WO1993021512A1

WO1993021512A1 - Deterioration monitoring system

Info

Publication number: WO1993021512A1
Application number: PCT/US1993/002463
Authority: WO
Inventors: David W. Hughes; Michael W. Osborne
Original assignee: Purafil, Inc.
Priority date: 1992-04-16
Filing date: 1993-03-23
Publication date: 1993-10-28
Also published as: AU3922793A

Abstract

The deterioration monitoring system (25) comprises a metallic corrosion detector (10) for sensing levels of corrosion and generating an uncorrected signal, a calibration and correction algorithm (27) for converting the uncorrected signal to a corrected signal representing true-corrosion, a comparison step (29) for comparing the amount of measured corrosion with a user-selected or industry-predetermined standard corresponding to the highest acceptable quantity of deterioration, and a data logger (30) for storing the values of the amount of measured corrosion. The deterioration monitoring system (25) can be placed in a portable housing (26 or 36), such as a shipping container (44), a computer hardware system (50), a camera (60), or any other system subject to deterioration induced by its environment so as to monitor levels of corrosion.

Description

DETERIORATION MONITORING 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 monitoring corrosion and deterioration in a portable housing, such as in the housing of an electronic system such as a computer or in a shipping container for an electronic system.

BACKGROUND OF THE INVENTION

Certain components and devices, such as metal- containing components within electronic systems, are highly sensitive and subject to atmospheric corrosivity. Prolonged exposure to such atmospheric corrosivity has harmful effects on the components and devices, and can cause deterioration and failure of the system 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-billion concentrations, the presence of these gases can lead to the failure of electronic equipment due to corrosion of circuitry in as little time as several months, depending on the concentration of the corrosive agents. Other factors which affect rates of corrosion include gas temperature and relative humidity.

Because of the potential of costly down time from electronic failures and safety factors, industries are becoming more concerned with measuring, monitoring and regulating the environment in which such electronic systems reside.

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 buildup of corrosion on similar substrates contained in the same environment. These types of projections are vital to the electronics industry for formulating the scope of warranty coverage, particularly in limiting such coverage due to excessively corrosive environments at the customer's installation.

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. In highly corrosive environments, such as in a pulp and paper mill or in an oil refinery, the corrosion formed during this period of time on certain electronic systems is enough to partially destroy some of the electronic components and devices within the systems.

Another disadvantage in the present method is that once the strip of copper is corroded and measured for collective corrosion in the room, 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.

Many 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 inputs to a microprocessor. The microprocessor scans the signals generated and records in a memory module excursions from set conditions which last 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 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. Littler discloses that when a crystal with a 3.5 MHz oscillating frequency is utilized, a decrease in thickness of one A is said to be equivalent to an increase in frequency of one 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) . Additionally, Littler does not address the need for sensing atmospheric factors such as relative humidity, temperature, 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 30 days in advance so as to predict when failures might occur. All of the above-mentioned patents and products involve methods and apparatuses for sensing corrosion in a room, such as a computer control room. None of the above- mentioned systems, however, disclose a system for use in a portable housing, such as in the cabinet of a computer or in any other electronic system or shipping container for the system. Thus, a need exists for an apparatus which can be placed within the housing of an actual electronic system or in its^" shipping container so as to provide a more accurate indication of deterioration of the components of the specific electronic equipment during storage, installation and operation, rather than a device which monitors an entire room filled with electronic equipment. Since different computers or systems within a room deteriorate at different rates, the type of local information obtained frommonitoring each system singularly is much more indicative of the actual condition of the individual pieces of equipment.

None of the above-mentioned patents or products disclose a device for monitoring deterioration and other factors that the system is exposed to between the point of manufacture and the point of installation. In some instances, the system has been exposed to high levels of corrosive gases, and other factors such as unsuitable temperatures, humidity, and physical shock during shipping, handling and storage. Thus, a need exists for an environmental deterioration monitoring system which not only monitors electronic systems while in operation, but also monitors the system during shipping, handling and storage.

SUMMARY OF THE INVENTION As described, the deterioration monitoring system comprises an apparatus and a method for monitoring corrosion of a device or system subject to deterioration induced by its environment. The deterioration monitoring system carries out the steps of measuring the amount of corrosion of at least one metallic test specimen located in a portable housing, comparing the amount of measured corrosion of the test specimen with a predetermined standard corresponding to the highest acceptable quantity of deterioration of the system, and generating a signal for indicating the fitness of the system. One embodiment of the invention applies the use of a crystal, such as a piezoelectric crystal for measuring the amount of corrosion in a portable housing, such as in the cabinet for an electronic system or in its shipping container. The crystal can be a piezoelectric crystal which has a constant natural oscillation frequency and whose oscillation frequency is dependent on the mass on its surface. If the coating is applied to the crystal which interacts or reacts with the atmosphere of its environment, the mass on the crystal surface will become altered, thus, altering the oscillation frequency of the crystal. The mass on the crystal surface can be a corrodible metallic substance, such as copper, nickel, or silver.

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. 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. Measurements of the amount of corrosion experienced by the piezoelectric crystal can be real-time, on-line and continuous measurements which are registered and can be converted into a value. This value can reflect a calibration and a correcting step which accounts for any deviation in the atmosphere or the apparatus during each interval of time. Such a corrected value is compared to a predetermined standard, which can be user-selectable and is related to the highest acceptable quantity of deterioration. A signal is then formed for indicating the fitness of the electronic system, and can be stored or can be displayed to the user. The predetermined standard which is used during the comparison step can be determined by applying standards, as set by the ISA, or can be user-selectable. Therefore, the user has the option of selecting an appropriate "trip" or "trigger" point depending on the environment which the system will be placed.

The present invention also can embody a small, stealthy unit, whereby the user of the system might not recognize its presence. Such a unit can be located directly on the printed wiring board or can be disguised so as to control access to the unit. Additionally, the unit can be normally dormant, whereby the unit is capable of turning itself on at regular intervals or when certain atmospheric conditions are detected or experienced by the unit.

The present invention also can include a variety of sensors. Such sensors can include sensors for measuring temperature and relative humidity. These signals 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 and incremental corrosion rate, and can be related to ISA standards or other industry-accepted standards. The output also can predict and project the ultimate reliability of the device, component or system.

In other embodiments of the present invention, the step of measuring the amount of corrosion of at least one metallic test specimen located in the system can comprise measuring the light reflected from a metallic material or measuring an electrical resistance across a metallic material. Normally, the deterioration monitor is used in the general environment in which the device, component or system operates. However, the present invention also can be used as a warranty verification system, whereby the deterioration monitor can be installed within or in the vicinity of the device, component or system at its point of manufacture and can monitor real-time environmental conditions, as well as physical conditions that the device, component or system has been exposed to during the time interval between the point of manufacture and the point of installation. When the system arrives at its destination, a service or set-up person can obtain information from the deterioration monitor so as to determine whether or not the overall fitness of the system was compromised during shipping, handling and storage. From this diagnostic information, the manufacturer can determine accurate warranty limitations and coverages for the particular device, component or system.

It is, therefore, an object of the present invention to provide an environmental monitor which is small and stealthy and can be mounted in a portable housing, such as within the housing of a device, component or system or inside a shipping container and which detects and reports -li¬ the condition of the environment within the housing or container.

Another object of the present invention is to provide a monitor for mounting inside the cabinet of an electronic system, such as a computer, and which can generate a signal recognized as conforming to the industry standard ^'for indicating the deterioration of and therefore the fitness of the electronic system.

A further object of the present invention is to provide an electronic system, such as a computer, which includes an environmental monitor within the housing of the computer, with the monitor including a variety of sensors, such as sensors for temperature, corrosion, and relative humidity. Another object of the present invention is to provide such a system with an environmental monitor, with the monitor constructed and arranged to allow the user to select the predetermined standards to which the values measured by the monitor are compared. It is another object of the present invention to provide a portable deterioration monitor for an electronic system which can be battery operated and can operate without an exterior power source so as to detect the environment within the housing of the electronic system before the electronic system is delivered to and connected to its normal power source. A further object of the present invention is to provide atmospheric and environmental information encountered by the components of an electronic system before and/or during use of the system so as to aid the manufacturer of the system to determine warranty limitations of the system.

Amore 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 corrosion detector.

Fig. 2 is a side view of another embodiment of the metallic corrosion detector.

Fig. 3 is a side view of yet another embodiment of the metallic corrosion detector. Fig. 4 is a schematic diagram illustrating the process used to indicate the fitness of a system using any of the above-mentioned metallic corrosion detectors.

Fig. 5 is a schematic diagram illustrating another process of indicating the fitness of a system using any of the above-mentioned metallic corrosion detectors. Fig. 6 is a side view illustrating one application of the present invention.

Fig. 7 is a perspective view illustrating another application of the present invention. Fig. 8 is a perspective view illustrating yet another application of the present invention.

Fig. 9 is a schematic diagram illustrating an interval timer implemented in any of the metallic corrosion detector embodiments of the present invention. Fig. 10 is a bar graph illustrating the interval timing concept of Fig. 9

Fig. 11 is a schematic diagram illustrating another embodiment'of the deterioration monitoring system including a relative humidity sensor, a temperature sensor, and an accelerometer.

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 a metallic corrosion detector 10 or 37 of Figs. 4 and 5, respectively. One embodiment of the metallic corrosion detector 10 comprises one or more quartz crystals, such as piezoelectric crystals 11 (Fig. l) having one side 12 and another side 14, and including an approximately 30 A thick layer of chromium 15 bonded to or deposited on each of the sides 12 and 14 of the piezoelectric crystal 11. A layer of a corrodible metallic substance 16 is then bonded or deposited onto the layer of chromium 15. The layer of chromium 15 thereby serves to bond the corrodible metallic substance 16 to the 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 detector surface 10, 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. Additionally, multiple crystals can be incorporated within one detection circuit 10, and can carry different corrodible metallic substances 16, such as copper, silver, and nickel. Fig. 2 shows another embodiment of the metallic corrosion detector 10 and 37 of Figs. 4 and 5 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 one or more metallic strips 19 to the atmosphere for a period of time, ranging from one to three months, the change in thickness of corrosive buildup on the strips 19 occurs and the thickness of corrosion is measured using a complex coulometric reduction procedure, known to those skilled in the art. Alternatively, elements within the circuit of the metallic corrosion detector 19 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 19. 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 metallic strip 19.

Another embodiment of the metallic corrosion detector

10 or 37 of Figs. 4 and 5 comprises a metallic strip 22

(Fig. 3) of material such as copper, iron, steel, zinc, nickel or silver which would each find use in different systems or corrosive environments. After one or more of the metallic strips 22 have been exposed to the atmosphere for a period of time, corrosion of the strip occurs which changes the electrical resistance of the strip and the changes in the resistance across the metallic strip 22 can be measured by an ohm meter 24. Such changes in electrical resistance occur as corrosion proceeds in time and are, in part, due to a reduction of the cross-sectional area of the metallic strip 22.

Fig. 4 shows a schematic diagram of a deterioration monitoring system 25, including the metallic corrosion detector 10 and other elements of the system which are enclosed within a portable housing or cabinet 26, whereby certain conditions are present in the housing and can be monitored by the present invention. The system 25 comprises one or more metallic corrosion detectors 10, which can take the form of any of the embodiments shown in Figs. 1 through 3. The corrosion detector 10 senses corrosion levels in the environment and generates a raw or uncorrected signal. The uncorrected signal is transmitted to a circuit having a calibration and correction algorithm 27 which converts the raw, uncorrected signal to a corrected signal, which indicates true-corrosion. Additionally, the calibration and correction algorithm 27 may also include conventional atmospheric sensors (not shown) , such as a relative humidity sensor and a temperature sensor. Such atmospheric condition sensors are of conventional design, such as a National LM35, which can be used as a temperature sensor, and the humidity sensor can be a MINICAP 2 model, manufactured by Panametrics. Moreover, the calibration and correction algorithm 27 preferably can be incorporated into a programmable microprocessor using techniques which are well known to those skilled in the art.

Once the corrected signal or true-corrosion level is determined) the value is transmitted to a comparison step 29, whereby the corrected signal is compared to a standard, such as a standard determined by the ISA, or a user- selectable trip point, which is determined by the user. This comparison step can be performed by an electronic comparator, which is commonly known in the prior art. Thus, a user has the option of comparing the corrected signal to a standard, such as the ISA, or the user can select any standard, so as to serve the function of monitoring the deterioration of the system. A data logger 30, such as a memory chip, can then store any readings from the comparison 29 step so as to notice any deviation in the corrosion levels, the temperature, or the relative humidity from a standard or user-predetermined corrosion level, temperature or relative humidity. Fig. 4 also shows an electronic receiver 31 which can be located exteriorly of the housing and can be coupled with the data logger at a serial port 32. Therefore, a user can generate a report from the data logger 30 which indicates the general fitness of the system being monitored.

Fig. 5 shows a schematic diagram of another embodiment 35 of the deterioration monitoring system, including a metallic corrosion detector 37 which is enclosed within a housing 36, whereby certain environmental conditions are present in the housing and can be monitored by the deterioration monitoring system 35. Similar ^• to the embodiment of Fig. 4, the metallic corrosion detector 37 can take the form of any of the detectors shown in Figs. 1 through 3 and senses corrosion in the environment as well as generates an uncorrected signal. The uncorrected signal then enters a circuit including a calibration and correction algorithm 38 which converts the uncorrected signal to a corrected signal, indicating true-corrosion. Similar to the embodiment shown in Fig. 4, sensors for relative humidity and temperature (not shown) can determine the humidity and the temperature effects on the signal so as to generate a true-corrosion signal or value. A data logger 40, as shown in Fig. 5, stores the corrected signals generated by the calibration and correction algorithm. Additionally, a comparison step 41 can be incorporated to compare the signals stored in the data logger. Such a comparison step can be performed by a comparator, generally known in the art which can compare the corrected signal to a user-selectable standard, or an industry-set standard.

The present invention can have many applications, such as the applications illustrated in Figs. 6 through 8. For example, Fig. 6 shows a shipping container 44 with a deterioration monitoring system 45 mounted to the container 44 by a bracket 46. The deterioration monitoring system 45 thereby monitors the environment and atmospheric conditions of the shipping container carrying boxes 47 containing electronic devices or other corrosion-sensitive systems. Several layers of protective material 49, such as styrofoam material, also are shown between the layers of the boxes 47 of the corrosion-sensitive system. This application of the deterioration monitoring system is particularly desirable for manufacturers as well as purchasers of the corrosion- sensitive devices.

For example, the deterioration monitoring system can be installed inside the shipping container 44 at its point of manufacture and can monitor the environmental conditions that the corrosion-sensitive devices have been exposed to during the time interval between the point of manufacture and the point of installation. Thus, when the system arrives at its destination, a service person can obtain information from the deterioration monitoring system so as to determine whether or not the overall fitness of the system was compromised during shipping, handling and storage. From this diagnostic information, the manufacturer can set accurate warranty limitations and coverages for the corrosion-sensitive devices and the purchaser can determine accurate fitness information of the system upon receipt.

Another example of an application of the present invention is shown in Fig. 7 whereby an electronic computer hardware system 50 includes on one of its side walls, such as side wall 51, a deterioration monitoring system 52. The deterioration monitoring system 52 can be mounted to the side wall 51 by a mounting bracket 54 and can include an exterior port 55 for connecting to a receiver 58 so as to read the corrosion level data. Thus, the corrosion monitoring system 52 is located alongside or in the near vicinity of hardware electronic boards 56, which hold the corrodible elements of the computer system. The exterior receiver 58 can access the corrosion data from time to time by connection with the port 55 of the corrosion monitoring system 52. The corrosion level readings can then be analyzed so as to determine the general fitness of the computer system 50. Fig. 8 shows another ex-ample of an application of the present invention, whereby a camera 60 includes a deterioration monitoring system (not shown) . In this embodiment, the deterioration monitoring system would be located at an inner portion of a side wall, such as side wall 61. An exterior port 62 can be used to receive corrosion level information from the deterioration monitoring system. Thus, the present invention can embody a small, stealthy unit, whereby the user of the system might not even recognize its presence. Such a small, stealthy unit can even be tamper resistant so as to control access to the deterioration monitoring system.

The deterioration monitoring system of the present invention can be portable 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 at regular intervals or when certain atmospheric conditions are detected, for example, by using an interval timer 71 to activate an "on- off" switch 72 (Fig. 9) . The switch then supplies power 70 to the corrosion monitoring system, such as system 25 or 35, which, after an appropriate warm-up period, makes a corrosion measurement as described above. After performing such a measurement, the system then is shut down and remains dormant until the next selected time interval- Fig. 10 illustrates the concept of interval timing. During time periods 80 when the unit is dormant, there is very little power consumed because the corrosion monitoring system is off, and the only power required is that necessary to maintain the activity of the interval timer. The power consumption goes up during measurement periods 81 because the corrosion monitoring system is active during these periods. The time intervals may be of arbitrary frequency and duration. For example, measurements may be daily, weekly, monthly and so forth.

It is possible to combine the output of several types of sensors as shown in Fig. 11. This embodiment of the deterioration monitoring system 95 includes a metallic corrosion detector 90, within a portable housing 96, which can embody, any or all of the corrosion detectors of Figs. 1 through 3. As shown in Fig. 11, an uncorrected signal is generated by the detector 90 and is transmitted to a circuit having a calibration and correction algorithm 91. The algorithm 91 can include outputs from a relative humidity sensor 92 and a temperature sensor 93 which account for the effects of relative humidity and temperature to indicate a corrected signal which indicates true-corrosion. The corrected signal and a signal generated by an accelerometer 97, which indicates levels of acceleration experienced by elements in the housing 96, can then enter a data-logger 98 so as to be recorded. A comparison step 99 can be utilized so as to compare the data recorded by the data logger 98 to a user-selected or an industry-selected standard. Finally, an option of outputting the data is available. Therefore, data relating to corrosion is augmented with information about temperature, relative humidity and accleration in order to obtain a more complete scenario of the environment within the indicated housing.

Other sensors can be implemented in addition to or in replacement of the accelerometer. Such sensors can comprise sensors, such as a sensor for measuring the vibration of elements within the housing, a sensor for measuring electrostatic charge applied to elements in the housing, and a sensor for measuring particulate matter in the atmosphere within the housing. While the invention has been described in relation to these preferred embodiments, it will be apparent to those skilled in the art that the invention is susceptible to additional embodiments without departing from the spirit and scope of the invention. Therefore, it is intended that the invention not be limited except by the claims.

Claims

I Claim:

1. A method of determining the fitness for an intended use of a system subject to deterioration induced by its environment and positioned in a portable housing, comprising the steps of: measuring the amount of corrosion of at least one metallic test specimen located in the housing in proximity to the system, comparing the amount of measured corrosion of the test specimen with a predetermined standard corresponding to the highest acceptable quantity of deterioration of the system, in response to the amount of measured corrosion of the test specimen being compared to the standard, generating a signal for indicating the fitness of the system.

2. The method of claim 1 and wherein the step of comparing the amount of measured corrosion of the test specimen with a predetermined standard further includes the step of a user of the method selecting of the predetermined standard.

3. The method of claim 1 and wherein the step of measuring the amount of corrosion of the metallic test specimen comprises converting the measurement to a value, and wherein the step of comparing the amount of measured corrosion of the test specimen with the predetermined standard comprises comparing the value of the measured corrosion -of the test specimen with the predetermined standard, which is related to the highest acceptable quantity of deterioration.

4. The method of determining the fitness of a system positioned in a portable housing as set forth in claim l and wherein the step of measuring the amount of corrosion of a metallic test specimen located in the portable housing comprises making measurements of the amount of corrosion of the test specimen over intervals of time and recording the measurements.

5. The method of determining the fitness of a system positioned in a portable housing as set forth in claim 1 and further including the step of measuring at least one other condition within the portable housing, including: measuring the temperature of the environment within the housing, measuring the relative humidity of the environment within the housing. measuring the vibration of the elements in the housing, measuring the acceleration of elements in the housing, measuring the electrostatic charge applied to the elements in the housing, and measuring the particulate matter in the atmosphere within the housing.

6. The method of determining the fitness of a system positioned in a portable housing as set forth in claim 1 and wherein the step of measuring the amount of corrosion of a metallic test specimen located in the portable housing comprises: measuring the vibration frequency of a crystal coated with a metallic material.

7. The method of determining the fitness of a system positioned in a portable housing as set forth in claim 1 and wherein the step of measuring the amount of corrosion of a metallic test specimen located in the housing comprises: measuring light reflected from a metallic material.

8. The method of determining the fitness of a system positioned in a portable housing as set forth in claim 1 and wherein the step of measuring the amount of corrosion of a metallic test specimen located in the housing comprises: measuring an electrical resistance across a metallic material.

9. The method of determining the fitness of a system positioned in a portable housing as set forth in claim 1 and wherein the system comprises an electronic system.

10. The method of determining the fitness of a system positioned in a portable housing as set forth in claim 1 and wherein the deterioration induced by the environment is corrosion of a metallic component of the system.

11. An apparatus for determining the fitness for an intended use of a system subject to deterioration induced by its environment and positioned in a portable housing, comprising: at least one metallic test specimen, detector means in said housing for measuring the amount of corrosion on said metallic test specimen in said portable housing, means for relating the amount of measured corrosion to a value corresponding to the amount of deterioration experienced by the system, means for comparing the amount of measured corrosion of the test specimen with a predetermined standard corresponding to the highest acceptable quantity of deterioration of the system, and a data logging means for recording the fitness of the system in response to the amount of measured corrosion of the test specimen, so that the apparatus can be installed in the portable housing for tracking the amount of deterioration of the system over a period of time.

12. The apparatus for determining the fitness of a system positioned in a portable housing for an intended use of claim 11 and wherein said detector means and said logging means are concealed from the sight of a user.

13. The apparatus for determining the fitness of a system positioned in a portable housing for an intended use of claim 11 and wherein said detector means and said data logging means are tamper resistant.

14. The apparatus for determining the fitness of a system positioned in a portable housing for an intended use of claim 11 and wherein said detector means comprises at least one strip of material having an exposed metal surface.

15. The apparatus for determining the fitness of a system positioned in a portable housing for an intended use of claim II and wherein said apparatus further includes electrical power means for electrically activating said apparatus.

16. The apparatus for determining the fitness of a system positioned in a portable housing for an intended use of claim 15 and wherein said power means comprises a battery.

17. The apparatus for determining the fitness of a system positioned in a portable housing for an intended use of claim 15 and wherein said power means comprises a solar cell.

18. The apparatus for determining the fitness of a system positioned in a portable housing for an intended use of claim 15 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 said metallic test specimen.

19. The apparatus for determining the fitness of a system positioned in a portable housing for an intended use of claim 11 and wherein said data logging means comprises a microprocessor.

20. The apparatus for determining the fitness of a system positioned in a portable housing for an intended use of claim 11 and wherein said detector means comprises means for measuring the thickness of corrosion on the metallic test specimen in said housing.

21. The apparatus for determining the fitness of a system positioned in a portable housing for an intended use of claim 11 and wherein said system comprises an electronic system.

22. The apparatus for determining the fitness of a system positioned in a portable housing for an intended use of claim 11 and wherein the deterioration induced by the environment is corrosion of a metallic component of the system.

AMENDED CLAIMS

[received by the International Bureau on 23 September 1993 (23.09.93); original claims 8-12 cancelled; claims 13-22 renumbered as claims 8-17

5 pages)]

1. A method of measuring the corrosive deterioration of a system contained within a portable housing opened to an uncontrolled external environment, said system being subject to deterioration induced by the external environment, for determining the fitness for an intended use of the system, comprising the steps of: placing at least one metallic test specimen in proximity to the system in a location within the housing subject to movement of the environment through the portable housing, measuring the amount of corrosion of the metallic test specimen, comparing the amount of measured corrosion of the test specimen with a predetermined standard corresponding to the highest acceptable amount of deterioration of the system, n response to the amount of measured corrosion of the test specimen being compared to the standard, generating a signal for indicating the results of the comparison and hence the fitness of the system.

2. The method of claim 1 and wherein the step of comparing the amount of measured corrosion of the test specimen with a predetermined standard further includes the prior step of selecting the predetermined standard.

3. The method of claim 1 and wherein the step of measuring the amount of corrosion of the metallic test specimen comprises converting the measurement to a value, and wherein the step of comparing the amount of measured corrosion of the test specimen with the predetermined standard comprises comparing the value of the measured corrosion of the test specimen with the predetermined standard, which is related to the highest acceptable amount of deterioration.

4. The method of claim 1 and wherein the step of measuring the amount of corrosion of a metallic test specimen located in the portable housing comprises^"making measurements of the amount of corrosion of the test specimen over intervals of time and recording the measurements.

5. The method of claim 1 and further including the step of measuring at least one other condition within the portable housing, including: measuring the temperature of the environment within the housing, measuring the relative humidity of the environment within the housing, measuring the vibration of the elements in the housing, measuring the acceleration of elements in the housing, measuring the electrostatic charge applied to the elements in the housing, or measuring the particulate matter in the atmosphere within the housing. 6. The method of claim 1 and wherein the step of measuring the amount of corrosion of a metallic test specimen located in the portable housing comprises: measuring the vibration frequency of a crystal coated with a metallic material.

7. An apparatus for measuring the corrosive deterioration of a system contained within a portable housing open to an uncontrolled external environment, said system being subject to deterioration induced by the external environment, for determining the fitness for an intended use of a system, comprising: at least one metallic test specimen positioned in proximity to the system in a location within the housing subject to movement of the environment through the portable housing, detector means in said housing for measuring the amount of corrosion from the environment on said metallic test specimen in said portable housing, means for relating the amount of measured corrosion to a value corresponding to the amount of deterioration experienced by the system, means for comparing the amount of measured corrosion of the test specimen with a predetermined standard corresponding to the highest acceptable amount of deterioration of the system, and a data logging means for recording the fitness of the system in response to the amount of measured corrosion of the test specimen, said apparatus being installed in the portable housing for tracking the amount of deterioration of the system over a period of time.

8. The apparatus of claim 7 and wherein said detector means and said data logging means are mounted within the housing in an inaccessible to human contact position when the housing is closed.

9. The apparatus of claim 7 and wherein said detector means comprises at least one strip of material having an exposed metal surface.

10. The apparatus of claim 7 and wherein said apparatus further includes electrical power means for electrically activating said apparatus.

11. The apparatus of claim 10 and wherein said power means comprises a battery.

12. The apparatus of claim 10 and wherein said power means comprises a solar cell.

13. The apparatus of claim 10 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 said metallic test specimen. 14. The apparatus of claim 7 and wherein said data logging means comprises a microprocessor.

15. The apparatus of claim 7 and wherein said detector means comprises means for measuring the thickness of corrosion on the metallic test specimen in said housing.

16. The apparatus of claim 7 and wherein said system comprises an electronic system.

17. The apparatus of claim 7 and wherein the deterioration induced by the uncontrolled external environment is corrosion of a metallic component of the system.