We Will Never Forget
The DVFD Mission
The objective of the Danville Volunteer Fire Department is to provide fire protection, to aid in civil defense emergencies, to aid all concerned in times of distress and emergencies, when and where the services are requested, without recognized boundaries or time, to help eliminate fire hazards, to foster public education of fire prevention and public safety.
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|| July 13 2009 14:21 PM (Read 3895 times)
More Truck Company Ops for the Engine Company Mind
Sunday, July 12 2009 @ 08:46 PM CDT
Contributed by: Jim Moats
Now that some of the “newness” is starting to wear off of the addition to our rolling stock, it is time we look a little deeper into some of the features and issues on this vehicle.
First, the breathing apparatus in use on this truck consists of the new MSA packs with the addition of a “pigtail” located on the hose to the face piece. This connection will allow the breathing apparatus to be tied into the aerial air system. You do not need to have the SCBA cylinder on to use this function; HOWEVER the heads-up display and the PASS device will not be operational. When the aerial air supply is to be placed in service, turn the cylinder on at the base of the ladder. The pressure to the system is pre-adjusted at the regulator to provide the needed flow to the face piece. The regulators on the air system are preset at 60-70 PSI. DO NOT ADJUST THE REGULATORS ON THE CYLINDER AT THE BASE OF THE LADDER OR AT THE CONNECTION AT THE TIP OF THE LADDER. When you get to the top, locate the female Schrader fitting mounted on the ladder and twist it to release the plug inside the fitting. This plug just acts as a safety device to keep the insert clear of debris or water. Take the male Schrader fitting located on the pigtail of the SCBA and push it into the connector on the ladder air system. This is a self-securing fitting that does not manually have to be locked in place. When you are thru with the air, twist the rubber sleeve on the female Schrader fitting, and it will eject your SCBA airline. There is also an eight-foot extension hose in the Driver’s side high side compartment that will give you some extra maneuverability at the tip, with the same fittings. This will eventually be moved to some type of storage bag at the tip for ease of access and use.
Second, the Engineer’s breathing air system consists of basically the same setup with a few exceptions. The pressure at the Engineer’s system is also pre-adjusted at the regulator to provide the needed flow to the face piece. This is also preset at 60-70 PSI. DO NOT ADJUST THE REGULATOR IN THE HIGH SIDE COMPARTMENT. The face piece for the older system still functions as designed. There is an extension hose coming from the regulator in the compartment to a “wye” fitting. At this “wye”, there is an older air fitting that goes to the original mask and a new female Schrader fitting that will allow you to use one of the new MSA SCBA units assigned to that vehicle. There is enough air hose for the Engineer to allow most travel around the work areas of the truck. If you are going to be in heavy smoke conditions, the use of the SCBA fitting is preferred, giving you a means of escape if you have to abandon the vehicle or move further from the area. Always remember SAFETY FIRST, use your judgment when it comes to proximity to the fire and smoke. Remember, someone on the aerial tip might be depending on you to get them out of a situation. When you finish the operation, turn the air cylinders off and breathe the system down. Make sure the new SCBA units get placed back on Ladder 199.
Now, a little about pumping and operating the ladder during pumping operations. A few of the first items to remember during your size-up of the scene and your walk-around setting wheel chocks and outrigger pads, is to close the AERIAL DRAIN at the rear of the truck if you even think you might need the pipe. It just takes a second to do and is easy to forget until you have water pouring out under the rear of the vehicle. Second, do not charge the ladder pipe without verifying that the waterway pin is installed in either position. The ladder pipe can be operated from either the tip or the rescue position, BUT THE PIN MUST BE IN PLACE AND CONFIRMED. Charging the pipe without this pin can cause a deadly jettison of the plumbing off the end of the aerial and was recently responsible for the death of a Command Fire Officer in a nearby state. Once this is confirmed and before you start pumping water, activate the WATER DISCHARGE switch located on the LADDER CONTROL STATION. This opens the valve to the base of the ladder.
During pumping operations, the throttle selector switch on the Engineer’s panel should be placed in the CABLE CONTROL position. This allows the vernier throttle on the panel to control the RPM of the engine and lock out the fast idle setting on the ladder controls. When AERIAL FAST IDLE is used, the ladder operates at approximately 1800 RPM. If this occurs during pumping operations, the sudden increase in RPM’s will most likely cause a dangerously unsafe increase in pump output pressure on the ladder pipe or attack lines causing damage to the equipment or worse, injury to the persons operating the lines. It is also CRITICAL that the Engineer correctly sets the PRESSURE RELIEF VALVE on the pump to act as a safety backup. This will dump most of the pressure if high idle would get activated accidentally. If you do not know how a pressure relief valve works and how to set them on any of the pumpers, get with me and we will do it.
In the case of using the ladder pipe along with hand lines from the aerial pump, the following things need to be kept in mind. The recommended pressures required for operating a fog nozzle are 80PSI for a ladder pipe and 100PSI for hand lines and truck-mounted appliances. Pressures recommended for a solid-bore nozzle are 50PSI for a ladder pipe and 50PSI for hand lines and truck-mounted appliances. Master streams and ladder pipes can withstand more pressure for higher flows, as long as it is done safely. On a ladder pipe, you must concern yourself with NOZZLE REACTION FORCES, which can cause unwanted movement and stress on the aerial. Just like trying to handle a hand line by yourself, the more flow and pressure you have at the tip, the harder it is to move forward or side-to-side. Even a small turn of the ladder nozzle could cause damages to the ladder from the reaction forces. This is also why you open and close the AERIAL DISCHARGE very slowly, and never open or close the WATER DISCHARGE switch at the Ladder Control Station with water flowing.
Pumping the pipe requires the Engineer to know roughly the amount of friction loss in the piping and appliances used on the ladder. A Firefighter’s basic rule of thumb with hose lines is that friction loss or elevation loss equals 5PSI per floor. Take that 5PSI and double it to 10PSI to allow for plumbing and internal friction loss of the Aerial, multiply that by the number of floors, and add the appropriate nozzle pressure to get your desired pump pressure. For example, you have a fog tip nozzle being used at 70 feet, so you take 10PSI multiplied by 7 floors plus 80PSI for the nozzle for a minimum engine discharge pressure of 150PSI. If you were using hand lines along with the pipe, you would need to gate the hand line discharges down to maintain the correct pressure for the lines, usually around 110PSI at the pump. Be alert to sudden changes in discharge pressures if hand lines or ladder pipe get shut down, they will adversely affect each other. It has been told when we have trained with the aerial ladder that if you have to use the ladder pipe, it is really best if you have another engine supply your water. That way you only have to worry about the ladder and not so much the pump. Also, when you are finished with your operation and the vehicle is no longer being used as a pumping engine, place the throttle selector switch back in the AERIAL FAST IDLE position, not in the OFF position. Pull the AERIAL DRAIN at the rear of the truck and allow it to empty before retracting and bedding the aerial.
As before, this information is being provided to our personnel as a training aid. However, this does not take the place of actually operating and experiencing the different situations that you can encounter with this apparatus. If you have questions or want more training or information on this rig, let me know and we will take care of it. As always, be safe and never stop learning.
John Holstein, Chief
Danville Volunteer Fire Department