do_measurementprinciple
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do_measurementprinciple [31/03/2015 13:33] pieter [Temperature effects on the probe output] |
do_measurementprinciple [31/03/2015 13:34] pieter [Temperature effects on the probe output] |
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| There are two factors related to temperature which must be recognised in order to correlate the output of the dissolved oxygen probe with concentration of molecular oxygen in the sample. | There are two factors related to temperature which must be recognised in order to correlate the output of the dissolved oxygen probe with concentration of molecular oxygen in the sample. | ||
| - | * As the temperature of water decreases, kinetic energy of water and oxygen molecules decreases and molecular attraction increases. As a result, the concentration of oxygen which must be present in the water to establish a particular concentration of oxygen at the water-to-Teflon interface increases.// | + | * As the temperature of water decreases, kinetic energy of water and oxygen molecules decreases and molecular attraction increases. As a result, the concentration of oxygen which must be present in the water to establish a particular concentration of oxygen at the water-to-Teflon interface increases. |
| - | * The resistance to oxygen diffusion through the Teflon membrane increases as temperature decreases.// | + | * The resistance to oxygen diffusion through the Teflon membrane increases as temperature decreases. |
| Both of the temperature factors serve to decrease the rate at which oxygen molecules reach the surface of the cathode as temperature decreases. Therefore, if the read-out from the dissolved oxygen meter is to display the correct reading of oxygen concentration for all samples which have the same concentration of oxygen but are at different temperatures, | Both of the temperature factors serve to decrease the rate at which oxygen molecules reach the surface of the cathode as temperature decreases. Therefore, if the read-out from the dissolved oxygen meter is to display the correct reading of oxygen concentration for all samples which have the same concentration of oxygen but are at different temperatures, | ||
do_measurementprinciple.txt · Last modified: 31/03/2015 13:35 by pieter
