Crucible (Single) 3K-4-047

The crucible is used in the lid assembly to hold the sample (i.e. Benzoic Acid Tablet or Gelatin Capsule) in the CAL3K Vessel. Packaging: Crucibles are now packaged in quantities of 1 unit.

Compatibility: CAL3K-AP / CAL3K-A / CAL3K-F / CAL3K-S / CAL3K-ST

Life Span: The crucible lasts for 5-50 firings. The crucible should be replaced when necessary. The crucible in an oxygen bomb calorimeter contains the sample, which is a combustible material of 0.2 to 1.5g. The sample is ignited by a fuse which in turn is ignited by a firing wire. The firing wire is heated by an electrical current. An oxygen bomb calorimeter is used to measure the combustible (thermal) energy of a substance. The crucible is made out of stainless steel with a melting point of -1500 degrees Celsius. With prolonged use the crucible loses weight due to oxidation : it gets thinner. Eventually it disintegrates. If a crucible has disintegrated, the sample analysis must be discarded. The amount of sample determination depends on the burning temperature of the sample material and its corrosive properties. When a crucible disintegrates it does so by “dropping” the bottom, because the walls are thinner than the rest. The weight loss of the crucible is very visible before the sample is inserted, because the crucible is put onto a scale to be tared. For very high temperature determinations, a SILICA crucible is used. This is, however, normally avoided because of the high cost. Alternatively 3-10ml water can be added into the bomb. Part of the water is converted to steam and this helps to cool the stainless steel crucible. If water is used then the calibration of the bomb must be performed with water as well. The water in the vessel can be titrated after the burning process.