The Air Source C.A.R.T.

BY JAMES SANDAS

The Air Source C.A.R.T (Continuous Air Resource Transport) is a lightweight, compact, mobile portable air source unit designed to provide a surface air system for rescue firefighters who are operating in a contaminated atmosphere. It can also be used as surface-supplied air when performing underwater diving by supplying air to a manifold block on a scuba unit. The Air Source C.A.R.T. can provide air for the use of pneumatic rescue tools. The cart has two working sides, each working independently. The left side is designated for the use of pneumatic tools while the right side is used specifically for breathing air. The air cart can be deployed in seconds to provide a continuous air source.

Photo 1 by Ray McCormack; 2-7 by author.

It should be noted that if an operation requires an air cart to allow the use of pneumatic tools, then that is what that cart is used for. If we require the use of breathing air to be provided at the operation, a second cart is requested, as we do not use one cart to provide two services.

The air cart uses two self-contained breathing apparatus cylinders. They can be from any manufacturer as well as be any model, size, or pressure rating. To gain maximum usage, the cart should be supplied with two one-hour cylinders.

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There is a directional knob (BLUE) that points to the cylinder in use as well as a remote gauge showing how much air is remaining in the cylinder. There is also a bleeder value on each side to drain the system on completion of an operation and to change out a cylinder when the alarm sounds, indicating the pressure is below 500 pounds per square inch (psi). By switching the knob to the opposite side, you can change out the used cylinder and proceed with the operation.

FOUR AIR TOOL SUPPLY PORTS

The left side of the cart is designed for pneumatic air tool use. There are four air tool attachments, outlets that each work independently from one another. Each can be designated for specific tool use. On this particular air cart, the outlets are designated as follows:

• First outlet–air bag preset @ 116 psi.
• Second outlet–adjustable regulator, 0-250 psi.
• Third outlet–adjustable regulator, 0-250 psi.
• Fourth outlet–air struts, maximum 350 psi.

The high-pressure safety relief device is preset at 350 psi.

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An array of tools, such as high-pressure air bags, air shoring struts, air chisels, pneumatic air hammers, and other air tools, can be operated at the same time at their correct pressures.

FIVE SURFACE SUPPLY AIR PORTS

The right side of the air cart is designed to provide high air flow for up to five air lines. The cart provides an uninterrupted supply of breathing air to be used by rescue personnel. It also has a high-pressure inlet source that allows the use of a compressor or a cascade system as its primary use if there is a prolonged operation.

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The reason for five supply air ports is that we can supply four rescuers as well as one victim with air. If there is an operation that requires that two rescue firefighters go on air, it is a good idea to request a second air cart if additional rescuers are needed for the operation. The maximum number of rescuers we provide on one air cart is two; if all the rescuers were on one cart, we would deplete our air system rapidly. Also, if there were a failure with the air cart, a backup cart would be in the standby mode ready to be placed in operation at a moment’s notice.

There is an adjustable regulating knob above the air ports to either increase or decrease the working pressure. Normal operating pressures for the Air Source C.A.R.T. supplying the SCBA is between 90 and 105 psi. If we need to get the attention of our rescuer on air or if our communications have failed for whatever reason, increasing the pressure on the cart above 122 psi will cause the vibrating alert system in the SCBA to vibrate, thus alerting the rescuer that we either need to make verbal contact or go to alternative means of communicating, possibly using rope tugs.

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The maximum footage on each supply air line is 300 feet at 90 psi. The pressure has a built-in blow-off at the low-pressure safety relief device, which is set at 135 psi. A good practice is to designate each port with a specific color. This color corresponds with the color on the air supply hose. This way we know exactly which rescuer is on which line, and we can determine when each rescuer needs to be changed out if it is a prolonged operation.

When the air cart is placed into operation, an attendant must staff it at all times. The main objective is to make sure the cart is functioning properly, to make sure the rescuer is receiving the proper amount of air, and to change out the cylinders when they run low on air. The moment the rescuer is placed on air, the cart attendant records the time he goes on air, what color is designated for each rescuer on air, and how long the individual has been operating as well as when to change out rescue personnel. Prior to getting the operation up and running, this attendant will have a complete set of standby cylinders at the ready for changing out.

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Air Supply Hose

There is an electronic alarm with visual warning lights and an audible alarm. When the system is turned on, a functional test takes place and a GREEN indicator light glows, indicating that the system is up and functioning properly. A low-pressure alarm will sound when pressures drop below 500 psi in the system. In addition to the alarm’s sounding, the lights will switch from GREEN to RED. Once the air cylinder control value has been switched over, the light system will switch back to GREEN. On shutting the system down, the alarm will sound. To silence the alarm, hold the system test/reset button for five beeps. After five beeps, let go of the button and the system will silence.

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JAMES SANDAS is a 25-year veteran of the Fire Department of New York, where he is assigned to Rescue 2. Previous assignments include Engine Companies 212 and 277 and Ladder 112. His fire service career began 37 years ago as a member of the Hempstead (NY) Volunteer Fire Department, where he has served as the assistant chief of training since 1983. He is also a New York State-certified clinical lab instructor for Nassau County Emergency Medical Services.