New Air Supply Unit For Philadelphia F.D.
features
—Philadelphia fire Department Photo Unit.
Philadelphia fire fighters won’t have to carry numerous replacement SCBA cylinders back and forth anymore during extended operations in high-rise buildings, subway tunnels or other hard-to-reach areas.
Even on the 34th floor of a fire building, the air cylinders can be refilled on the spot through a 400-foot high-pressure line connected to the department’s new portable compressor—Air Unit 1—placed in service on Jan. 26 by Fire Commissioner Joseph R. Rizzo. Air Unit 1 also carries a stock of 42 filled cylinders and a cascade system in case many fire fighters need replacement air supply in a hurry.
Rizzo felt the need of such a unit following high-rise fires in offices of two nationally known insurance companies. The problem was getting replacement cylinders for SCBA to the upper floors. Following the first experience, with elevators out of service, air cylinders were placed on an elevating platform and taken to an upper floor, then carried to a staging area below the fire. But this was exhausting, time-consuming work.
Rizzo felt there had to be a better way. He directed the research and planning division, along with the apparatus officer, to work on a solution.
Out of it came Air Unit 1. The memorandum introducing the unit outlined the definitive area of response upon all requests for breathing air supply in a zone covering basically the center of the city.
However, Air Unit 1 can be dispatched anywhere in Philadelphia upon the request of a chief officer on any fireground operation where the chief anticipates a long duration or extensive air pack services.
The air unit is a custom-designed, air life-support apparatus featuring two air compressors driven by a 3-cylinder aircooled diesel engine operated independently of the apparatus motor.
Compresses and cools
Air flow through the compressors is planned so that the moisture and heat generated during compression will be removed. The compressed air is then discharged to a three-stage purification manifold where carbon monoxide (CO) is removed along with oil vapor, moisture and noxious gases.
In the first compression stage, air enters micronic intake filters and is then compressed and discharged to a second stage, where it is cooled to an ambient temperature to prevent dieseling. Moisture is removed by an intermediate filter along with any oil vapor.
The third stage again cools and cleanses the air of oil vapor and moisture. After the fourth stage of cooling and cleansing, the air is cooled to 50 to 60°F above ambient temperature and is cleansed yet another time.
The pre-cleaned air is filtered through activated charcoal to remove any remaining oil vapor, odor or moisture and is then passed on to the purification cartridges.
In that first compression stage, air is compressed to 40 psi and discharged to the second stage where it is raised to 200 psi. The third stage raises it five times, up to 1000 psi and the fourth stage again raises that five more times to 5000 psi.
Checking for CO
Air is monitored in the purification stage through a CO analyzer. If for any reason—maintenance failure, defective filter, etc.—it was picking up any CO, the unit would sense it immediately upon reaching 10 parts per million, and the motion would shut down the diesel drive in the compressor.
Air Unit 1 carries an eight-bottle cascade system divided into two banks. This system will fill approximately 100 SCBA cylinders when filled to 5000 psi each. The cascade system is divided into a left and right bank in order that cylinders can be filled by the left bank, for example, while the compressor is running to fill the right bank.
Philadelphia is currently operating with air cylinders filled at 2200 psi, but Air Unit 1 is capable of handling the newer 4500 psi cylinders in the future. At present, the relief valve cuts off the supply at 3000 psi, but it can be opened to go to 5000 psi.
The Philadelphia Fire Department has three chemical companies, one located in each of the three fire fighting divisions. In addition to other equipment, each chemical company carries four complete self-contained breathing apparatus, six spare cylinders, and a five-bottle cascade system capable of filling SCBA on the fireground.
It has been found from experience that on the average working fire, a chemical company will fill about 20 SCBA cylinders, so that if Air Unit 1 responds, it will not have to start its compressors.
The stock of 42 cylinders, plus the possible filling of 100 additional from the cascade system would mean that when operating in an area with heavy smoke conditions, or in the presence of a dangerous chemical element, the unit would not often have to be started on the fireground, but the cylinders could be refilled back at the station.
Remote filling possible
A useful feature of Air Unit 1 is a high-rise pressure kit, featuring 400 feet of high pressure line located in a compressor compartment mounted on an electrical take-up reel.
This enables fireground operations to take the line 400 feet from the apparatus, for example, to the 34th floor of a high-rise office or apartment building. Through the use of a pressure gage, shut-off valve, a three-way quick-connect coupling, three SCBA cylinders can be filled. Simultaneously, four cylinders can be filling back at the apparatus at the same time.
The 400-foot hose line is one piece. It is flexible and nonkinking so that it can go around corners, etc., and is tested to withstand 20,000 psi.
This feature alone is expected to eliminate the tedious, exhausting and time-consuming necessity of transporting air cylinders from the working or staging area under fire conditions, back to the outside, and then carrying them up into the building again.
Fuse protection
There is a velocity fuse in the line. If the hose breaks, the velocity fuse will shut off the air supply to the hose and keep it from whipping around. It is very important, when pressurizing the hose line from the valve on the main control that it be opened slowly to avoid activating the velocity fuse. If this happens, it is necessary to shut off the valve, turn it to vent, and start over again slowly after the line is vented.
Operators on both ends of a line operation must be in communication with each other via portable radio.
Whenever the unit is operating its compressors, it is necessary that all doors be kept open because the unit is air-cooled. After 15 minutes of idling the engine on the compressor will shut down automatically.
Other safety checks
Air Unit I features many safety factors. For example, if the compressor develops an oil leak while running, or if the air being compressed is not cooled enough, a sensor will detect the condition and shut down the unit.
The operator works from the rear operating panel, standing on a step. Cylinders to BE filled are placed in tubes and filled in trays. A quick-connect hose is used with the gage on the fill lever. As the operator fills the cylinders, he reads the gage on the fill handle and not on the bottle. Thus, if there is any malfunction, the operator is safe.
The apparatus itself is built on a Chevrolet Bruin chassis powered by a Detroit Diesel 6-71 426-cubic-inch engine and is equipped with an Allison five-speed automatic transmission. It is 11 feet high, 8 feet wide, 22 feet 7 inches long and has a wheelbase of 14 feet 1 inch.
With the inclusion of the new air unit into Philadelphia’s special equipment complement, it will provide an essential and additional element for successful fireground operations.
Fire departments desiring more detailed information on the unit may write to Battalion Chief Frank Scipione, Research and Planning Unit, Philadelphia Fire Administration Building, Third and Spring Garden Sts., Philadelphia, Pa. 19103, and request the apparatus manual section on Air Unit 1.