1. #1
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    Default NFPA specs for tank baffles

    Anyone out there quote the NFPA specs for tank baffles?

    Is x gal per "cell" in the tank; x% of tank capacity per "cell"; or ______?? . We have an unbaffled tanker and looking at how to add baffles (and do it to standard while we are doing so).

    And no, we don't have $ to purchase NFPA manuals.

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    It's a little complicated to explain as it depends upon the type of baffle system used and the tank shape.

    Basically each baffle shall cover at least 75% of the area enclosed and baffled cells cannot exceed 48" in any one dimension. There are some specific requirements for attachment and bracing also. Unless you have someone that is experienced in the design and installaton, you may create more problems than you will solve.

    Some sugest that baffles are not needed as long as the tanker is full or empty. The problem is when the tank is les than full alowing the sloshing of the water. You might consider this option and shop for a baffled replacement tank.



    Stay Safe
    IACOJ

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    Default NFPA 1901 Standard for Automotive Fire Apparatus (2003)

    Chapter 19 Water Tanks

    19.2.5* All water tanks shall be provided with baffles or swash partitions to form a containment or dynamic method of water movement control.

    19.2.5.1 If a containment method of baffling is used, a minimum of two transverse or longitudinal vertical baffles shall be provided.

    19.2.5.1.1 There shall be a maximum distance of 48 in. (1220 mm) between any combination of tank vertical walls and baffles.

    19.2.5.1.2 Each baffle shall cover at least 75 percent of the area of the plane that contains the baffle.

    19.2.5.2 If a dynamic method of partitioning is used, the tank shall contain vertical transverse and longitudinal partitions.

    19.2.5.2.1 The vertical partitions shall be secured to the top and bottom of the tank.

    19.2.5.2.2 The longitudinal partitions shall extend a minimum of 75 percent of the tank length.

    19.2.5.2.3 The partitions shall be arranged in such a manner that the vertical plane of each partition shall create cells for which no dimension shall exceed 48 in. (1220 mm).

    A.19.2.5 The design of a water tank can be a critical factor in the handling characteristics of fire apparatus. If water is free to travel either longitudinally or laterally in a tank, as would be the case if the tank were half full, a tremendous amount of inertia can be built up that will tend to force the fire apparatus in the direction the water has been traveling. When the water reaches the end of the tank, this sudden application of force can throw the fire apparatus out of control and has been known to cause fire apparatus to turn over or skid when going around a curve or coming to a sudden stop. The only methods for preventing such accidents are to restrict or disrupt the movement of the water so that the inertia will not build up in one direction. This is done with the installation of swash partitions to either contain the water in smaller spaces within the tank (containment method) or disrupt its momentum by changing its direction of motion (dynamic method). The partitions in a containment system create compartments that are interconnected by openings between them so that air and water can flow at the specified rate when filling and emptying the tank. The partitions in a dynamic system are often staggered in an arrangement designed to change the direction of the water and turn it into a turbulent motion that absorbs much of its own energy.

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    There is a plastic "Baffle Ball" on the market. It looks like a giant wiffle ball with flatten sides. It will fit through a 16" diameter opening. They are shipped in two halves to save space on the freight truck. You fasten them together with a stainless band to form the finished shape.

    The manufacturer quoted a lot better deal than a retailer. Enough of them to fill our tankers (tenders) of 2,000 & 3,500 gallons cost about $2,800, or about fifty cents per gallon of tank space. We have not bought any, but might when our rich uncle dies.

    We just use the full or empty rule.

    Surge Buster is another brand that is made of a some flat plastic straps that snap together to form a baffle device.
    Last edited by AC1503; 04-18-2004 at 02:49 AM.

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