WO1994001757A1

WO1994001757A1 - Corrosion profiling and diagnostic system

Info

Publication number: WO1994001757A1
Application number: PCT/US1993/006201
Authority: WO
Inventors: Michael W. Osborne; David W. Hughes
Original assignee: Purafil Inc
Current assignee: Purafil Inc
Priority date: 1992-07-02
Filing date: 1993-06-25
Publication date: 1994-01-20
Anticipated expiration: 1995-01-02
Also published as: AU4657193A

Abstract

The corrosion profiling and monitoring system (25) comprises a metallic corrosion detector (28) and at least one other metallic corrosion detector (29) for sensing levels of corrosion at different locations and generating an uncorrected signal from each corrosion detector (28 and 29), calibration and correction algorithms (30 and 31) for converting the uncorrected signal from each of the metallic corrosion detectors to a corrected signal representing true corrosion, a comparison step (32) for comparing the amount of measured corrosion from each of the corrosion detectors, and a data logger (34) for storing the compared values of the amounts of measured corrosion. Such information is indicative of the spatial fitness profile of a system subject to deterioration induced by its environment.

Description

CORROSION PROFILING AND DIAGNOSTIC SYSTEM

FIELD OF THE INVENTION

The present invention relates in general to a system for monitoring deterioration of an environment. More particularly, the invention relates to comparing and monitoring corrosion and deterioration in different locations about its environment so as to obtain a spatial fitness profile of the system.

BACKGROUND OF THE INVENTION Certain components and devices, such as metal- containing components in electronic systems, and filters within gas purification systems are highly sensitive and subject to atmospheric corrosivity. Prolonged exposure to such atmospheric corrosivity has harmful effects on the electrical components and the gas filtration media and can cause deterioration and failure of the systems over time.

Corrosion can take several forms. One form of corrosion occurs in the formation of metal oxides resulting from a reaction between the metallic components and devices of the system with oxygen in the air. Another form of corrosion occurs, for example, when an electronic system is subject to corrosive gases which are harmful to the circuitry within the system. Such gases include sulfur dioxide, hydrogen sulfide, hydrogen chloride, and the like. Even at parts-per-million concentrations, the presence of these gases can lead to failure of the electronic equipment due to corrosion of circuitry or deterioration of the filtration medium due to corrosive gases, in as little time as several months, depending on the concentration of the corrosive agents.

Because of the potential of costly downtime from electronic failures and because of safety factors, industries are becoming more concerned with measuring, monitoring and regulating the environment in which such electronic systems reside. One such preventative measure is the use of a gas or chemical purification system placed in the room or housing, whereby the filtration medium of the system filters or purifies the environment of atmospheric impurities so that corrosive gases and particles are less likely to reach the circuitry within the electronic systems. A problem in relying upon the filtration medium of a purification system to purify the environment is that presently no means of monitoring the filtration medium is available in real-time. Thus, the deterioration of the filtration medium often goes unnoticed, thereby allowing corrosive agents to be present in the atmosphere and to corrode the electrical components within electronic systems. Historically, the standard industry method for measuring corrosivity of the environment in a room is commonly referred to as the "coupon" method, whereby a clean copper strip is exposed to the atmosphere for a period of time. Under this method, the amount of corrosion on the strip can be determined by electrochemically converting the oxidized copper back to metallic copper. By measuring the amount of electrical charge needed for the above conversion, the amount of copper that corroded in the time period of exposure can be calculated. To reflect the amount of corrosion experienced by the room, an accepted standard set by the Instrument Society of America (ISA) can be applied to describe the weekly, monthly, or annual build-up of corrosion on similar substrates contained in the same environment.

A major disadvantage of the coupon method is that it is labor intensive and requires costly analysis and measurement of the corroded strip which can be performed only after the exposure period, which, for example, can be between one and three months. Another disadvantage in the present method is that once the strip of copper is corroded and measured for collective corrosion, the used metal strip must be discarded and a new metal strip must be exposed in the environment so that further actual corrosion measurements can be taken. Thus, each strip yields information only on the average amount of corrosion suffered by the test strip. It is, therefore, difficult to determine the rate at which corrosion occurs if the corrosion rate varies at variable time intervals.

A further disadvantage of the present method is that by using the copper strip, only the corrosivity of the atmosphere can be measured. Such corrosivity levels measured by the copper strip may not fully describe other hazards in the environment, such as relative humidity, temperature, physical shock and the like.

Recent products and patents have attempted to address these problems and disadvantages. One of such systems is disclosed in U.S. Patent No. 4,869,874 of Falat whereby an atmospheric monitoring device senses atmospheric conditions and generates input to a microprocessor. The microprocessor scans the signals generated and records in a memory module excursions from set conditions which lasts for more than a designated period of time. The device includes sensors for temperature, relative humidity, pressure and corrosion indicators. However, in order to achieve accurate, useful results, Falat requires that the monitoring period occur over an extended designated period of time, usually on the order of six months. Thus, a need exists for a deterioration monitoring system which is able to sense corrosion as well as various atmospheric conditions and is able to generate accurate, useful data on a more continuous, real-time basis. Another method developed to address the problems encountered by using the coupon method to monitor corrosion is the use of a quartz crystal oscillator, whereby when mass is added to the crystal, measurements of the change in the frequency of the quartz crystal can be obtained. This method is disclosed in U.S. Patent No. 3,253,219 of Littler. Littler discloses the use of a piezoelectric crystal which is capable of being excited to a resonance vibration by an alternating electric field of the proper frequency. It is known that the resonance frequency of a piezoelectric crystal can be modified by affixing a mass of material to one or both sides of the crystal, and the oscillation frequency decreases as more mass is attached to the element. For example, Littler discloses that when a crystal with a 3.5 MHz oscillating frequency is utilized, an increase in thickness of 1 A is said to be equivalent to a decrease in frequency of 1 Hz.

Littler, however, does not address the corrosion of metals, and does not report corrosion measurements in terms relative to an accepted industry standard, such as the Instrument Society of America (ISA) . Furthermore, Littler does not address the need for sensing other factors such as relative humidity, temperature, electric field, magnetic field, particulates or physical shock.

An electronic corrosion sensor identified by the trademark ONGUARD™ has been marketed by Purafil, Inc. and incorporates piezoelectric technology, whereby a piezoelectric crystal is used to monitor levels of corrosion in a room. Additionally, the ONGUARD unit reports levels of corrosion in terms recognized by industry standards, and includes sensors which are sensitive to temperature and relative humidity. The ONGUARD unit monitors corrosion on a real-time, continuous basis and calculates cumulative and incremental corrosion rates, as well as projects corrosion levels up to thirty days in advance so as to predict when failures might occur. All of the above-mentioned patents and products involve methods and apparatus for sensing corrosion in a room, such as in a computer control room. None of the above-mentioned systems, however, disclose a system which compares levels of corrosion at different locations about an electronic system or a computer room so as to obtain a fitness profile of the electronic system or the computer room. Accordingly, a need exists for an apparatus which can include a multiplicity of corrosion detectors, whereby the detectors sense environmental conditions via a plurality of test specimen/ and the apparatus compares data from each of the sensors to provide a spatial corrosion profile indicating different rates of corrosion build-up at different locations. Thus, a more accurate indication of the corrosion deterioration of the components within an electronic system, or the deterioration of a purification medium of a gas purification system, can be obtained for further evaluation by the user. It is to the provision of such a corrosion profiling system that the present invention is primarily directed. Additionally, none of the above-mentioned patents or products disclose a system for monitoring and comparing deterioration and other environmental factors about different locations of a room so that the most efficient placement of the electronic systems within the room can be planned and implemented. For example, if the compared corrosion level at one location is higher than the compared corrosion level at another location, then the more durable electronic system should be placed in the location with the higher potential for corrosion and a more sensitive electronic system should be placed in the location having the lower corrosion potential. Accordingly, there exists a continuing and heretofore unaddressed need for a corrosion profiling system which is capable of detecting and comparing corrosion levels so as to obtain a spatial fitness profile.

SUMMARY OF THE INVENTION

Briefly described, the present invention comprises a corrosion profiling apparatus and method for monitoring and comparing corrosion levels and other environmental conditions about different locations. Normally, the corrosion profiling system is positioned in a path of gas flow of a system subject to deterioration induced by its environment. The present invention comprises at least a first and a second metallic test specimen spaced from each other in different locations about the system, detector means for measuring the amount of corrosion on at least two of the metallic test specimen, means for comparing the amount of measured corrosion of one of the measured test specimen relative to another of the measured test specimen, and a data logging means for recording the compared measured corrosion. Thus, the corrosion experienced by each of the measured test specimen is indicative of the spatial fitness profile of the system.

The metallic test specimen of the metallic corrosion detector can take the form of one or a combination of several embodiments. One embodiment of the *. test specimen is a crystal, such as a piezoelectric crystal which has a constant natural oscillation frequency dependent upon the mass of the coating on its surface. Such a coating on the surface of the piezoelectric crystal can comprise a corrodible metallic substance, such as copper, gold, nickel, silver, zinc, and the like. When the corrodible metallic coating interacts or reacts with the atmosphere of its environment, the mass on the piezoelectric crystal surface will become altered, thus, altering the oscillation frequency of the crystal. Depending on the type of metallic substance the crystal is coated with and the type of environment the crystal is exposed to, the mass on the crystal will either increase or decrease. For example, an increase in the mass on the surface of the crystal will cause a decrease in the piezoelectric crystal natural oscillation frequency. Likewise, a decrease in the mass on the surface of the crystal will cause an increase in the crystal natural oscillation frequency. The corrosion profiling apparatus of the present invention comprises at least two test specimen, such as two piezoelectric crystals coated with metallic substances. Measurements of the amount of corrosion experienced by the piezoelectric crystals can be real-time, on-line and continuous measurements which are registered and can be converted to a value. Accordingly, the values for each of the test specimen can reflect a calibration and a correction step which accounts for any deviation in atmospheric conditions or in the apparatus during each interval of time. The corrected values of each of the test specimen can then be compared to each other so as to determine the differences in corrosion levels on each of the test specimen. A signal, generated by the comparison step can then indicate the spatial fitness profile of the system being tested. Alternatively, the corrected value can first be memorized in a data-logger, and then a comparison step can be used to compare the data extracted from the data-logger. The signal formed by each of the above-mentioned methods, can have the option of being stored or being displayed to the user.

The present invention can embody a small, stealthy unit, whereby the apparatus might be concealed from the sight of the user. Such an apparatus can be located within a system, such as directly on a printed wiring board of a computer, or concealed within a gas purification system, both upstream and downstream of the filtration medium. Additionally, the unit can be normally dormant, whereby the apparatus is capable of turning itself on at certain intervals so as to measure the amount of corrosion experienced by the test specimen. The present invention also can include a variety of sensors, including sensors for measuring temperature and relative humidity. Additionally, other sensors can measure magnetic field strength, electric field strength, and particulates in the atmosphere. Signals from these sensors can be displayed or can be directed to other devices such as a digital memory and can be used to trigger alarms to the user. The output display also can show levels of corrosion in incremental corrosion rate in values which can be related to ISA standards or other industry-accepted standards. Thus, the output from the present invention is capable of diagnosing the corrosive areas of a system subject to deterioration and is able to obtain a spatial fitness profile of the system for use in predicting and projecting the ultimate reliability of the device, component or system.

In other embodiments of the test specimen of the present invention, the step of measuring the amount of corrosion on at least one of the upstream and one of the downstream test specimen comprises measuring the light reflected from a metallic material or measuring an electrical resistance across a metallic material. These embodiments do not require the use of a piezoelectric crystal.

The corrosion profiling system of the present invention has many practical applications which address the need for monitoring and comparing corrosion deterioration and other factors about different locations. One exemplary application is the installation of the present invention at the input and the output of a gas filtration medium of a gas purification system. When the system is first installed, the corrosion from the input sensor should measure higher than the corrosion levels sensed by the output sensor, because the gas flow is being scrubbed or cleaned by the filtration medium of the purification system. As the filtration medium becomes exhausted, the filtration medium is less efficient in reducing the amount of corrosive agents in the gas stream. Thus, after some period of time, the corrosion level at the input equals the corrosion level at the output indicating that the filtration media is used up. The present invention, therefore, enables a user to determine when the filtration medium needs replacement so that ^■ the medium can be immediately replaced to avoid damage to systems caused by the presence of corrosive agents in the environment.

Additionally, another application of the present invention is the use of multiple sensors within a circuit board of a computer system for monitoring and comparing deterioration about the spatially positioned sensors. This type of information can be used to determine the locations within the electronic system that are most susceptible to corrosion deterioration.

It is, therefore, an object of the present invention to provide a corrosion profiling system for monitoring and comparing deterioration and other environmental factors about different locations so that a spatial profile of the system can be obtained.

Another object of the present invention is to provide a corrosion profiling system which is small, stealthy, and tamper resistant.

A further object of the present invention is to provide a corrosion profiling system which monitors and compares deterioration and corrosion, with the monitor including a variety of sensors, such as sensors for temperature, corrosion, relative humidity, magnetic field strength, electric field strength, and particulates. It is another object of the present invention to provide a corrosion profiling system for use in a gas or an air purification system so as to monitor the effectiveness of the gas or air filtration medium.

Another object of the present invention is to provide a corrosion profiling system having the option of detecting specie-specific or gas-specific types of corrosion in the environment.

A further object of the present invention is to provide a corrosion profiling system which can be used within an electronic system for profiling corrosion via multiple detectors which have been spatially arranged.

A more complete understanding of the present invention will be had by those skilled in the art, as well as an appreciation of additional advantages, which will become apparent upon reading the detailed description of the preferred embodiment and examining the drawings, the following of which is a brief description.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a side elevational view of one embodiment of the metallic test specimen of the present invention. Fig. 2 is a side view of another embodiment of the metallic test specimen of the present invention.

Fig. 3 is a side view of yet another embodiment of the test specimen of the present invention.

Fig. 4 is a schematic diagram illustrating the process used to indicate the spatial fitness profile of a system using any of the above-mentioned metallic corrosion test specimen.

Fig. 5 is a schematic diagram illustrating another process of indicating the spatial fitness profile of a system using any of the above-mentioned metallic test specimen.

Fig. 6 is a schematic diagram illustrating another embodiment of the corrosion profiling system including a magnetic field strength sensor, an electric field strength sensor, and a particulate sensor. Fig. 7 is a schematic diagram illustrating an interval timer implemented in any of the corrosion detector embodiments of the present invention.

Fig. 8 is a bar graph illustrating the interval timing concept of Fig. 6.

Fig. 9 is a side view illustrating one application of the present invention.

Fig. 10 is a line graph illustrating an example output of incremental corrosion rate from the input sensor and the output sensor of Fig. 9.

Fig. 11 is another line graph showing another example of the incremental corrosion rate from the input sensor and from the output sensor of Fig. 9.

Fig. 12 is a perspective view illustrating another application of the present invention within an electronic system.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring now in greater detail to the drawings in which like numerals indicate like parts throughout the several views, Figs. 1, 2 and 3 illustrate several embodiments of metallic test specimen used to detect levels of corrosion in metallic corrosion detectors, such as the corrosion detectors 28, 29, 38, 39, and 48 as shown in Figs. 4 through 6, respectively. As illustrated in Fig. 1, one embodiment 10 of the metallic test specimen of the metallic corrosion detector comprises a quartz crystal, such as a piezoelectric crystal 11 having one side 12 and another side 14. Bonded to or deposited on each of the sides 12 and 14 of the piezoelectric crystal is a layer of chromium 15 which is approximately 30 A thick. A layer of corrodable metallic substance 16 is then bonded or deposited onto the layer of chromium 15. The layer of chromium 15 serves to bond the corrodable metallic substance 16 to the piezoelectric crystal 11. Longitudinal leads 17 are placed over both sides of the metallic substance 16 so as to connect the metal-coated crystal with other elements of the metallic corrosion detector, such as a power source, an oscillator, an amplifier and a counter (not shown) in Fig. 1 which are all well known in the art of quartz crystal monitoring techniques. Thus, the piezoelectric crystal 11 can be implemented for use as any or all of the test specimen of the spaced metallic corrosion detectors required to obtain an accurate spatial corrosion profile. Fig. 2 shows another embodiment 18 of the metallic test specimen used to detect corrosion levels of the corrosion detectors 28, 29, 38, 39 and 48 as shown in Figs. 4 through 6, comprising a metallic strip 19 of material, such as copper. A clean metallic strip 19 is usually assumed to carry an initial copper oxide corrosion thickness of approximately 100 A. By exposing at least two spatially positioned metallic strips to the atmosphere for a period of time, ranging from one to three months, the change in thickness of corrosion build-up on the strip 19 occurs, and the thickness of corrosion is measured. Such measurements require the use of a complex coulometric reduction procedure, well known to those skilled in the art. Alternatively, elements within the circuit of the metallic corrosion detector also can measure the intensity of incident light 20 projected onto the metallic strip 19 with respect to the intensity of the light reflected 21 from the metallic strip. Changes in the intensity and other properties of the reflected light with respect to the incident light are related to the amount of corrosion suffered by the metallic strip 19.

Another embodiment 22 of the test specimen of the metallic corrosion detector in Figs. 4 through 6 comprises a metallic strip 23 of material (Fig. 3) such as copper, iron, steel, zinc, nickel or silver which would each find use in corrosive environments. After one or more of the metallic strips 23 have been exposed to the atmosphere for a period of time, corrosion of the strip occurs which alters the electrical resistance of the strip and the changes in resistance across the metallic strip 23 can be measured by ohm meter 24. Such changes in electrical resistance occur as corrosion levels increase in time and are, in part, due to a reduction of the effective cross- sectional area of the metallic strip 23.

All of the above-mentioned test specimen embodiments 10, 18 and 22 can be coated with or comprised of metallic substances, such as gold, copper, iron, steel, zinc, nickel or silver. The test specimen used in each of the corrosion detectors in the present invention also can be tailored so as to detect a specie-specific corrosive gas within the environment. For instance, the metal, zinc can only be corroded by the gas chlorine. Therefore, if zinc is used as the metallic test specimen in the detector and the zinc corrodes, then chlorine must have been present in the atmosphere. This type of knowledge helps the user to determine within the corrosion profiling system where the most corrosive gases occur and specifically, the type of gases present in the environment. Under these circumstances, the user might be able to diagnose the problem and to find the source of the corrosive gases.

Fig. 4 shows a schematic diagram of a corrosion profiling system 25, including a metallic corrosion detector 28 and another metallic corrosion detector 29, which are normally spaced and positioned in different locations, preferably at least one in a gas stream upstream and at least one in a gas stream downstream of the system being monitored and profiled. The metallic corrosion detectors 28 and 29 can comprise any of the metallic test specimen 10, 18, or 22 illustrated in Figs. 1 through 3, and other elements (not shown) such as a power source, an oscillator, and an amplifier, which are all well known in the art. Additionally, the system 25 can comprise a plurality of corrosion detectors, such as detectors 28 and 29, spatially arranged so as to determine the levels of corrosion in different locations and comparing the measured corrosion levels of the different locations. It would be desirable to obtain corrosion information from many different locations to determine an accurate fitness profile of the system or environment being monitored.

Each of the metallic corrosion detectors 28 and 29, sense corrosion levels in the environment and generate raw or uncorrected signals. The uncorrected signals from each of the detectors are then transmitted to calibration and correction algorithms, such as calibration and correction algorithm circuits which convert the raw, uncorrected signals to corrected signals which indicate true-corrosion. Furthermore, the calibration and correction algorithms 30 and 31 can also include conventional atmospheric sensors (not shown) , such as a relative humidity sensor and a temperature sensor. Such sensors can be of a conventional design, such as a National LM 35, which can be used as a temperature sensor, and a humidity sensor can comprise a MINICAP 2, manufactured by Panametrics. Moreover, the calibration and correction algorithms 30 and 31 preferably can be incorporated into a programmable microprocessor using techniques which are well known to those skilled in the art. Once the corrected signals or true-corrosion levels of each metallic corrosion detector 28 and 29 are determined, the values from each of the detector are transmitted to a comparison step 32 (Fig. 4) , whereby the values of true-corrosion from each of the metallic corrosion detectors 28 and 29 are compared to each other so as to determine the differences in corrosion levels experienced by each of the metallic corrosion detectors. Moreover, the differences in other environmental conditions, such as the temperature and relative humidity at each detector can be compared to reflect the relevances of temperature and relative humidity. The compared values of true-corrosion levels can then be stored in a data logger 34, which can embody a memory chip. The data logger can then store all the readings and comparisons performed by the comparison step 32 so as to notice any deviation in the corrosion levels experienced by the corrosion detectors, the temperature, or the relative humidity. An optional output is available to the user via any number of output means, which indicates the variances and differences in the levels of corrosion experienced by the spatially positioned detectors.

Fig. 5 illustrates a schematic diagram of another embodiment 35 of the corrosion profiling and diagnostic system, including a metallic corrosion detector 38 and a metallic corrosion detector 39. Similar to the embodiment of Fig. 4, one of the components of the metallic corrosion detectors 38 and 39 comprise metallic test specimen for measuring levels of corrosion, which can embody any of the metallic test specimen 10, 18 and 22 as shown in Figs. 1 through 3. Other elements of the metallic corrosion detectors 38 and 39, which are not shown in Fig. 5, include conventional elements, such as a power source, an oscillator, an amplifier, and a counter, which are all well known in the art. Thus, the metallic corrosion detectors 38 and 39 can develop uncorrected signals indicating levels of corrosion experienced by their respective corrosion detectors which enter circuits having a calibration and correction algorithm, such as the calibration and correction algorithms 40 and 41. Such algorithms convert the uncorrected signals to a corrected signal indicating true-corrosion. Furthermore, the calibration and correction algorithms 40 and 41 can take into effect other environmental conditions, such as temperature and relative humidity by sensors (not shown) , which sense the different atmospheric conditions. A data logger 42, as shown in Fig. 5, then stores the corrected signals generated by each of the calibration and correction algorithms 40 and 41. After the data is stored, a comparison step 44 can be incorporated to compare the values stored in the data logger, by means of a comparator which is generally well known in the art. The comparison step 44 compares variances and differences in the amount of corrosion level experienced by each of the metallic corrosion detectors 38 and 39. Similar to Fig. 4, an optional output means is available to indicate the measured and compared corrosion values to a user. The corrosion profiling and diagnostic system can combine the outputs of several types of sensors, as shown in the embodiment 45 (as illustrated in Fig. 6) , which is normally used within a housing 46 or a portable housing. This embodiment 45 includes a metallic corrosion detector 48, which can embody all or any of the metallic corrosion test specimen of Figs. 1 through 3 and other components (not shown) which are well known in the art. As shown in Fig. 6, an uncorrected signal is generated by the metallic corrosion detector 48 and is transmitted to a circuit having a calibration and correction algorithm 49. The calibration and correction algorithm can generate a signal indicating true-corrosion, and can reflect outputs from a relative humidity sensor 50 and a temperature sensor 51, which account for the effects of relative humidity and temperature on the corrosion level.

Once the corrected, true-corrosion signal is generated by the calibration and correction algorithm 49, the signal can enter a data logger 52, whereby a multiplicity of different sensors, such as a magnetic field strength sensor 54, an electric field strength sensor 55, and a particulate sensor 56 can be connected thereto. Such sensors indicate other important environmental factors which aid in the determination of true levels of corrosion, as well as other factors which contribute to corrosive build-up. A comparison step 53, comparing differences in levels of measured corrosion at various times can be performed by means of a comparator, which is well known in the electrical art. Such a comparator can, in addition, extract information from the data logger 52, as well as extract information from another data logger or another metallic corrosion detector (not shown) . Thus, corrosivity of the environment external of the housing 46 can be compared to corrosivity of the environment within the housing 46. It is understood that the metallic corrosion detector 48 can comprise a multiplicity of different detectors spatially positioned so as to obtain an accurate spatial profile of the atmosphere of the housing 46. Finally, an option of outputting the data is available. Therefore, data relating to corrosion levels experienced by each of the detectors is augmented with information, such as magnetic field strength information, electrical field strength information, and particulate information in order to obtain a more complete scenario of the spatial fitness profile of the environment.

It is understood that the comparison steps 32, 44, and 53 can also compare the corrected signals from each of the detectors to a standard, such as a standard determined by the Instrument Society of America (ISA) . Alternatively, a user-predetermined standard can be programmed into the comparator so that the user can determine the standard which the measured levels of corrosion from the detectors are being compared thereto.

The corrosion profiling and deterioration system of the present invention can be portably-powered, such as by a battery or a solar cell means. Additionally, measurements of the amount of corrosion experienced by the detector can be real-time, on-line, and continuous measurements. On the other hand, the system can be normally dormant, whereby the system is capable of turning itself on or activating itself at regular or preprogrammed intervals, or when certain atmospheric conditions are detected. For instance, by using an interval timer 55 to activate an "on-off" switch 56 (Fig. 7) , the switch can supply power 58 to the corrosion profiling and diagnostic system, such as the systems of 25, 35, and 45, and after an appropriate warm-up period the system makes a corrosion measurement. Thus, after performing such a measurement, the system is shut down and remains dormant until the next scheduled time interval.

Fig. 8 illustrates the graphical concept of interval timing, showing time reflected on a horizontal axis and measurement activity reflected on the vertical axis. During time period 60 when the unit is dormant, there is very little power consumed because the corrosion profiling system is dormant, and the only power required is that necessary in order to maintain the activity of the interval timer. The power consumption rises during measurement period 61 because the corrosion profiling system is active during these periods. These time intervals may be of arbitrary frequency and duration, and may be preset by the user. For example, measurements may be hourly, daily, weekly, monthly and so forth.

Many practical applications of the present invention which address the present needs of the industry are discussed hereinbelow. Fig. 9 illustrates one application of the present invention being incorporated and integral to a gas or a chemical purification system, whereby gas or chemical flows in the indicated direction, as shown by the arrows. At least one metallic corrosion detector 65 is positioned upstream of a filtration or purification medium 66, and at least one metallic corrosion detector 68 is placed downstream of the filtration medium 66. With measurements both upstream and downstream of the purification medium, the efficiency and effectiveness of the medium can be determined, as well as the rate at which the purification medium degrades. Thus, not only is the corrosion profiling system in this application used to determine the effectiveness and efficiency of the purification system, but the apparatus can be used to predict or project the probable lifetime of the purification medium so as to consistently time the replacement of the purification medium assuming that atmospheric conditions remain the same.

Figs. 10 and 11 show line graphical representations of the incremental corrosion rate, on the vertical axis, versus the time, on the horizontal axis. The input sensor line reflects readings from at least one metallic corrosion detector, such as detector 65, which is in the stream of gas flow of the atmosphere prior to the gas filtration medium. The output sensor reflects readings from at least one metallic corrosion detector, and can embody metallic corrosion detector 68. Low levels of incremental corrosion rates near the origin of the graph indicates that the purification medium is efficiently and effectively "scrubbing" the corrosive agents out of the stream of gas flow. At time t = t,, the output sensor is experiencing higher incremental corrosion rates because the gas filtration medium is partially used up. At time t ^■= t₂, however, when the incremental corrosion rate read by the output sensor is equal to the incremental corrosion rate read by the input sensor, the gas filtration medium is used up and needs replacement. Thus, Fig. 10 illustrates a gradual deterioration of the filtration medium of the gas filtration system from time t = t₀ to time_^ t = t-, due to corrosivity in the environment.

Fig. 11, however, illustrates the incremental corrosion rate remaining generally constant at the input sensor upstream of the gas flow before reaching the filtration medium. Likewise, the incremental corrosion rate experienced by the output sensor remains relatively low a: 1 constant from the origin, and sharply increases from t me t = t₀ to time t = t₂, whereby at time t = t₂, the corrosion rate experienced by the input is equal to the corrosion rate experienced by the output sensor. Accordingly, at time t = t₂ the gas filtration medium is no longer effective against corrosive agents in the gas stream, and the medium needs replacement. Fig. 11, therefore, illustrates an example of a filtration medium, which filters the stream of gas effectively for some time and is then fully exhausted between time t = t₀ and time t

Another example of an application of the present invention is shown in Fig. 12, whereby an electronic computer hardware system 70 is a portable housing, and comprises vents 71 on one of its side walls which allow air to flow through the hardware, such as the circuit boards 72, 74, and 75. A fan 76, usually located on the opposite and opposed side wall from the side wall having the vents 71, of the electronic computer hardware 70 draws air out of the hardware in the direction of the arrows for cooling purposes. The corrosion profiling and diagnostic system 78 can, therefore, be mounted directly on the circuit boards 72, 74, and 75 spaced at different locations on each board. In this application, the corrosion profiling system 78 can be located alongside or in the near vicinity of the corrodable elements on a computer system so as to remain stealthy and rather tamper-resistant to an uninformed user of the computer. The corrosion level readings from each of the profiling systems 78, therefore, can then be compared and analyzed so as to determine the spatial fitness profile of the electronic system.

The invention has been disclosed and described herein in terms of preferred configurations and methodologies. However, it will be obvious to those skilled in the art that numerous variations of the illustrated embodiment could be implemented within the scope of the invention. For example, the present invention could include other sensors implemented in addition to, or in replacement of, the temperature and humidity sensors. Such sensors can comprises sensors, such as a sensor for measuring the vibration of elements within the housing, and the like.

These and other additions, deletions, and modifications might well be made to the exemplary embodiments illustrated herein without departing from the spirit and scope of the invention as set forth in the claims.

Claims

I claim :

1. An apparatus for determining the fitness for an intended use of a system subject to deterioration induced by its environment, comprising: means for moving gas across the system, at least first and second metallic test specimen spaced from each other in the path of the gas flow, detector means for measuring the amount of corrosion of said first and second metallic test specimen, means for comparing the amount of measured corrosion of said first test specimen relative to the amount of measured corrosion of said second test specimen, and a data logging means for recording the compared amounts of measured corrosion of said specimen, so that the corrosion of the first test specimen relative to the corrosion of the second test specimen can be used to obtain the fitness of the system.

2. The apparatus for determining the fitness for an intended use of a system as described in claim 1 and wherein said means for comparing the amount of measured corrosion of said first test specimen relative to said second test specimen further comprises means for solving for the rate of corrosion of at least said first and second test specimen.

3. The apparatus for determining the fitness for an intended use of a system as described in claim 1 and further comprising means for concealing said detector means and said data logging means from the sight of a user of the system.

4. The apparatus for determining the fitness for an intended use of a system as described in claim 1 and wherein said detector means and said data logging means are tamper resistant.

5. The apparatus for determining the fitness for an intended use of a system as described in claim 1 and wherein said metallic test specimen each comprise at least one strip of material having an exposed metal surface.

6. The apparatus for determining the fitness for an intended use of a system as described in claim 5 and wherein said exposed metal surface is selected from the group of elements consisting of: copper, gold, nickel, silver, and zinc.

7. The apparatus for determining the fitness for an intended use of a system as described in claim 1 and wherein said detector means comprises means for measuring the thickness of corrosion on at least said first and second metallic test specimen.

8. The apparatus for determining the fitness for an intended use of a system as described in claim 1 and wherein said data logging means comprises a microprocessor.

9. The apparatus for determining the fitness for an intended use of a system as described in claim 1 and wherein said apparatus further includes electrical power means for electrically activating said apparatus.

10. The apparatus for determining the fitness for an intended use of a system as described in claim 9 and wherein said electrical power means comprises a battery.

11. The apparatus for determining the fitness for an intended use of a system as described in claim 9 and wherein said electrical power means comprises a solar cell.

12. The apparatus for determining the fitness for an intended use of a system as described in claim 9 and wherein said electrical power means includes switch means for intermittently connecting said electrical power means to said apparatus so as to take intermittent measurements of the amount of corrosion on at least said first and second metallic test specimen.

13. The apparatus for determining the fitness for an intended use of a system as described in claim 1 and wherein said system, the fitness of which is determined, comprises a gas purification system.

14. The apparatus for determining the fitness for an intended use of a system as described in claim 1 and wherein said system,the fitness of which is determined, comprises the purification medium of a gas purification system.

15. The apparatus for determining the fitness for an intended use of a system as described in claim 13 and wherein at least one of said metallic test specimen is integral to said gas purification system.

16. The apparatus for determining the fitness for an intended use of a system as described in claim 13 and wherein said gas purification system comprises a replaceable gas purification medium and at least one metallic test specimen.

17. The apparatus for determining the fitness for an intended use of a system as described in claim 14 and wherein the deterioration induced by the environment is reduction of the effectiveness of the purification medium of said gas purification system.

18. The apparatus for determining the fitness for an intended use of a system as described in claim 1 and wherein said system comprises an electronic system.

19. The apparatus for determining the fitness for an intended use of a system as described in claim 1 and wherein the deterioration induced by the environment is corrosion of a metallic component of the system.

20. The apparatus for determining the fitness for an intended use of a system as described in claim 1 and wherein said test specimen are spatially arranged from one another so as to provide a profile of deterioration levels about the system.

21. An apparatus for determining the fitness for an intended use of a system in a housing subject to deterioration induced by its environment in the housing, comprising: at least first and second metallic test specimen spaced from each other in a common atmosphere about the system in said housing, detector means for measuring the amount of corrosion of said first and second metallic test specimen, means for comparing the amount of measured corrosion of said first test specimen relative to the amount of measured corrosion of said second test specimen, and data logging means for recording the compared measured corrosion, so that the corrosion of the first test specimen relative to the corrosion of the second test specimen can be used to obtain a spatial fitness profile of the system.

22. The apparatus for determining the fitness for an intended use of a system as described in claim 21 and wherein said detector means comprises said first and second test specimen each formed of a material having an exposed metal surface.

23. The apparatus for determining the fitness for an intended use of a system as described in claim 22 and wherein said exposed metal surface is selected from the group of elements consisting of: copper, gold, nickel, silver, and zinc.

24. The apparatus for determining the fitness for an intended use of a system as described in claim 21 and wherein said means for comparing the amount of measured corrosion of said first 'test specimen relative to said second test specimen further comprises means for solving for the rate of corrosion of at least said first and second test specimen.

25. The apparatus for determining the fitness for an intended use of a system as described in claim 21 and further comprising means for concealing said detector means and said data logging means from the sight of ,a user of a system.

26. The apparatus for determining the fitness for an intended use of a system as described in claim 21 and wherein said detector means and said data logging means are tamper resistant.

27. The apparatus for determining the fitness for an intended use of a system as described in claim 21 and wherein said detector means comprises means for measuring the thickness of corrosion on at least said first and second metallic test specimen.

28. The apparatus for determining the fitness for an intended use of a system as described in claim 21 and wherein said data logging means comprises a microprocessor.

29. The apparatus for determining the fitness for an intended use of a system as described in claim 21 and wherein said apparatus further includes electrical power means for electrically activating said apparatus.

30. The apparatus for determining the fitness for an intended use of a system as described in claim 29 and wherein said electrical power means comprises a battery.

31. The apparatus for determining the fitness for an intended use of a system as described in claim 29 and wherein said electrical power means comprises a solar cell.

32. The apparatus for determining the fitness for an intended use of a system as described in claim 29 and wherein said electrical power means includes switch means for intermittently connecting said electrical power means to said apparatus so as to take intermittent measurements of the amount of corrosion on at least said first and second metallic test specimen.

33. The apparatus for determining the fitness for an intended use of a system as described in claim 21 and wherein said system, the fitness of which is determined, comprises a gas purification system.

34. The apparatus for determining the fitness for an intended use of a system as described in claim 21 and wherein said system, the fitness of which is determined, comprises the purification medium of a gas purification system.

35. The apparatus for determining the fitness for an intended use of a system as described in claim 33 and wherein said one of said metallic test specimen is integral to said gas purification system.

36. The apparatus for determining the fitness for an intended use of a system as described in claim 33 and wherein said gas purification system comprises a replaceable gas purification medium and at least one metallic test specimen.

37. The apparatus for determining the fitness for an intended use of a system as described in claim 34 and wherein the deterioration induced by the environment is reduction of the effectiveness of the purification medium of said gas purification system.

38. The apparatus for determining the fitness for an intended use of a system as described in claim 21 and wherein said system comprises an electronic system.

39. The apparatus for determining the fitness for an intended use of a system as described in claim 21 and wherein the deterioration induced by the environment is corrosion of a metallic component of the system.

40. The apparatus for determining the fitness for an intended use of a system as described in claim 21 and wherein said test specimen are spatially arranged from one another so as to provide a profile of deterioration levels about the system.

41. The apparatus for determining the fitness of a system for an intended use as described in claim 1 and wherein each of said test specimen comprise the same characteristics for measuring the amount of corrosion experienced by the system.

42. The apparatus for determining the fitness of a system for an intended use as described in claim 21 and wherein each of said test specimen comprise the same characteristics for measuring the amount of corrosion experienced by the system.