SCBA Manual Flashcards
Firefighters should not enter atmospheres that have temperatures exceeding 120 to 130 degrees without protective clothing and full respiratory protection.
If the oxygen content is limited during combustion, large amounts of formic acid, carbolic acid, acetic acid, and ethyl alcohol, along with carbon and tar particle are produced.
It is estimated that 80 percent of all fire casualties succumb o the toxic effects of fire gases before ever being touched by flame.
The following are the primary cause of fire deaths due to toxic gas inhalation: carbon monoxide (CO), carbon dioxide (CO2), sulfur dioxide (SO2), hydrogen cyanide (HCN), hydrogen chloride (HO), and phosgene (COCI2)
Carbon monoxide is slightly lighter than air. At concentrations of 3,200 ppm or .23 percent carbon monoxide is an extremely lethal gas, causing unconsciousness after a thirty minute exposure. When the concentration rises to slightly more than 12,800 ppm 1.28 percent unconsciousness occurs immediately upon exposure and death within one to three minutes
Carbon Dioxides normal concentration in the atmosphere is 330 ppm or .03 percent. When carbon dioxide at 5,000 ppm is breathed in there is a marked increase in respirations along with dizziness sweating and mental excitement. Concentrations of 100,000 to 200,000 ppm may cause death within a few minutes due to paralysis of the respiratory center of the brain.
Hydrogen Sulfide comes from the incomplete combustion of material from living things such as wool, rubber, and hair. It is extremely poisonous and affect the nervous system. Exposure to it causes a rapid breathing rate followed by complete respiratory collapse.
Sulfur Dioxide is formed by complete oxidation of sulfur containing materials such as wool, rubber, some woods. It has an extremely irritating effect on the eyes and respiratory tract, however the quantity produced by combustion is too small to be considered toxic.
Hydrogen cyanide is a highly toxic colorless gas produced by the incomplete combustion of nitrogen containing materials such as wool, nylon, polyurethane foam, rubber, and paper. This gas, which has a noticeable bitter almond odor can cause gasping respiration, muscle spasms, and an increased heart rate. Hydrogen cyanide kills by interfering with the oxygen exchange at the cellular level, preventing tissues and cells from absorbing and using oxygen. Collapse from hydrogen cyanide is sudden, with death occurring very quickly.
Hydrogen chloride and Chlorine- Hydrogen chloride is a colorless gas produced by the combustion of materials containing chlorine. Polyvinyl chloride (PVC) is the most notable source of hydrogen chloride due to its use as electrical insulation and conduit, as well as for the piping of interior water lines (bath, kitchen, laundry room, etc.). PVC may also be found in latex paints, floor coverings (both sheet goods and carpeting), appliance housings (televisions, radios, and stereos), clothing and furniture coverings. Hydrogen chloride affects the human body by causing swelling of the upper respiratory tract, by acting as an irritant to the heart muscle, and by causing irregular heart rhythms. Hydrogen chloride gas when combined with moisture forms hydrochloric acid which can burn and blister mucous membranes of the nose, lining of the lungs, and the tissue in the mouth and throat. The overhaul stage of fire fighting can be the most dangerous in terms of the firefighters exposure to hydrogen chloride. It is during this stage that materials that contain PVC will give off chlorine gas.
Phosgene is a colorless gas produced when refrigerants, such as Freon, used in refrigerators, air conditioners, and beverage coolers come in contact with flame. It has a musty hay odor. It decomposes into hydrochloric acid when in contact with water. The lungs and bronchial tubes are always moist; therefore, damage in the form of burning and blistering these areas will occur to the unprotected firefighter.
The earth’s atmosphere is made up of 21 percent oxygen, 78 percent nitrogen, and 1 percent other inert gases.
Carbon monoxide unites with hemoglobin 210 time more rapidly that oxygen does.
210
The air supply cylinder of the Scott Air Pak fifty is constructed of aluminum inner shell over wrapped with resin impregnated Kevlar or carbon reinforcing fibers. A carbon fiber wrapped cylinder weighs 17.1 lbs. The back frame weighs 9 pounds. All together the air pak and cylinder weigh 26.1 lbs. Does not include EBSS, RIC/UAC or pack tracker
A 60 minute bottle contains 87 cubic feet of air when pressurized to 4500 psi.
The cylinder valve consists of a shut off, a safety relief device (a frangible copperdisc) and a pressure gauge.
Composite cylinders must be hydrostatically tested every 5 years by a certified testing facility to meet Department of Transportation requirements.
The identification for the harness is found on the pressure reducing regulator or on the back frame of the harness and possibly the breathing regulator.
The RIC UAC is for EMERGENCY us only. Improper use of the system may lead to a malfunctioning of the equipment which could cause serious injury or death.
The primary reducing circuit reduces air pressure to 100 psi
The outlet manifold of the pressure reducing regulator is the attachment point for the low pressure hose, and also contains a re-seat able over pressure relief valve set at 225 psi. The overpressure relief valve vents excess pressure to the atmosphere to protect the low pressure hose and breathing regulator from pressure over 225 psi should the primary reducing circuit fail in the open position.
When air pressure remaining in the cylinder drops between 1000 and 1200 psi or the primary pressure reducing circuit fails in the closed position, a transfer valve opens allowing the secondary pressure reducing circuit to function. Te secondary pressure reducing circuit reduces the pressure of the air flowing from the cylinder to the mask mounted regulator from cylinder pressure to 150 psi.
The extra 50 psi is supplied by the secondary pressure reducing circuit to activate the vibra alert alarm and audible end of service time indicator.
The breathing regulator contains a donning switch, purge valve, vibralert alarm, and heads up display. It produces a pressure of approximately .036 to.054 psi above atmospheric pressure inside the face piece.
A constant flow of at least 4.4 cubic feet per minute (225 liters per minute) can be obtained by rotating the knob on the purge valve one half turn counterclockwise.
The vibralert will sound if the air supply drops below 25 percent, if the primary reducing circuit failed, and the secondary pressure reducing circuit is now in operation, or if the primary reducing circuit failed open, and air at more than 225 psi has entered the outlet manifold. In this last case the relief valve of the outlet manifold will open and there will be a loud sound of escaping air.
If the vibralert activates when the SCBA is in use the wearer must immediately notify their officer or partner and leave the contaminated atmosphere.
The heads up display consists of four rectangular lights to represent cylinder pressure at FULL, THREE QUARTERS, ONE HALF, and ONE QUARTER. A fifth round red light, found to the far right of the display, indicates low battery.
Then the Scott Air Pak Fifty is turned on the heads up display will initialize and illuminate all five lights for 20 seconds.
Then the Scott Air Pak Fifty is turned on the heads up display will initialize and illuminate all five lights for 20 seconds.
When full the two green lights will be glowing
When at three quarters a single green light will be glowing
At half the yellow light will flash slowly about once a second
At one quarter the end of service time indicator is indicated by the red light at the far left rapidly flashing at ten times a second
When batteries require changing the Low Battery indicator at the far right of the display will light for 20 seconds and then flash slowly at once a second. When the low batter light is flashing the batteries still have sufficient life to operate the heads up display longer than the one hour cylinder. However the batteries must be changed immediately after ending usage. The heads up display requires two AA batteries for operation. Heads up display batteries are only to be replaced by the air unit or mask room technicians. Regulators are not to be switched from one pack to another.
If the motion sensor does not sense motion of the SCBA for 20 seconds the Pak Alert SE will signal a pre alarm. If there is still no movement after another 10 seconds the full alarm will sound
With fresh alkaline batteries the Pak Alert SE will stay in monitoring mode for 1,000 hours. With fresh alkaline batteries the Pak Alert SE will last in full alarm mode for 8 hours.
Two 9 volt alkaline batteries operate the sensor module. Batteries are only to be replaced by air unit technicians.
Keep antennas of portable radios at least 6 inches away from the control console and the sensor module of the Pak Alert SE and Distress alarm when transmitting.
