Oxygen Equipment ** ON A/C NOT FOR ALL Cabin Attendants Portable-Oxygen Equipment ** ON A/C NOT FOR ALL Cabin Attendants Portable-Oxygen Equipment ** ON A/C NOT FOR ALL Cabin Attendants Portable-Oxygen Equipment ** ON A/C NOT FOR ALL Cabin-Attendants Portable-Oxygen Equipment ** ON A/C NOT FOR ALL Cabin-Attendants Portable-Oxygen Equipment ** ON A/C NOT FOR ALL Cabin-Attendants Portable-Oxygen Equipment ** ON A/C NOT FOR ALL Cabin-Attendants Portable-Oxygen Equipment ** ON A/C NOT FOR ALL Cabin-Attendants Portable-Oxygen Equipment ** ON A/C NOT FOR ALL Cabin-Attendants Portable-Oxygen Equipment ** ON A/C NOT FOR ALL | ------------------------------------------------------------------------------- |
| FIN | FUNCTIONAL DESIGNATION | PANEL|ZONE|ACCESS | ATA |
| | | | | DOOR | REF. |
| ------------------------------------------------------------------------------- |
| CYLINDER-PORTABLE OXYGEN 200 35-32-42 |
| MASK-ASSY OXYGEN 200 35-32-00 |
| HOOD-SMOKE 200 35-32-52 |
| MASK-DEMONSTRATION 200 35-32-00 |
| TOOL-MANUAL RELEASE 200 35-32-00 |
3. Description
A. Portable Oxygen Cylinder
Portable Oxygen Cylinder ** ON A/C NOT FOR ALL
Portable Oxygen Cylinder ** ON A/C NOT FOR ALL
Portable Oxygen Cylinder ** ON A/C NOT FOR ALL
Portable Oxygen Cylinder ** ON A/C NOT FOR ALL Portable Oxygen Cylinder ** ON A/C NOT FOR ALL Portable Oxygen Cylinder ** ON A/C NOT FOR ALL (1) The oxygen source is a high-pressure cylinder with a capacity of 310 l (11 cubic ft) Normal Temperature Pressure Dry (NTPD) at a pressure of 124 bar (1800 psi). The cylinders are installed in brackets which have quick-release clamps.
(2) The oxygen cylinder has a head that is made up of the following components.
(a) A direct-reading pressure gage to show the cylinder pressure.
(b) A high-pressure relief valve with a rupture disc. This is installed in the high pressure chamber of the pressure regulator. The disc ruptures at a pressure of between 186.2 bar (2700 psi) and 206.8 bar (3000 psi). This pressure would be the result of an unusual rise in temperature.
(c) A low-pressure relief valve. This is installed in the low pressure chamber of the pressure regulator. When the outlet pressure is more than 6.2 bar (90 psi) the relief valve will open. Oxygen is released and the outlet pressure decreases. The relief valve closes when the pressure decreases to 6.2 bar (90 psi ) again.
(d) A rotary ON/OFF valve to control the flow of oxygen into the high-pressure chamber of the pressure regulator.
(e) A filling valve directly connected to the high-pressure chamber of the pressure regulator. This valve permits the filling of the oxygen bottle at a controlled flow.
(f) A pressure regulator to give a low-pressure of between 2.4 bar (35 psi) and 5.9 bar (85 psi).
(g) There are two outlet connections. An uncalibrated outlet for the full-face smoke mask and a constant flow outlet for the continuous-flow mask.
(3) The oxygen source is a high-pressure cylinder with a capacity of 11 cubic ft (311 l) Normal Temperature Pressure Dry (NTPD) at a pressure of 1850 psi (127.55 bar). The oxygen cylinders are installed in brackets which have quick-release clamps.
(4) The oxygen cylinder has a head that is made up of the following components:
(a) A direct-reading pressure gage to show the cylinder pressure.
(b) A high-pressure safety valve with a rupture disc. This is installed in the high pressure chamber of the pressure regulator. The disc ruptures at a pressure of between 2775 psi (191.33 bar) and 3083 psi (212.57 bar). This pressure can be the result of an unusual rise in temperature.
(c) A low-pressure safety relief valve is installed in the low pressure chamber of the pressure regulator. When the outlet pressure is more than 90 psi (6.21 bar) the relief valve will open. Oxygen is released and the outlet pressure decreases. The relief valve closes when the pressure decreases to 90 psi (6.21 bar).
(d) A rotary ON/OFF valve to control the flow of oxygen from the high-pressure chamber to the low-pressure chamber of the pressure regulator.
(e) A pressure regulator to give a controlled low-pressure flow of oxygen. The pressure regulator has two flow positions, 2 l/min or 4 l/min.
(f) A filling valve directly connected to the high-pressure chamber of the pressure regulator. This valve permits the filling of the oxygen cylinder at a controlled rate.
(g) A constant-flow outlet for the continuous-flow mask.
(5) A mask stowage bag is installed on the oxygen cylinder. The stowage bag contains a continuous-flow oxygen mask, which is connected to the constant-flow outlet.
(6) The oxygen cylinder has a carrying strap.
(7) The oxygen source is a high-pressure cylinder with a capacity of 310 l (11 cubic ft) Normal Temperature Pressure Dry (NTPD) at a pressure of 1850 psi (127.55 bar). The cylinder is installed in brackets which have quick-release clamps.
(8) The oxygen cylinder has a pressure regulator that has the components that follow:
(a) A direct-reading pressure gage to show the cylinder pressure.
(b) A high-pressure safety relief valve with a rupture disc, that is installed in the high pressure chamber of the pressure regulator. The disc ruptures at a pressure 3089 psi (213 bar). This pressure can be the result of an unusually increased temperature.
(c) A low-pressure safety relief valve, that is installed in the low pressure chamber of the pressure regulator. When the outlet pressure is more than 80 psi (5.5 bar) the relief valve will open. Oxygen is released and the outlet pressure decreases. The relief valve closes when the pressure decreases to 80 psi (5.5 bar).
(d) A rotary ON/OFF valve to control the flow of oxygen from the high-pressure chamber to the low-pressure chamber of the pressure regulator.
(e) A flow selector valve has two flow positions: 2 l/min or 4 l/min.
(f) A filling valve directly connected to the high-pressure chamber of the pressure regulator. This valve lets you fill the oxygen bottle at a controlled rate.
(g) A constant-flow outlet for the continuous-flow mask.
(9) A mask stowage bag is installed on the oxygen cylinder. The stowage bag contains a continuous-flow oxygen mask, which is connected to the constant-flow outlet.
(10) The oxygen cylinder has a carrying strap.
(11) The oxygen source is a high-pressure cylinder with a capacity of 202 l (7.15 cubic ft) Normal Temperature Pressure Dry (NTPD) at a pressure of 1850 psi (127.55 bar). The cylinder is installed in brackets which have quick-release clamps.
(12) The oxygen cylinder has a pressure regulator that has the components that follow:
(a) A direct-reading pressure gage to show the cylinder pressure.
(b) A high-pressure safety relief valve with a rupture disc, that is installed in the high pressure chamber of the pressure regulator. The disc ruptures at a pressure 3089 psi (213 bar). This pressure can be the result of an unusually increased temperature.
(c) A low-pressure safety relief valve, that is installed in the low pressure chamber of the pressure regulator. When the outlet pressure is more than 79.78 psi (5.50 bar) the relief valve will open. Oxygen is released and the outlet pressure decreases. The relief valve closes when the pressure decreases to 79.78 psi (5.50 bar).
(d) A rotary ON/OFF valve to control the flow of oxygen from the high-pressure chamber to the low-pressure chamber of the pressure regulator.
(e) A flow selector valve has two flow positions: 2 l/min or 4 l/min.
(f) A filling valve directly connected to the high-pressure chamber of the pressure regulator. This valve lets you fill the oxygen bottle at a controlled rate.
(g) A constant-flow outlet for the continuous-flow mask.
(13) A mask stowage bag is installed on the oxygen cylinder. The stowage bag contains a continuous-flow oxygen mask, which is connected to the constant-flow outlet.
(14) The oxygen cylinder has a carrying strap.
B. Cabin-Attendants Portable Devices
(1) Protective Breathing Equipment (PBE)
Protective Breathing Equipment ** ON A/C NOT FOR ALL
Protective Breathing Equipment ** ON A/C NOT FOR ALL
Protective Breathing Equipment ** ON A/C NOT FOR ALL
Protective Breathing Equipment ** ON A/C NOT FOR ALL
Protective Breathing Equipment ** ON A/C NOT FOR ALL
Protective Breathing Equipment ** ON A/C NOT FOR ALL
The PBE gives the cabin attendants protection from smoke and dangerous gases.
Protective Breathing Equipment ** ON A/C NOT FOR ALL Protective Breathing Equipment ** ON A/C NOT FOR ALL Protective Breathing Equipment ** ON A/C NOT FOR ALL Protective Breathing Equipment ** ON A/C NOT FOR ALL Protective Breathing Equipment ** ON A/C NOT FOR ALL Protective Breathing Equipment ** ON A/C NOT FOR ALL (2) The PBE has these components:
The hood also gives protection in the breast area. This protective part includes the KO2 cartridge with the breathing bag itself.
- A hood with breathing bag protection, a relief valve, a visor and a neck seal
- A KO2 cartridge with starter, a relief outlet and a breathing bag
- An inner mask with anti-suffocation valve, straps and a voice transmitter.
The hood also gives protection in the breast area. This protective part includes the KO2 cartridge with the breathing bag itself.
(3) A PBE contains these components:
- A double layer hood which is attached to the life support unit at the rear of the hood, a head harness, a flexible membrane which gives a seal between the hood and the neck and a transparent visor
- A life support unit which contains a chemical oxygen generator, a scrubber, a venturi nozzle, a vent valve and a housing
- A case with inspection window and hand-carry strap.
(4) A PBE has the following components:
The hood with the visor encloses, when put on, the head of the user. The opening for the neck makes a seal when the PBE is used.
- A hood with breathing bag protection, a visor and a neck seal that operates also as a relief valve
- Two oxygen cylinders
- A Service/End-of-Service indicator light
- Lithium hydroxide (LiOH) scrubber panels.
The hood with the visor encloses, when put on, the head of the user. The opening for the neck makes a seal when the PBE is used.
(5) The PBE is packed in a vacuum-sealed bag, which is packed in a transport/storage box.
(a) The box is equipped with:
- A good condition indicator (serviceable color is green)
- A cover secured with a tamper seal
- An instruction pictogram
- An identification plate which gives the date of its manufacture.
(b) To gain access to the vacuum sealed bag it is necessary to break the tamper seal and open the box cover.
(6) A PBE has the following components:
- A hood with visor and silicone neck seal
- A face piece mask connected to the KO2 cartridge
- A KO2 cartridge which reacts with water to form oxygen and absorb carbon dioxide.
(7) The chemical generator will supply oxygen to the hood for approximately fifteen minutes.
(8) The two oxygen cylinders will supply oxygen to the hood for approximately 15 minutes.
(9) The PBE has these components:
- A visor treated with a demister and anti-scratch compound
- A sealed collar at neck level
- An oxygen container with an automatic priming system and a fused valve
- A carbon dioxide absorption system which uses soda lime to trap the carbon dioxide contained in the gas breathed in a closed circuit
- A pressure control valve
- A phonic membrane.
(a) The technical characteristics are:
- Supply: 15 minutes minimum
- Oxygen capacity: 39 l (NTPD)
- Filled pressure: 150 bars (2175 psi)
- Respiratory flow: 30 l/min (BTPS).
(10) P/N E28180 series:
The PBE is packed in a vacuum-sealed bag which is packed in the storage/transport container.
The storage/transport container has:
The hood also gives protection in the breast area. This protective part includes the KO2 cartridge with the breathing bag itself.
The KO2 cartridge will supply oxygen to the hood for approximately fifteen minutes.
The PBE is packed in a vacuum-sealed bag which is packed in the storage/transport container.
The storage/transport container has:
- An identification plate
- An instruction pictogram
- An inspection window
- A locking clamp secured with tamper seal.
- A hood with relief valve, a visor and a neck seal
- A KO2 cartridge with starter, a relief outlet valve and a breathing bag
- An inner mask with anti-suffocation valve, straps and a voice transmitter.
The hood also gives protection in the breast area. This protective part includes the KO2 cartridge with the breathing bag itself.
The KO2 cartridge will supply oxygen to the hood for approximately fifteen minutes.
C. Continuous-Flow Oxygen Mask
Continuous-Flow Oxygen Mask ** ON A/C NOT FOR ALL
Continuous-Flow Oxygen Mask ** ON A/C NOT FOR ALL
Continuous-Flow Oxygen Mask ** ON A/C NOT FOR ALL
Continuous-Flow Oxygen Mask ** ON A/C NOT FOR ALL Continuous-Flow Oxygen Mask ** ON A/C NOT FOR ALL Continuous-Flow Oxygen Mask ** ON A/C NOT FOR ALL (1) A continuous-flow oxygen mask has these components:
- A face piece that covers your nose and mouth (oro-nasal face piece)
- A diluter valve
- An exhale valve
- An inhale valve
- A reservoir bag with integrated flow indicator
- A flexible supply hose with a connector.
(2) A continuous-flow oxygen mask has these components:
- An elastic headband
- A face piece as a cover for the user's nose and mouth
- A diluter valve (ambient air valve)
- An exhalation valve
- An inhalation valve
- A reservoir bag
- A flexible supply hose with a connector
- An in-line flow indicator.
(3) A continuous-flow oxygen mask has these components:
- A head strap assembly
- A face piece
- A lanyard assembly or a stringer
- An exhalation valve
- An ambient air valve
- An inhalation valve
- A cord
- A reservoir bag with the inflatable flow indicator
- A ring tube
- An anti-kink spring or a stop tube or an in-line flow indicator or an oxygen flow actuator
- A flexible supply hose with end fitting.
4. Operation
A. Protective Breathing Equipment (PBE)
Smoke Hood:
When the smoke hood is put on, the annular container in the hood releases the necessary quantity of oxygen for the person. When you breathe a slight noise will be heard when the oxygen flows. When the noise of the oxygen flow stops the hood must not be used.
The hood has two compartments. One compartment is for the head, the other is used as a lung. When you breathe, some gas flows from one compartment to the other through the absorption system. The absorption system traps the carbon dioxide contained in the expired breath through a layer of soda lime.
A pressure control valve prevents an increase of pressure in the hood (pressure limit 1.5 mbar (0.02 psi)).
A phonic membrane allows the crew member to communicate easily.
When the equipment is in the serviceable condition, the condition-indicator is green. When the condition indicator is red the equipment is no longer serviceable.
Smoke Hood:
The oxygen flow starts when the user moves quickly the two oxygen cylinders apart. One oxygen cylinder releases oxygen quickly. The smoke hood operates correctly when this oxygen cylinder inflates the smoke hood in less then two minutes.
The second oxygen cylinder releases oxygen more slowly. A flashing green light in the Service/End-of-Service Indicator light comes on. This tells the user that the second oxygen cylinder operates correctly.
When put on, the smoke hood protects the wearer for up to 15 minutes. Both oxygen cylinders release the oxygen fully in 8 to 10 minutes. Enough oxygen stays in the smoke hood for the full specified 15 minutes of respiration protection.
The smoke hood operates at a positive pressure. The neck seal operates also as a relief valve to prevent too much pressure inside the Smoke Hood.
Special fabric panels inside the Smoke Hood control the quantity of the carbon dioxide. These panels contain a dustless lithium hydroxide absorbent sealed inside a double-walled membrane. These panels keep carbon dioxide concentrations at safe levels during the hood's 15 minute useful life.
Person wearing a smoke hood can speak with other people up to about 13 ft (4 m).
The smoke hood useful life has expired and must be removed when:
During the donning sequence, the chlorate candle is automatically actuated. The adjustment straps are pulled to secure the oro-nasal mask cone against the face. When the neck seal is positioned, the oxygen generated by the chlorate candle inflates the Smoke Hood. It provides adequate breathing volume and accomplish some purging of the Smoke Hood with any excess gas generation. When the wearer breathes through the mask cone, the exhaled breath is directed through the KO2 canister. It removes water fume and carbon dioxide and adds oxygen before the gas is returned to the interior of the smoke hood. The breathing cycle continues until the KO2 bed is removed. It results in a loss of active oxygen generation capability and rapid increase in internal temperature and release of moisture through the KO2 bed. The loss of oxygen generation capability results in a reduction of the interior volume of the smoke hood. Inhalation becomes difficult and the smoke hood should be removed.
The PBE is a self contained device. It has a supply of breathable gas. The supply adds oxygen to a closed circuit of breathe to renew the expired air.
The oxygen is made by an exothermic chemical effect. The KO2 of the cartridge effects with the CO2 and the humidity of the expired air.
Smoke Hood P/N E28180-20-0011:
The PBE is a self contained device. It contains a supply of breathable gas. A close circuit of breathe gives this supply of breathable gas. The supply adds oxygen to recycle the expired air to make it breathable again.
The oxygen is made by an exothermic chemical effect. The KO2 of the cartridge effects with the CO2 and the humidity of the expired air.
Smoke Hood:
The smoke hood works with a semi-closed circuit. When the Pull to Actuate ring is disengaged from the unit, low pressure oxygen is produced by an oxygen generator. The oxygen flows from the generator into a venturi nozzle which pulls the hood gas through the CO2 scrubber. The scrubbed flow and the added oxygen are released into the hood to mix with the hood gas.
Smoke Hood:
When the smoke hood is put on, the annular container in the hood releases the necessary quantity of oxygen for the person. When you breathe a slight noise will be heard when the oxygen flows. When the noise of the oxygen flow stops the hood must not be used.
The hood has two compartments. One compartment is for the head, the other is used as a lung. When you breathe, some gas flows from one compartment to the other through the absorption system. The absorption system traps the carbon dioxide contained in the expired breath through a layer of soda lime.
A pressure control valve prevents an increase of pressure in the hood (pressure limit 1.5 mbar (0.02 psi)).
A phonic membrane allows the crew member to communicate easily.
When the equipment is in the serviceable condition, the condition-indicator is green. When the condition indicator is red the equipment is no longer serviceable.
Smoke Hood:
The oxygen flow starts when the user moves quickly the two oxygen cylinders apart. One oxygen cylinder releases oxygen quickly. The smoke hood operates correctly when this oxygen cylinder inflates the smoke hood in less then two minutes.
The second oxygen cylinder releases oxygen more slowly. A flashing green light in the Service/End-of-Service Indicator light comes on. This tells the user that the second oxygen cylinder operates correctly.
When put on, the smoke hood protects the wearer for up to 15 minutes. Both oxygen cylinders release the oxygen fully in 8 to 10 minutes. Enough oxygen stays in the smoke hood for the full specified 15 minutes of respiration protection.
The smoke hood operates at a positive pressure. The neck seal operates also as a relief valve to prevent too much pressure inside the Smoke Hood.
Special fabric panels inside the Smoke Hood control the quantity of the carbon dioxide. These panels contain a dustless lithium hydroxide absorbent sealed inside a double-walled membrane. These panels keep carbon dioxide concentrations at safe levels during the hood's 15 minute useful life.
Person wearing a smoke hood can speak with other people up to about 13 ft (4 m).
The smoke hood useful life has expired and must be removed when:
- It deflates and touches the users head and face.
- The Service/End-of-Service indicator light flashes red.
During the donning sequence, the chlorate candle is automatically actuated. The adjustment straps are pulled to secure the oro-nasal mask cone against the face. When the neck seal is positioned, the oxygen generated by the chlorate candle inflates the Smoke Hood. It provides adequate breathing volume and accomplish some purging of the Smoke Hood with any excess gas generation. When the wearer breathes through the mask cone, the exhaled breath is directed through the KO2 canister. It removes water fume and carbon dioxide and adds oxygen before the gas is returned to the interior of the smoke hood. The breathing cycle continues until the KO2 bed is removed. It results in a loss of active oxygen generation capability and rapid increase in internal temperature and release of moisture through the KO2 bed. The loss of oxygen generation capability results in a reduction of the interior volume of the smoke hood. Inhalation becomes difficult and the smoke hood should be removed.
The PBE is a self contained device. It has a supply of breathable gas. The supply adds oxygen to a closed circuit of breathe to renew the expired air.
The oxygen is made by an exothermic chemical effect. The KO2 of the cartridge effects with the CO2 and the humidity of the expired air.
Smoke Hood P/N E28180-20-0011:
The PBE is a self contained device. It contains a supply of breathable gas. A close circuit of breathe gives this supply of breathable gas. The supply adds oxygen to recycle the expired air to make it breathable again.
The oxygen is made by an exothermic chemical effect. The KO2 of the cartridge effects with the CO2 and the humidity of the expired air.
Smoke Hood:
The smoke hood works with a semi-closed circuit. When the Pull to Actuate ring is disengaged from the unit, low pressure oxygen is produced by an oxygen generator. The oxygen flows from the generator into a venturi nozzle which pulls the hood gas through the CO2 scrubber. The scrubbed flow and the added oxygen are released into the hood to mix with the hood gas.
B. Continuous-Flow Oxygen Mask
The continuous-flow oxygen mask is connected to the oxygen cylinder and the ON/OFF valve turned on. The oxygen flows through the supply hose into the reservoir bag. The reservoir bag inflates and the flow indicator shows green.
When the person breathes in, the oxygen flows from the reservoir bag through the inhalation valve into the face piece. When the oxygen in the reservoir bag is used, the ambient air valve opens and lets ambient air into the face piece.
When the person breathes out, the inhalation and the ambient air valves close and the exhaled air goes through the exhalation valve. Oxygen flows into the reservoir bag for the next breathing cycle when the person is breathing out.
The oxygen mask is connected to the oxygen cylinder and the ON/OFF valve set to ON. The oxygen flows through the supply hose into the reservoir bag. If the flow indicator is installed, it will show green color while oxygen flows and clear when there is no flow.
When the person breathes, the oxygen flows through the inhalation valve and fills the face piece of the oxygen mask. As soon as the oxygen in the bag is decreased by inhalation, ambient air is pull through the dilution valve to complete the inhalation cycle. During exhalation, slight pressure from the person's lungs will open the exhalation valve and exhaust the unwanted gases to the atmosphere.
The continuous-flow oxygen mask is connected to the oxygen cylinder and the ON/OFF valve turned on. The oxygen flows through the supply hose into the reservoir bag. The reservoir bag inflates and the flow indicator shows green.
When the person breathes in, the oxygen flows from the reservoir bag through the inhalation valve into the face piece. When the oxygen in the reservoir bag is used, the ambient air valve opens and lets ambient air into the face piece.
When the person breathes out, the inhalation and the ambient air valves close and the exhaled air goes through the exhalation valve. Oxygen flows into the reservoir bag for the next breathing cycle when the person is breathing out.
The oxygen mask is connected to the oxygen cylinder and the ON/OFF valve set to ON. The oxygen flows through the supply hose into the reservoir bag. If the flow indicator is installed, it will show green color while oxygen flows and clear when there is no flow.
When the person breathes, the oxygen flows through the inhalation valve and fills the face piece of the oxygen mask. As soon as the oxygen in the bag is decreased by inhalation, ambient air is pull through the dilution valve to complete the inhalation cycle. During exhalation, slight pressure from the person's lungs will open the exhalation valve and exhaust the unwanted gases to the atmosphere.