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Corrosion Monitoring in a Self Maintenance System

IP.com Disclosure Number: IPCOM000088918D
Original Publication Date: 1977-Aug-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 2 page(s) / 33K

Publishing Venue

IBM

Related People

Chrisfield, RP: AUTHOR [+3]

Abstract

This arrangement enables a system to check the corrosion in its own cooling system. Thus, monitoring can be done on a regular basis without the need of human interaction.

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Corrosion Monitoring in a Self Maintenance System

This arrangement enables a system to check the corrosion in its own cooling system. Thus, monitoring can be done on a regular basis without the need of human interaction.

The corrosion probe includes four resistors arranged in a bridge 11 configuration. Two ultra-precision resistors R1 and R2 form the top half of the bridge. The remainder of the bridge consists of a brass element, half of which is exposed to the water and is represented by a resistance Rt. The other half of the brass element is coated with a plastic so that no corrosion can take place on this half. This coated half is represented by resistance Rr in the bridge. The bridge 11 is excited with a 1 kilocycle triangle wave generated by a 1 kilocycle oscillator 10 located on a circuit card within the system. This AC signal across the bridge allows AC coupling in the amplifiers 12 and 14 so that any DC offsets that appear will not affect the operation of the circuit.

The voltage across the bridge is a triangle or sawtooth wave equal to the excitation voltage times some function of the resistors R1, R2, Rr and Rt. As the exposed element Rt corrodes, its cross-sectional area decreases, causing the resistance to increase. Thus, the voltage across Rt increases, and the differential voltage across the bridge increases.

The output across the bridge 11 is amplified by the probe amplifier 12 which is located in the probe. This input to the amplifier is a differential input, and the output therefrom is also a differential output. The amplified differential signal is sent from the probe to the corrosion card via a shielded twisted pair for noise immu...