Calorimiter burning the wires

Discussion in 'Supporting Biology' started by Jburns, Nov 8, 2019.

  1. Hey guys,

    Our calorimeter is a bit dodgy at the moment, seems to not work and when it does it causes enough fire in there to melt the wires.

    So problem 1, how do I get it to work constantly as even with new wiring the element does not seem to heat up every time?

    Problem 2 is how do I stop it becoming a large fire inside the calorimeter? Do I need to just reduce the O2 flow or is it that I need to reduce the amount of food that is burning?

    Any pictures of your set ups would be great!
     
  2. Is it one of the old glass ones?

    Mine you make the starter with some 32swg nicrome wound round a match, not sure it's reusable.

    but not used it for a while.
     
  3. Yep its an old glass one. We have a small canister of elements for it. To me it looks like the block the power leads come into and then connect to the element seems to have issues but it looks clear just doesn't seem to work as well as it used to
     
  4. As Paul said, 32SWG nichrome wire, about 5 or 6 turn coil - make sure the coils do not touch one another (making your own is MUCH cheaper than buying them in). Pop an ammeter in the circuit and adjust the power supply to give about 5A, this seems to work for us, but it depends on what fuel you are using. Switch it off as soon as the food/fuel catches fire. If the coil does not heat up, it's usually because someone has turned the power supply up too high and blown the fuse or the thermal cutout. We usually get 8 to 10 runs before the coil burns out and needs replacing. The terminal block can get very corroded in time so I occasionally disconnect the coil and the supply wires and clean out the inside with a small needle file. If the combustion is too fierce reduce the oxygen flow and/or the sample size as you suggested.
     
    Last edited: Nov 8, 2019