劳尔·安格洛（Raul Angulo）
There is a difference between正压通风（PPV）and positive pressure attack (PPA). Both involve controlling the interior flow paths to your advantage, and both include the usage of high-powered 15,000-20,000 cubic feet per minute (cfm) blowers. If your fire department uses PPA or PPV or both, you’re probably familiar with a blower running at full throttle bouncing away from the door opening from its vibration. I call this the “dancing fan.”
我想快速解决两个问题，以抵御批评家。首先，对于那里的纯粹主义者来说，这些大量，气或电动机的正确术语是鼓风机. Afanrefers to the old smoke ejectors that were popular in the 1970s and 1980s–it’s all we had for mechanicalventilation那时。但是，就像2½加仑一样，水加压，便携式灭火器被称为“the can透明(for brevity), the PPV blower and thesmoke ejectorare referred to as “风扇。透明We all know our department cultural routines and nomenclature so there shouldn’t be any confusion when the terms are used interchangeably.
The important difference to understand is that blowers positioned on the exterior of a structure create a higher interior atmospheric pressure (blowing in), where smoke ejectors are usually positioned on the inside and create a negative interior atmospheric pressure (blowing out). But they’re still just fans.
The second issue is, many might say what I’m about to present is a交易技巧，不是演习。我总是回答：“是的。”来吧！这就是您提供信息的方式 - 您可以从任何内容中进行钻探。对我来说，训练是一种更全面的方法，可以共享附带其他教学点的重要信息，而不是简单地提供建议。因此，这是钻探场景。
正压通风和球迷
首先要在风扇的基本知识,including maintenance procedures. See if your firefighters know the make and model as well as the cfm capability. Then go over the placement of the fan on the fireground. The optimum placement for a PPV fan depends on the size of the door opening, the area of the landing (like a front porch), and the size of the fan.
The first objective is to seal the opening of the door with a cone of air. Ideally, a 15,000-20,000 cfm PPV fan should be placed approximately 8-10 feet from the door. However, small porches and stairs can make the ideal place impossible, so do the best you can. The PPV fan can be tilted back approximately 20-30 degrees to aim the center of the air cone towards the center of the door opening. Some ventilation is better than no ventilation. But pose the question to your crew: “How can we still create an effective positive pressure ventilation profile given the design of the structure?” See what they come up with. Multiple PPV fans can be set up in series or next to each other to increase the volume of air directed at the door. Here’s another hint–if you think that the fan needs to be set up in front of a door, your options may be limited. If you think the fan can be set up in anopening, you might have a few more creative options.
第二个目标是确保有足够大小的排气口（门或窗户）用于烟雾和热火气体。足够的尺寸意味着大约是通风开口尺寸的一到三倍。PPV风扇可以比火灾产生的热空气对流电流增加20倍的空气运动量。目标是在相对较短的时间内有效地进行水平通风。内部烟雾条件应立即开始改善，否则可能必须调整排气口。
A Tactical Safety Note:假设PPV风扇是建立在前门on the A side of the building and the exhaust port is a window on the C side of the building–it is always a good idea to have a charged hose line on the exterior C side. Often the hot smoke venting from the exhaust port finds the right air mixture at the window and flames can come roaring out like a blowtorch. It’s quite impressive. However, the siding and soffits on the C side are being exposed to radiant heat and possible direct flame contact. A firefighter needs to flow water above and to each side of the exhaust window and soffits to keep the fire from spreading or entering the attic space. The firefighter is protecting the exposure by keeping surface areas wet. The firefighter should not direct the hose stream back into the window. Allow the fire to vent.
Back to the fans–if your fire department isn’t a fan of PPV fans, stand by. The dangers related to vertical ventilation roof operations combined with lightweight truss construction and synthetic fuels are causing many department to switch to PPV for sheer risk-benefit management. Regardless, the fans get a lot of use and abuse. Even with wheels and handles, the fans aren’t light. Depending on the height of the storage compartment on the apparatus, the fans are constantly being forcefully pushed, pulled, bumped, yanked, bounced, and dropped with countless occasions to remove the fans from the rig and then put them back on. This doesn’t include all the abuse they take on a rugged fireground. After a while, a tread on the wheels starts to wear out and the rubber boots that are on the front leg posts begin to chip, crack, disintegrate, and then fall apart. After a while, the wheel locks either lose their strength or the wheels are too smooth for the brake clamp to grip. Then, when the fan is running at full throttle, you get…the dancing PPV fan!
当发动机运行全油门并且风扇在混凝土或其他一些光滑的表面上时，舞蹈PPV风扇就会发生。发动机的振动和叶片的向后推力将强的离心力启动。如果橡胶靴和车轮锁的强度不足以使风扇在接触点处有摩擦和牵引力，则风扇将开始振动并以顺时针方向弹跳。如果这一动作不引人注目，最终，风扇将摆脱目标开放，这完全破坏了其目的。密封将丢失，更改通风轮廓并立即更改流道。这可能会产生灾难性的结果，尤其是在PPA方案中。在PPA中，您想要风在您的背上。这始终是攻击大火的最安全方法。PPV风扇创建了这种自动回流路径。因此，如果风扇弹跳起来，流道可以逆转自身，将热烟和火送回入场攻击团队。
Since the fan is usually is placed at the entry opening that firefighters are also going to use, it can also get bumped out of position by an advancing hoseline, getting bumped by tools and other equipment, or by firefighters tripping over the fire hoses entering the door space. Unfortunately, hose, tools, firefighters, and the fans are all competing for the same entry opening.
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Raul Angulo and company demonstrate the “dancing fan” effect.
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劳尔·安格洛（Raul Angulo）和公司（Company）为“跳舞粉丝”的问题展示了解决方案。
跳舞迷的解决方案
One solution, and the best solution, is to keep one firefighter posted at the front door with the primary responsibility of manning the fan. However, fire departments with limited staffing may not be able to spare one when other critical tasks still need to be performed.
我要求我的梯子6上的家伙提出解决方案。经过一些成功但不切实际的实验之后，我们想到的是：
If you steal two four-inch hose gaskets from engine company’s workbench and place one underneath each wheel of the PPV fan, it acts like a mini-wheel chock. There is enough thickness in a four-inch gasket that it acts like a curb or a wedge and keeps the wheel in place. For more powerful fans like the 20,000 cfm fans, we had to double-up on the four-inch gaskets. We stacked two gaskets together and secured them with electrical tape. That definitely provided enough of an edge that locked the wheels in place and,voila, we solved the problem of dancing fans. Another member suggested we tie the gaskets to the engine frame so they would always be there…another good idea.
Try this Ladder 6 common sense solution next time you get dancing fans. You’ll see…it really works!
References material:
通风和消防的正压攻击，188金博网网址多少克里斯·加西亚（Kriss Garcia），莱因哈德·考夫曼（Reinhard Kauffmann）和雷·施勒188金宝搏是正规吗（Ray Schelble）（消防工程，2006年）
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劳尔·A·安格洛（Raul A. Angulo）is Captain Emeritus of Ladder Co. 6 and retired from the Seattle (WA) Fire Department with over 35 years of dedicated service. He is an international author andinstructorand serves on the advisory board forFire Apparatus and Emergency Equipmentmagazine.
