Automatic gas sensor calibration system
AssigneeRel-Tek
InventorsAlbert E. Ketler, Bradley H. Baker, Thayananthan Narayanan, Lauren E. Sargent, Ronald C. Smathers, Ehren R. Graber
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Abstract
An automatic system for calibrating gas sensors comprising a source of SPAN gas and a source of ZERO gas, and a means to control the flow of these gases to sensors. The system schedules and makes all required sensor value corrections and adjustments without human intervention. High resolution monitoring enables life extensions for the sensors, as well as higher accuracy monitoring than would be reasonably expected from low cost sensors.
Claims25
A process for automatically calibrating gas sensors comprising:
- a. connecting a calibrating gas tube to each sensor;
- b. introducing SPAN or ZERO gas into a sensor calibration tube manifold;
- c. waiting a predetermined time for the SPAN or ZERO gas to travel to each sensor and/or for the sensors to register the SPAN gas in a stable fashion;
- d. detecting the raw digital value transmitted for each sensor and assigning calibrated values to the proper sensor configuration registers;
- e. terminating the flow of SPAN or ZERO gas;
- f. introducing ZERO or SPAN gas into the sensor calibration tube manifold wherein both ZERO gas and SPAN gas are used;
- g. waiting a predetermined time for the ZERO or SPAN gas to travel to each sensor and/or for the sensors to register the ZERO or SPAN gas in a stable fashion;
- h. assigning calibrated values to the sensor registers;
- and
- i. turning off the ZERO or SPAN gas flow.
Apparatus for automatically calibrating gas sensors comprising:
- a. a calibration gas tube connected to each sensor;
- b. a source of SPAN gas and a source of ZERO gas;
- c. a computer to control introduction and termination of SPAN gas and ZERO gas to each sensor, wherein said computer directs performance of automatic gas calibration on a scheduled basis.
The apparatus according to claim 23 further comprising at least one slave card connected to the master card, said at least one slave card containing up to four 4-20 ma (or other) raw signal inputs and with corresponding 4-20 ma (or other) calibrated signal outputs.
Dependencies are inferred from the claim text.