1. #1
    Junior Member

    Join Date
    Nov 2003
    Northwest Montana

    Default Severe cold and air brakes

    Just got home from a structure fire. Page out was at 0814, released from scene at 1347. Temperature at page out was -4 degrees.

    Of all the departments and apparatus involved, we only had one mechanical failure: Frozen air lines. The tender had a blow off valve mounted on top of the drive axle beneath the tank. Water spray from the freshly filled tank froze the valve shut, eventually locking up the brake system on the vehicle. Three hours and a service call to a repair shop later, the apparatus was moving again.

    I know that bleeding the air lines is very important for just this reason. I undertsand there is a product that can be injected into the lines to stave off freezing moisture. Does anyone else have any suggestions?

    (The apparatus was not my dept's so I may have some of the fine details mixed but that is the gist of it. I posted this mostly for the object lesson.)

  2. #2
    Forum Member

    Join Date
    Dec 2003


    It sounds like the quick release valve is what was frozen. Many newer trucks have an air dryer that will dramatically help reduce the problem of frozen air lines. There is an air system anifreeze that is basically denatured alcohol. This probably would not have prevented this particular problem. From what you said, the over flow for the tank must be very near this valve. Something that could be done to prevent this is to fabricate a shield around the valve in some way to keep the water from hitting the valve directly.


  3. #3
    Forum Member
    Fire304's Avatar
    Join Date
    Jun 2002
    At the Helm


    I agree with emripp, an alchohal injector would not have helped with external icing. A deflector or shield of some sort needs to be placed over this valve.

    What type of "blow off" valve are you talking about? If it is a safety release valve on a tank then external ice should not affect it (at least as long as it does not need to blow off). The purge valve on the air dryer faces down, should be mounted on a frame rail not under the tank, is well protected, and should have a heater element in it. There is not much else which will freeze a truck's brakes short of water in the brakes from a bad air dryer. In that case, an alchohal injector would help, but the real problem is that water is getting to the primary tank in the first place, it shouldn't with proper maintenance proceedures.
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