Teledyne F = kSO2, M102E/M501 TRS, kSO2 * ⎯⎯F⎯→ SO2 + hv330nm, Theory Of Operation, Equation

M102E/M501 TRS THEORY OF OPERATION

(Addendum to M101E Manual - P/N 04740 Rev A)

The amount of detectable UV given off by the decay of the SO2* is affected by the rate at which this reaction occurs (k).

F = k(SO2 *)

Where:

F	=
k	=
SO2*	=

So:

(Equation 9-5)

the amount of fluorescent light given off. The rate at which the SO2* decays into SO2. Amount of excited SO2 in the sample chamber.

k(SO2 *) ⎯⎯F⎯→ SO2 + hv330nm

(Equation9-6)

Finally, the function (k) is affected by the temperature of the gas. The warmer the gas, the faster the individual molecules decay back into their ground state and the more photons of UV light are given off per unit of time.

In summary, given that the absorption rate of SO2 (a) is constant, the amount of fluorescence (F) is a result of:

•The amount of exited SO2* created which is affected by the variable factors from equation 10-2 above: concentration of SO2; intensity of UV light (I0); path length of the UV light (x) and;

•The amount of fluorescent light created which is affected by the variable factors from

equation 10-5: the amount of SO2* present and the rate of decay (k) which changes based on the temperature of the gas.

So, when the intensity of the light (I0) is known; path length of excited light is short (x).; the temperature of the gas is known and compensated for so that the rate of SO2*decay is constant(k). and; no interfering conditions are present (such as interfering gases or stray light); the amount of fluorescent light emitted (F) is directly related to the concentration of the SO2 in the Sample Chamber.

The Model 100 E UV Fluorescence SO2 Analyzer is specifically designed to create these circumstances.

•The light path is very short (x).

•A reference detector measures the intensity of the available excitation UV light and is used to remove effects of lamp drift(I0).

•The temperature of the sample gas is measured and controlled via heaters attached to the sample chamber so that the rate of decay (k) is constant.

•A special hydrocarbon scrubber removes the most common interfering gases from the sample gas.

•And finally, the design of the sample chamber reduces the effects of stray light via its optical geometry and spectral filtering.

The net result is that any variation in UV fluorescence can be directly attributed to changes in the concentration of SO2 in the sample gas.

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