Archive for August, 2014

The Lost Art of the Fire Service Podcast

Jimm Walsh was just interviewed on the Jumpseat Radio Podcast. The Host Ryan Pennington asked Jimm what VentEnterSearch.com’s tagline The Lost Art of the Fire Service is all about click here to hear the episode. (Once you click on the link, scroll down to under the bio and you’ll see the icon to play the podcast.)

Some of the other topics include:

    Aggressive Search Techniques
    Pro-Active Laddering of the buildings, even if NOT on Fire.
    Tips for each Jumpseat Firefighter to improve their Truck Comapny Functions
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Padlock Twist

Our friend Andrew Brassard from Brotherhood Instructors LLC submitted this video showing the Padlock Twist. A padlocked chain is an extremely common forcible entry situation we may come across. One popular method of defeating this set-up is to try and drive the padlock off the chain by inserting the pike of the halligan into the shackle of the lock, and striking with another tool. However this method is not always the most efficient because the chain tends to act as a shock absorber and absorbs most of the force you are generating into the lock. Another and perhaps more common method is to simply use a saw or bolt cutters to cut the lock… but what if you don’t have a saw on your rig? Or you find yourself operating a long distance from the rig and don’t want to waste time going back to grab a tool?

As you can see in the video, you begin by simply twisting the chain to remove the slack. Once the slack is taken out, you place the forks of the halligan on the shackle of the padlock and keep twisting until the lock fails. The method in the video works really well for both low and medium security padlocks, which are typically the most common we come across due to their low price. The most beneficial part of this method is that it is a single person technique. One common use may be when the outside vent firefighter encounters a chain and padlock when accessing the rear yard at a private dwelling and may only have a hook and halligan to work with.

Knowing how to utilize your tools in a variety of different ways is an essential fireground skill. Simply knowing how to apply the maximum amount of mechanical advantage in different situations will make us more efficient and effective on the fireground.

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Rooftop RF Hazard

Cellular telephone transmission sites are most commonly found on standalone towers, however, building rooftop cellular transmission sites are becoming more and more common. These rooftop transmission sites are certainly something that all firefighters should be aware of. These sites pose a unique threat to firefighters operating on or near the roof in the form of a Radio Frequency (RF) exposure.

Most commonly the cellular transmission sites that are found on towers are made of of 3 sectors (or panels) of antennas 120 degrees from each other. Typically when they are installed on roofs, the antennas consist of 4 sectors (or panels) of antennas, one for each side of the building. Each sector (or panel) is typically made of of 3 high gain antennas, with the middle one dedicated to transmitting and the two outside ones dedicated to receiving. With the increase demand for bandwidth of today’s phones (think internet access), many cellular providers are increasing to 4 antennas per sector.

The most common frequency ranges that are found on cellular transmission sites are in the 824-849MHz, 869-894MHz and 1850-1990-MHz bands. Just for comparison, the most common public safety radios operate in the 769MHz-800MHz, 806-824MHz, and 851-854MHz range. As you can see our radios operate very close to some of the cell phone frequency spectrum, and that’s what that whole re-banding thing was all about. It is worth mentioning that our radios operate at a much lower power (3-5 watts) compared to cellular transmission sites (up to 500 watts) so there are no RF energy issues to be concerned with in regards to our radios.

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One of the most challenging parts of working around these antennas is simply identifying their presence. Often times the antennas are hidden behind fiberglass covers for aesthetic purposes. So easily detecting their presence from the street might be next to impossible. One of the only obvious indications of their presence may like one of the signs shown below posted on the stairwell door providing roof access. This sign is required by the FCC when certain levels of RF energy are present on the roof. Unfortunately this sign will not alert us when we are accessing the roof via the aerial ladder.

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There are many variables when determining the amount of RF energy that is present at each antenna site. It depends on the power output and number of radio channels or transmitters that are present at each site. The FCC permits up to 500 watts per channel, but often times only 100 watts is found in rooftop sites. For our purposes on the fireground it really doesn’t matter the actual power output. We should treat every cellular transmission site like it is capable of producing high levels of RF energy that can significantly hurt us.

The RF energy produced from these antennas is non-ionizing radiation, similar to the energy found in a microwave oven. So the major concern of RF energy exposure is over heating of the human body. Just like those leftovers in the microwave, if your body is in the path of the RF energy you could be heated to a well-done temperature. If you must be around the antenna, a good rule of thumb is to remain behind or under the actual panel of the antenna. The reason this works is because cellular transmission antennas utilize very directional antennas. Essentially all of the energy is focused out the front of the antenna. This is why being below or behind the panel is the safest place if you must be near it for any reason.You never want to allow your head to be in line with the transmission pattern of the antenna. The further away you are, the less energy you will be exposed to. It should go without saying, but never touch the actual antenna.

Besides the RF issues, these cellular sites often present other hazards such as tripping hazards and additional electrical issues. The cable trays mounted on the roof could easily be obscured by smoke causing a tripping hazard. Most radio rooms will also be serviced by a backup generator that will be independent of the buildings primary electrical system. In addition, the site will have battery backup systems as well. So it would be very difficult for us to ensure that all power has been isolated from the equipment.

One of the best things to remember when operating around rooftop cellular antennas is to simply to apply the HazMat mantra of Time, Distance, Shielding. While RF shields are available for certain applications, they have no practical use for us while accessing a rooftop during fireground operations. Simply stay as far away from the antenna as you can, and if for any reason to need to pass in front of one, do it quickly. Time and Distance can minimize your exposure.

If you are curious about the possible location of any cellular transmission sites in your area, there is a free website that will show all sites within a 4 mile radius of a particular address. It may not list every single site, but it’s pretty comprehensive and certainly seems like a fairly accurate tool for planning purposes.

 

The picture above shows a “hidden” cellular transmission site. The four squares are found on each side of the building are each hiding one panel antenna. This particular building has a total of 16 antennas, four on each side. If you found yourself operating on the roof, you could see that your head could be very close to the transmission pattern of the antenna.

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The picture above shows a two different cellular transmission setups. There are two sets of panels that are focused on side A of the building. This just shows that there are two different cellular providers on this building. You can just barely begin to see one of the panels on the D side as well. This particular style of installation is more hazardous to a crew accessing the rooftop from the aerial ladder. You would be perfectly safe to be standing behind these panels since the RF energy is focused out the front. Having said that, if you don’t need to be close to the antenna, simply stay away. Look at the windows just underneath the antenna panels, it just demonstrates how the RF energy is in fact focused straight out.

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The picture above shows another style of roof top transmission sites. This particular setup is more hazardous to the team operating on the roof. Although its hard to tell from the picture. These panels are slightly set back on the roof. This creates a situation where someone could walk directly in front of the panel and directly into the transmission beam. You can also see that the radio room structure has been added to the rooftop of the building. This style of installation would have the trip hazard from the cable trays present in-between the radio room structure and the antennas.

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Color-Coded Cribbing

Assist Chief. Dennis Baker Jr. from Baden (PA) sent in these pictures of how they set up their cribbing. He made sure to point out that Lt. Tim Firich was actually the one who should get the credit for the idea. They color-coded their cribbing based on length. The ones pictured happen to be 18” 6×6’s. As you can see in the picture below the paint color actually goes about an inch onto the side of the cribbing as well. This little addition makes it easy to visually see from a distance that the cribbing tower is square.

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The handles are 1 inch webbing cut at 16 inches long and secured with a fender washer and 1 1/4″ wood screw. They overlapped the webbing and used a soldering pencil to burn the whole for the screw. This will prevent the webbing from unraveling near the screw hole.

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The idea of color-coding could be implemented a few different ways: either length or lumber size. Even wedges could be coded with different color paint, or even a different color of webbing. For example if you painted your 4×4’s red, the 4×4 wedges could also be red, but with a different color webbing. The important thing is not of over think it. Come up with a standardized marking system that works for you and your agency.

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Building Construction Prop

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Bud Henkels from the Montgomery County (PA) Fire Academy sent in this amazing building construction prop that he built for his Firefighter Awareness to Wood Frame Construction class. The focal point of the presentation is this scale model (1 ” = 1′) that shows the students wood frame construction from foundation to ridgepole.

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On one side it incorporates modern day platform framing and on the other side, later day balloon framing. Having both different construction types present make it easy to show the differences with each style. The prop includes the ability to add a real time smoke conditions that demonstrate how differently smoke and fire can travel through each type of construction. While the prop is certainly a major part of it, the program also includes a 3-hour power point program that focuses on building terminology and other building constriction methods.

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Bud’s previous experience as a carpenter and contractor certainly shows through with this quality craftsmanship. Wile making a quality prop like this will certainly take some time; it doesn’t have to cost much money. There is a good chance that someone around your firehouse has the talent and ability to make something similar. This prop, sitting on a table in the firehouse or training room can be referred to during many formal classes, and even more importantly those informal kitchen table classes. Instead of doing some third grade quality drawing on the dry erase board; pointing something out on a prop like this would certainly enhance the learning opportunity.

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