Airplane General, Emergency Equipment, Doors, Windows -Systems Description
737 Operations Manual
Passenger Oxygen System
The passenger oxygen system is supplied by individual chemical oxygen generators located at each Passenger Service Unit (PSU). Three or four continuous flow masks are connected to each generator. A generator with two masks is located above each attendant station and in each lavatory.
The system is activated automatically by a pressure switch at a cabin altitude of approximately 14,000 feet or when the Passenger Oxygen Switch on the aft overhead panel is positioned to ON. When the system is activated, the PASS OXY ON light illuminates and OVERHEAD illuminates on the Master Caution System.
Activating the system causes the masks to drop from the stowage compartments. The oxygen generators are activated when any mask in the unit is pulled down. Pulling one mask down causes all masks in that unit to come down and 100% oxygen flows to all masks. A green in–line flow indicator is visible in the transparent oxygen hose whenever oxygen is flowing to the mask. Oxygen flows for approximately 12 minutes and cannot be shut off. If the passenger oxygen is activated and a PSU oxygen mask compartment does not open, the masks may be dropped manually.
PSU Oxygen Mask Compartment
DOOR LATCH
MECHANISM

OXYGEN HOSE

CHEMICAL OXYGEN GENERATOR
RELEASE FIRING PIN
GENERATOR LANYARD OXYGEN MASK LANYARD

FWD
PSU
OXYGEN MASK DOOR (SHOWN OPEN)
RESERVOIR BAG MASK
WARNING: When using passenger oxygen, the “NO SMOKING” sign should be strictly observed. Once the generator is activated, the flow of oxygen is constant, whether or not the mask is being worn.
Airplane General, Emergency Equipment, Doors, Windows -Systems Description
737 Operations Manual
WARNING: Do not use passenger oxygen with cabin altitude below 14,000 feet when smoke or an abnormal heat source is present. The use of passenger oxygen does not prevent the passengers from inhaling smoke. Air inhaled is a mixture of oxygen and cabin air.
Passenger Portable Oxygen
First aid and supplemental portable oxygen cylinders are installed at suitable locations in the passenger cabin. The cylinders are fitted with a pressure guage, pressure regulator and an on–off valve. The cylinders are pressurized to 1800 psi. At this pressure and a temperature of 70° Fahrenheit (21° Celsius), the cylinders have a capacity of 4.25 cubic feet (120 liters) of free oxygen. Two continuous flow outlets are provided on each cylinder, one regulates flow at two liters per minute for walk–around; the second outlet provides flow at four liters per minute. The four–liter flow is used for first aid.
Duration can be determined by dividing capacity by outflow (120 liters divided by 4 liters/minute = 30 minutes).
Passenger Portable Oxygen Equipment
CONSTANT FLOW
OUTLET (4 LITER FLOW)

CONSTANT FLOW OUTLET (2 LITERFLOW)
PRESSURE REGULATOR
ON-OFF VALVE
PRESSURE GAUGE
PLACARD
OXYGEN CYLINDER
Copyright . The Boeing Company. See title page for details.
1.40.10  December 1, 2000

Airplane General, Emergency Equipment, Doors, Windows -Systems Description
737 Operations Manual
Fire Extinguishers
Fire extinguishers are located in the flight deck and passenger cabin.
Water Fire Extinguishers
Water fire extinguishers contain a solution of water mixed with antifreeze. The container is pressurized by a CO2 cartridge when the extinguisher handle is rotated fully clockwise. The extinguisher should be used on fabric, paper or wood fires only.
To use the water fire extinguisher:
.
remove from stowage

.
rotate handle fully clockwise

.
aim at base of fire and press trigger.

CAUTION: Do not use on electrical or grease type fires. Water Fire Extinguisher

Halon (BCF) Fire Extinguishers
Halon (BCF) fire extinguishers contain a liquefied gas agent under pressure. The pressure indicator shows an acceptable pressure range, a recharge range, and an overcharged range. A safety pin with a pull ring prevents accidental trigger movement. When released the liquefied gas agent vaporizes and extinguishes the fire. The extinguisher is effective on all types of fires, but primarily on electrical, fuel and grease fires.