Sensor Operations - Ametek Dycor CG1100 Series User Manual

Sensor Operations

The sensing element itself is a closed-end tube or disk of
ceramic zirconium oxide stabilized with an oxide of yttrium or
calcium. Porous platinum coatings on the inside and outside
serve as a catalyst and as electrodes. At high temperatures
(generally above 1200°F / 650°c), oxygen molecules coming
in contact with the platinum electrodes near the sensor be-
come ionic. As long as the oxygen partial pressure on either
side of the cell is equal, the movement is random and no net
flow of ions occurs. If, however, gases having different oxygen
partial pressure are on either side of the cell, a potentiometric
voltage is produced (Figure 1-1). The magnitude of this voltage
is a function of the ratio of the two oxygen partial pressures. if
the oxygen partial pressure of one gas is known, the voltage
produced by the cell indicates the oxygen content of the other
gas. A reference gas, usually air (20.9% o
the gases.
Figure 1-1. Zirconium oxide cell principle of operation.
1-2 | Dycor CG1100 Oxygen Analyzer
Disconnect AC power from the analyzer before performing any main-
tenance or troubleshooting.
The furnace and furnace insulation cover are hot during normal opera-
tion (up to 500 °F, 260 °C inside the furnace insulation cover). Allow
analyzer components to cool for at least an hour before working inside
the analyzer. Use caution and wear appropriate gloves when handling
components or when touching analyzer components near the furnace!
Basic Elements of the Sensor
The CG1000-RTP analyzer consists of the following basic systems:
• Flow control valve, all inlet and outlet tubing, sensing cell
Plumbing:
and the sensing cell fitting.
•
Measuring System:
and the control unit.
•
Temperature System:
mocouple (monitors furnace operating temperature), and the sensor
board containing cold junction thermocouple compensation, intercon-
nect wiring and the control unit. The temperature system keeps the
sensing cell at a constant temperature.
The Oxygen Measuring Cell
Sensing cell, sensor board, interconnecting wiring
Electrical cell heater (furnace), the type "K" ther-
), is used for one of
2