ENOTEC OXITEC 5000 Oxygen Analyzer Maintenance Guide

ENOTEC OXITEC 5000 Oxygen Analyzer Maintenance Guide

OXITEC 5000/5000+is a direct insertion flue gas oxygen analysis system used for combustion equipment, flue gas, and inert gas mixing processes. The system consists of SME-5 electronic units and KES series direct insertion probes, with zirconia sensors as the core measuring component. The probe is installed on the flue or combustion chamber, and the electronic unit is responsible for power supply, signal processing, gas path control, and human-machine interaction. For industrial sites that operate continuously for a long time, correct installation, regular calibration, and targeted maintenance are key to ensuring stable oxygen content data, reducing fuel costs, and minimizing downtime.

Measurement principle and system composition

The OXITEC 5000 series adopts the principle of zirconia oxygen measurement. The oxygen sensor at the tip of the probe is heated to about 800 ° C, and the reference side uses air with a known oxygen concentration, typically 20.95% O ₂; Measure the side contact process flue gas. When the oxygen partial pressure on both sides is different, the sensor generates a millivolt signal, which is logarithmic to the oxygen partial pressure ratio on both sides. The electronic unit converts the mV signal into the oxygen concentration in the flue gas based on the Nernst equation. The airtight isolation between reference air and process gas is extremely important. If the seal fails, the measured value will drift significantly.

The system typically includes electronic units, direct insertion measuring probes, pneumatic cables, probe signal cables, optional solenoid valves, flanges, and isolation components. The protection level of the electronic unit can reach IP66, and the probe is IP65. The ambient temperature of electronic units is generally -20 ° C to+55 ° C, and the probe junction box can adapt to -40 ° C to+80 ° C. Standard probes are suitable for smoke up to 600 ° C; When equipped with a cooling protection tube, it can cover higher temperature conditions. If the flue gas contains combustible components such as CO and H ₂, they may react with oxygen on the sensor surface, resulting in low measurement values. Therefore, it is necessary to evaluate the process conditions and, if necessary, choose protection schemes such as CSP.

Safety and on-site inspection before installation

The system is powered by line voltage, and the power must be cut off before removing the terminal cover. Only trained and authorized personnel are allowed to carry out electrical installation, commissioning, and maintenance. The installation location should avoid the accumulation of flammable gases, as the working temperature of the sensor can reach up to 800 ° C, posing a risk of ignition. The surface temperature of the probe during operation can reach 150 ° C to 800 ° C. When disassembling, it is necessary to wear insulated gloves and turn off the power supply of the electronic unit first. The probe should be stored after cooling to below 35 ° C.

Before installation, it should be checked whether the system numbers of the probe and electronic unit are consistent; Is the voltage on the nameplate consistent with the on-site power supply; Whether the electrical wiring is correct; Is the gas path connection sealed; Whether the flange is welded airtight, whether the bolts are tightened, and whether the gaskets are intact; Whether the on-site conditions match the technical data. The electronic unit should be installed at a height that is easy to observe, with sufficient space left around: at least 200 mm above and below, and at least 50 mm left and right. Avoid vibration greater than 2g and maintain IP protection level.

Electrical wiring and cable requirements

The maximum length of the probe signal cable FEP-0001 can reach 150 m, and the minimum bending radius is 96 mm. The temperature range during installation is -5 ° C to+50 ° C, and the operating temperature range is -40 ° C to+90 ° C. The signal cable should intersect with the power cable at a right angle to avoid interference caused by parallel wiring. The cable shielding layer can only be connected at the PE terminal of the electronic unit and cannot be grounded at the probe end at the same time.

The functions of each wire of the probe cable are clear: the O ₂ sensor uses white/brown and brown; Thermocouples use green and white; Probe heating uses black, blue, green/yellow; The solenoid valve uses gray and gray blue. The electronic unit terminals include power supply L/N/PE, O ₂ sensor signals, thermocouple signals, analog output 4-20 mA, relay contacts, probe solenoid valves, measurement range switching, calibration release, and process pressure input. The analog output is active 4-20 mA, with a maximum load of 500 Ω. Relay contacts are typically 24 V AC/DC, 1 A; The probe solenoid valve contacts can withstand up to 230 V AC/DC, 1 A.

The internal fuse of the electronic unit needs to be replaced according to the specifications. Common specifications include: F3 and F4 are 0.5 A; F5 is 1.0 A; F12 is 2.0 A; F1 and F2 are 4.0 A. Before replacing the fuse, the power must be turned off and the voltage, current, and characteristics of the new fuse must be confirmed to be consistent.