Emerson 3000 World Class, Instruction Bulletin, d.Cell - General, A-3INNER PROBE ASSEMBLY

Instruction Bulletin

Appendix A Rev. 3.9 May 2005

World Class 3000

d.Cell - General

The components which make up the cell are machined to close tolerances and assembled with care to provide accurate oxygen measurements. Any replacement requires attention to detail and care in assembly to provide good results.

Failure to follow the instructions in this manual could cause danger to personnel and equipment. Read and follow instructions in this manual carefully.

The oxygen probe includes an inner electrode for the cell assembly. It consists of a platinum pad and a platinum/inconel composite wire which produces the cell constant offset voltage described in the Nernst equation.

With this pad and wire, the constant will be between -10 and +15 mV. The cell constant is noted in the calibration data sheet supplied with each probe.

Every probe should be calibrated and checked after repair or replacement of cell, pad and wire, heater, and thermocouple, or after disassembly of the probe.

A-3 INNER PROBE ASSEMBLY

The inner probe assembly, Figure A-5, consists of six main parts:

b.A heater that is helically wrapped on a quartz support cylinder and insulated.

c.A chromel-alumel thermocouple which acts as the sensing element for the temperature controller. (Not visible in Figure A-5; located within ceramic support rod.)

d.A platinum screen pad which forms electrical contact with the inner electrode of the electrochemical cell. (Not visible in Figure A-5; located at end of ceramic support rod.) The pad is attached to an inconel wire which carries the signal to the terminal strip.

e.A V-strut assembly to give support to the inner probe assembly.

f.A tube to carry reference air to the cell.

Turn to Service and Normal Maintenance, for repair procedures for probe components.

HEATER

	INSULATING
	GASKET	REFERENCE
V-STRUT		AIR TUBE

CERAMIC

SUPPORT

ROD

a.Ceramic support rod with four holes running through the length. The holes serve as insulated paths for the cell signal wire and thermocouple wires.

27270015

Figure A-5. Inner Probe Assembly

A-4 Appendices Rosemount Analytical Inc. A Division of Emerson Process Management