Atomic absorption spectrophotometer with improved drain trap interlock

摘要

The interlock assures that the end of a drain trap entrance pipe is covered with liquid. The system includes a control circuit with a circuit element which changes impedance with temperature changes. The circuit element is arranged to be thermally coupled with the drain trap liquid when the discharge end of the drain trap entrance pipe is immersed in the liquid. The circuit applies a current to the circuit element to thereby apply energy thereto. The circuit element achieves a lower steady-state temperature when thermally coupled with the liquid. The control circuit is operable to detect the difference in resistance when the circuit element is at the lower temperature. The control circuit is connected to a valve device for controlling combustion gas for the spectrophotometer and is operable to enable the valve device to enable the spectrophotometer when the circuit element is at the lower temperature and to disable the spectrophotometer at a higher temperature.