Emerson 3000 Probe Junction BOX, Cable Assembly, Probe Options, Abrasive Shield Assembly

World Class 3000

Instruction Bulletin

Appendix A Rev. 3.9 May 2005

PROBE

JUNCTION BOX

TERMINALCOVER STRIP

During calibration, two gases of different known oxygen concentrations are injected one at a time through the calibration gas fitting. Stainless steel tubing delivers this gas to the process side of the cell. In a healthy cell, the difference in oxygen pressure from the process side to the reference side of the cell will cause a millivolt output proportional to the difference in oxygen levels. The electronics unit can use the two millivolt outputs caused by the two calibration gases for either automatic or semi-automatic calibration.

CALIBRATION

GAS FITTING

REFERENCE

AIR FITTING

27270016

Figure A-6. Probe Junction Box

A-4 PROBE JUNCTION BOX

The probe junction box, Figure A-6, is positioned at the external end of the probe and contains a terminal strip for electrical connections and fittings for reference air and calibration gases. Fittings are for 0.250 inch stainless steel tubing on American units and

6 mm on European units. The calibration fitting has a seal cap which must remain in place except during calibration. A tubing fitting is also supplied to be used with the calibration gas supply during calibration.

If the calibration gas bottles will be permanently hooked up to the probe, a manual block valve is required at the probe (between the calibration fitting and the gas line) to prevent condensation of flue gas down the calibration gas line.

During operation and calibration, reference air is supplied through the reference air fitting to the reference side of the cell. This gives the system a known quantity of oxygen with which to compare the oxygen level in the process gas. Though ambient air can be used for this purpose, accuracy can only be assured if a reference air set is used.

Do not attempt to remove a process gas sample through either gas fitting. Hot gases from the process would damage gas hoses in the probe junction box.

A-5 CABLE ASSEMBLY

The system uses a 7-conductor cable to connect the probe to the electronics package. Standard length for this cable is 20 feet (6 m), but lengths up to 150 feet (45 m) are available. The seven conductors include one shielded pair of wires for the cell millivolt signal, one shielded pair of type K wires for the thermocouple, and three individual 16-gauge wires for the heater and for ground. The assembled conductors are wrapped by a type K TeflonTM jacket and braided stainless steel shield. The TeflonTM and stainless steel jacketing is suitable for high temperature use. All metal shields are isolated at the probe end and connect by drain wires to ground at the electronics.

A-6 PROBE OPTIONS

a.Abrasive Shield Assembly

The abrasive shield assembly, Figure A-7, is a stainless-steel tube that surrounds the probe assembly. The shield protects the probe against particle abrasion and corrosive condensations, provides a guide for ease of insertion, and acts as a probe position support, especially for longer length probes. The abrasive shield assembly uses a modified diffusor and vee deflector assembly, fitted with dual dust seal packing.

Rosemount Analytical Inc. A Division of Emerson Process Management Appendices A-5