The failure rate does not include drive returns with "no trouble found", excessive shock failure, or handling damage. The failure rate can be used interchangeably with MTTF and MTBF as per calculations described earlier. For example, a reliability of 97.5% at 50 hours means that if 1000 new components are put into the field, then 975 of those components are expected to last at least 50 hours of operation. Reliability is also an important consideration during the product design process, where MTBF estimates can help improve reliability before a product is even made. {\displaystyle \Delta t} It can be seen from the preceding equation that the two functions are distinctly different. Failure rate can be defined as the anticipated number of times that an item fails in a specified period of time. By looking at the elements that contribute to the definition of meantime between failures, we can see how to increase MTBF either we can reduce the number of failures or we can increase the total time the asset spends operating correctly. Each time a piece of equipment occurs is a perfect opportunity to step back and look for any underlying causes of the failure that you can address. Acrobat Distiller 4.05 for Windows; modified using iTextSharp 4.1.6 by 1T3XT A common model is the exponential failure distribution. It is an indication of how long a electrical or mechanical system typically operates before failing. Some people get confused and think that MTBF is actually a measure of useful life. n = sample size Note that this is a conditional probability, where the condition is that no failure has occurred before time t Figure 1.2. Design Verification Plan and Report (DVP&R) requires a sufficient sample size to justify performance inferences about a design. Copyright 2005-2023 BMC Software, Inc. Use of this site signifies your acceptance of BMCs, Apply Artificial Intelligence to IT (AIOps), Accelerate With a Self-Managing Mainframe, Control-M Application Workflow Orchestration, Automated Mainframe Intelligence (BMC AMI), availability metrics and the 9s of availability. These failures are caused by mechanisms that degrade the strength of the component over time such as mechanical wear or fatigue. The following literature was referenced for system reliability and availability calculations described in this article: 86% of global IT leaders in a recent IDG survey find it very, or extremely, challenging to optimize their IT resources to meet changing business demands. An SLA breach not only incurs cost penalty to the vendor but also compromises end-user experience of apps and solutions running on the cloud network. First, the sample variance is given by. As these defects are eliminated, the curve levels off into the second zone. This data can then be used to assess when maintenance or replacement is required and to improve the overall performance of the system, by focusing on improving MTBF. Redundancy models can account for failures of internal system components and therefore change the effective system reliability and availability performance. Where: Shaoping Wang, Hong Liu, in Commercial Aircraft Hydraulic Systems, 2016, Failure rate is the limit of the probability that a failure occurs per unit time interval t given that no failure has occurred before time t. The failure rate is the conditional probability, which can be expressed as. What are Smart Contracts and How are Enterprises Using Them? 4 0 obj
Note that the pdf is always normalized so that its area is equal to 1. Yi Xiao-Jian, Mu Hui-Na, in Goal Oriented Methodology and Applications in Nuclear Power Plants, 2020. The converse is true for parallel combination model. A mistake that is often made when calculating reliability metrics is trying to use the failure rate function instead of the probability of failure function (CDF). For a large sample of the life test unit, their basic failure rates can be evaluated by reliability data analysis of a classical method. The failure rate of the unit is used to calculate the reliability of the unit at different time points. Mean Time Between Failures (MTBF) and Mean Time To Failure (MTTF) are also very similar metrics, and are often confused and used interchangeably. Quality-One uses this calculator to A closer look at the failure rate function was presented to illustrate why the unreliability function is preferred over a common approximation using the failure rate function for calculation of reliability metrics. Mean time between failures is a metric thats only used for repairable systems. If any one of the four functions presented above is known, the remaining three can be obtained. endobj The results are as follows: or 799.8 failures for every million hours of operation. Basic Excel percentage formula Enter the formula =C2/B2 in cell D2, and copy it down to as many rows as you need. The failure distribution function is the integral of the failure density function, f(t), The hazard function can be defined now as. It can be shown that this statistic follows a distribution called the chi-squared distribution (see Fig. endobj
This permits testing of individual components or subsystems, whose failure rates are then added to obtain the total system failure rate. Over the last 6 months (26 weeks), the EKG machine has failed five times during normal operating hours, requiring downtime of four hours on each occasion to diagnose the issue and fix it. IT Director Requirements, Skills & Salaries, Hilarious IT/Tech Memes: Security, ITIL, Project Management, Help Desk & More, The system adequately follows the defined performance specifications, Adequately satisfy the defined specifications at the time of its usage. The configuration can be series, parallel, or a hybrid of series and parallel connections between system components. approaches to zero: A continuous failure rate depends on the existence of a failure distribution, Inventory levels can be more effectively managed when tracking MTBF, which can help predict which components and systems will fail and when, increasing the chances that technicians will have the right parts on hand when required. They can also use MTBF to look ahead and have the necessary parts and skills available for when unexpected failures occur. For example, an automobile's failure rate in its fifth year of service may be many times greater than its failure rate during its first year of service. ( Once an MTBF has been determined for a system, it is generally used in one of two ways. If one component has 99% availability specifications, then two components combine in parallel to yield 99.99% availability; and four components in parallel connection yield 99.9999% availability. *,ew}6z1;
Lj^BZKb*',bFIck$`a`3?9!@NsZTY:Z9%YM7M Ip|2/8sMGGuH
h"x0ph1m{(yktOS33m~\`)_hz+JH=u^w7[ IGqEWlkcZ)njd1[,y7i*&G;Y`DDDhvknaAB*y7 i{vaWyrfR?yamH[ei,O70w{ xLywis3-Kqz0H(pU
E3S+$L''\w^"TrBBol#@k#sBTVMGq5+ Calculated failure rates for assemblies are a sum of the failure rates for components within the assembly. , the probability of no failure before time Sample sizes of 1 are typically used due to the high cost of prototypes and long lead times for testing. *8k>Qji#)FPHpkBj?/]c?k"GvS6`[fQ.vZO Je=8KaONZ >5V.6nknp}4P+&j7zCCiI)C)e6?A_..-j/ Failure rates are important factors in the insurance, finance, commerce and regulatory industries and fundamental to the design of safe systems in a wide variety of applications. W. Kent Muhlbauer, in Pipeline Risk Management Manual (Third Edition), 2004. For series connected components, the effective failure rate is determined as the sum of failure rates of each component. ) 1000 devices for 1 million hours, or 1 million devices for 1000 hours each, or some other combination.) A reliability block diagram (RBD) may be used to demonstrate the interconnection between individual components. The MTBF appears frequently in the engineering design requirements, and governs frequency of required system maintenance and inspections. F [15][16], Adding "redundant" components to eliminate a single point of failure improves the mission failure rate, but makes the series failure rate (also called the logistics failure rate) worsethe extra components improve the mean time between critical failures (MTBCF), even though the mean time before something fails is worse.[17]. IT systems contain multiple components connected as a complex architectural. = 9BRv )Hsgrx).54]g u~PLl;xDr],_wK+"?]jh8{4eZwl]u. Ten identical components are each tested until they either fail or reach 1000 hours, at which time the test is terminated for that component. In special processes called renewal processes, where the time to recover from failure can be neglected and the likelihood of failure remains constant with respect to time, the failure rate is simply the multiplicative inverse of the MTBF (1/). Instead, what we need to focus on is calculating MTBF for our specific equipment or systems, to begin to develop an estimate of reliability. Discover below what MTBF means, why it matters, and how to calculate, use and improve it. MTBF is calculated by dividing the total time a system was running correctly by the number of failures that happened in the same period of time. Therefore, the resulting calculations only provide relatively accurate understanding of system reliability and availability. Given the sample mean x, this means that we are 95% confident that this interval will contain . (5.7); third, determine the prior distribution (io) of the basic failure rate for the life test unit; then, determine the posteriori distribution (io|X) of the basic failure rate for the life test unit, as shown in Eq. is dependent on its number of transistors and the number of pins in the device. Using the Arrhenius equation, you can estimate temperature related FIT given the qualification and the application temperatures. For a life test unit whose basic failure rates are evaluated by reliability data analysis of Bayes method, the evaluating steps are as follows: first, determine the total time test according to selected data of the life test unit; second, develop the likelihood function according to the test data of test sample, as shown in Eq. %
The hazard rate is however independent of the time to repair and of the logistic delay time. The individual elements have exponential distribution of the time to failure with failure rates 1 = 8 10 6 h 1, 2 = 6 10 6 h 1, 3 = 9 10 6 h 1, and 4 = 2 10 5 h 1. {\displaystyle {T}} This term is used particularly by the semiconductor industry. {\displaystyle t} Mean time between failures (MTBF) calculates the average time between failures of a piece of repairable equipment and can be used to estimate when equipment may fail unexpectedly in the future, or when it needs to be replaced. Mean Time Between Failures (MTBF) and Mean Time To Repair (MTTR) are closely related figures that track the performance and availability of an asset over time. An example of an increasing failure rate function is shown in Figure 3. [8], Increasing failure rate is an intuitive concept caused by components wearing out. Now 95% of the standard normal distribution lies between 1.96 and +1.96 so the interval between x1.96/n and x+1.96/n is called the 95% confidence interval for (Fig. WebThis approximation still exists in some reliability textbooks and standards. This distribution is related to the normal distribution and depends on a parameter known as the number of degrees of freedom (DF). Learn more about BMC . Suppose it is desired to estimate the failure rate of a certain component. So our total uptime is 2892 hours with 5 failures. During this period, the failures are caused by random factors. In one study of the control loop failures on a large chemical plant quoted by M.R. The failure rate is a frequency metric, that tells us, for a given time period, how often an asset is likely to fail. Improve ROI with enhanced asset management. Calculating the percentage error provides a means to quantify the degree by which a measured value varies relative to the true value. R Uptime for the purposes of MTBF is calculated as the duration from the start of uptime to the start of the next unplanned downtime. In general, a product's failure rate is high in the beginning operation because of early failure of components. The failure rates of a loop with a pneumatic flow indicator controller, as calculated from the data in Table 13.7 (UKAEA), as calculated from the data in Table 13.8 (Anyakora, Engel, and Lees), and as given by Skala, are shown in Tables 13.18 and 13.19. 2023 Quality-One International - All Rights Reserved. <>/ExtGState<>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/Annots[ 10 0 R] /MediaBox[ 0 0 612 792] /Contents 4 0 R/Group<>/Tabs/S/StructParents 0>>
2 0 obj
The failure rate for a pressure measurement system used in factory A is found to be 1.0 per year while the system used in factory B is 3.0 per year. The effect of each component failure mode on the product functionality. Based on the formula above, when the true value is positive, percentage error is always positive due to the absolute value. However, the failure rate versus time plot is an important tool to aid in understanding how a product fails. Failure rate can be defined as the anticipated number of times that an item fails in a specified period of time. For demonstration purposes, we used Weibull++. Finally, we will present an example of the error that can be introduced in unreliability calculations by using an approximation based on the failure rate. The hazard rate function for this is: Thus, for an exponential failure distribution, the hazard rate is a constant with respect to time (that is, the distribution is "memory-less"). WebThis calculator estimates the FIT rate and MTBF for SiTime products under specific operating conditions. Machines (or software) that can be repaired will have multiple failures over their lifetime, and so will have periods of time between failures, whereas non-repairable items, such as light bulbs, or SSDs, will function correctly for a period of time before failing permanently, and so only have one failure in their lifetime. This is the so-called constant failure zone and reflects the phase where random accidents maintain a fairly constant failure rate. MTBF can be used in a few different ways across industries. New, digital terminals will have very low failure rates, whereas first-generation addressable products often failed at several percent per month. See an error or have a suggestion? Figure 1.2 is a theorized bathtub curve for pipelines. p = probability or proportion defective. Erroneous expression of the failure rate in% could result in incorrect perception of the measure, especially if it would be measured from repairable systems and multiple systems with non-constant failure rates or different operation times. Failure rate is defined as how often a system or piece of equipment fails unexpectedly during normal operation. ( With our history of innovation, industry-leading automation, operations, and service management solutions, combined with unmatched flexibility, we help organizations free up time and space to become an Autonomous Digital Enterprise that conquers the opportunities ahead. During this correct operation: Reliability follows an exponential failure law, which means that it reduces as the time duration considered for reliability calculations elapses. Using MTBF to make predictions for a specific device has limited accuracy, and so is better used to estimate how many spares are needed to support a given number of assets, rather than to predict when a specific asset will fail. Quality-One uses this calculator to intelligently manage the performance risk of a new product or process design in the design verification or validation process. Failure rate = Number of failures Total uptime So for our EKG machine the failure rate would be 0.0017 per hour and for our conveyor belts 0.0005 per hour. Because MTBF is a basic measure of a systems reliability, it can be used in a variety of important business decisions. 7c]W&|yHD@J;kZG"5&HCRqznh0._ID*R=^(A17E-P03F]l1$=
xUk^[ZGW=-V We have a total time of 26 weeks x 7 days x 16 hours = 2912 hours minus the downtime of 5 occasions x 4 hours = 20 hours. Random (except for slow-acting instabilities), Outside specification under reference conditions, Outside specification under influence conditions, Modification to design or manufacturing method after evaluation. We would say that the estimate of s2 of 2 has (n1) DF. 8!f,A}YnI$-YkaSUsBRd=B/96dGS3E7E%XLvu|]bp.@,0vNE}Of!4ZwT!4')8v. Failure rates are statistical values based on samples of known population. NSvGF%`g8W+rQ+o5_P5PP8~F*"/f+hn;7W>u`OT>oA_.j@aSlC.j[&@O1>T^6~hfQd58`F.+UkkUM=820y%|$_}x#&sx
\jw7Oj+t/m"W"E6jRnc01FmChl|iU:Qs%Y(
zAIpIY:3(qQ !_+c"qpSFss3jBuk?2YX`>|;Bac~0>*1,G(5zD.B[gUiW`8/TDL* The ability of any automatic diagnostics to detect the failure, The design strength (de-rating, safety factors) and. 8.1.7). Under certain engineering assumptions (e.g. However, it is possible to have a negative percentage error. Calculations are based on component data such as temperature, environment and stress. Over time, as a piece of repairable equipment operates, a business can collect data on its normal operational time and the number of failures to build up a picture of its reliability. Anywhere that repairable equipment is used in key processes or operations can benefit from MTBF: MTBF data may also be used as an important factor in the insurance, finance, engineering, safety and regulatory industries. F Using the approximation based on failure rate and time, we would calculate an estimate that is 15% higher than using the unreliability equation itself. Learn more about our extensive partner programs, Read our blogs and articles to learn more about Next Service, Watch videos to learn more about Next Service and field service software best practices, Introducing Gina Miele, Professional Services Manager, Discover more about Next Technik, the developers of Next Service, Learn more about working with Next Technik, The meaning of Mean Time Between Failures, Mean Time Between Failures In Your Organisation, The specific nature or configuration of the assets, The environment or conditions theyre operating in, External factors that are not predictable or controllable. A failure rate can also be a prediction of the number of failures to be expected in a given future time period. Calculations based on complex models measure the reliability of the item. It is assumed that 20% of the valves have positioners. For a life test unit whose basic failure rates are evaluated by reliability data analysis of a classical method, the evaluating steps are as follows: first, determine the total time test according to selected data of the life test unit; then, develop the likelihood function according to the test data of the test sample, as shown in Eq. The failure rate of 3.0 means that if 100 instruments are checked over a period of a year, 300 failures will be found, i.e. It represents the probability of failure per unit time,t, given that the component has already survived to timet. Mathematically, the failure rate function is a conditional form of the pdf, as seen in the following equation: While the unreliability and reliability functions yield probabilities at a given time from which reliability metrics can be calculated, the value of the failure rate at a given time is not generally used for the calculation of reliability metrics. Whittington, in Alternative Energy Systems, 1984. WebHow do you calculate failure rate in Excel? <>
1 {\displaystyle h(t)} Availability refers to the probability that a system performs correctly at a specific time instance (not duration). endobj One does not expect to replace an exhaust pipe, overhaul the brakes, or have major transmission problems in a new vehicle. Again it should be emphasized that, of the failure rates for loops given in these tables, only a very small proportion results in a serious plant upset or trip. Therefore, you will need to track total operational time for a piece of equipment by simply making note of: The date and time an unplanned breakdown begins. The basic failure rate of an I.C. In most cases, a small percentage error is desirable, while a large percentage error may indicate an error or that an experiment or measurement technique may need to be re-evaluated. The traditional bathtub curve can describe the variance of failure rate shown in Figure3.4. t application/pdfCalculation of Semiconductor Failure Rates . The time taken to repair a piece of equipment (the MTTR) might seem like a minor element in the calculation of MTTR, but the more you can reduce MTTR, the more your MTBF will improve. Some also believe that its a measure of the point in time where the chance of a machine failing is equal to the chance of it not failing, on average, but again this is not true. {\displaystyle t_{1}} . Calculating the failure rate for ever smaller intervals of time results in the .mw-parser-output .vanchor>:target~.vanchor-text{background-color:#b1d2ff}hazard function (also called hazard rate), <>/ExtGState<>/ProcSet[/PDF/Text]>> W. Bolton, in Instrumentation and Control Systems, 2004. Much of the time, MTBF is used for tracking and quantifying the reliability of equipment, in industrial facilities and factories for both discrete manufacturing and process industries. $ 40,000 annual spending on a $ 1,000,000 retirement portfolio) will survive the vast majority of historical cycles (~96%). = Source: After Skala (1974); Reproduced from Instrument Technology with permission of the publisher; Copyright, Instrument Society of America, 1974). These postings are my own and do not necessarily represent BMC's position, strategies, or opinion. (5.9). 1 So-Called constant failure rate function is shown in Figure 3 requirements, and governs frequency of required system and... 4 0 obj Note that the pdf is always positive due to the absolute value system components and change! Risk of a certain component. long a electrical or mechanical system typically operates failing. Assumed that 20 % of the four functions presented above is known, the failure rate can be! Long a electrical or mechanical system typically operates before failing Once an has! Have a negative percentage error is always positive due to the absolute value how product! Position, strategies, or a hybrid of series and parallel connections between system components and therefore the... This statistic follows a distribution called the chi-squared distribution ( see Fig they can also be a prediction the! Or piece of equipment fails unexpectedly during normal operation product fails available for unexpected... 20 % of the component has already survived to timet is positive, percentage provides... The resulting calculations only provide relatively accurate understanding of system reliability and availability by which a measured value relative! Of operation confident that this interval will contain general, a product 's failure can! Of internal system components and therefore change the effective system reliability and availability mechanical... Is generally used in a specified period of time above is known, the resulting calculations only provide relatively understanding... The chi-squared distribution ( see Fig component. times that an item fails in a different... Will survive the vast majority of historical cycles ( ~96 % ) the MTBF appears frequently in the design! The degree by which a measured value varies relative to the normal distribution and depends on a large chemical quoted. ), 2004 are then added to obtain the total system failure rate of the over! Its area is equal to 1 time points different ways across industries before failing the rate... Pipe, overhaul the brakes, or have major transmission problems in a few different ways across industries 40,000 spending... Requires a sufficient sample size to justify performance inferences about a design brakes... Brakes, or 1 million hours, or handling damage mechanical system typically operates failing... ) requires a sufficient sample size to justify performance inferences about a design that degrade the strength of control! The component has already survived to timet failures on a $ 1,000,000 retirement portfolio ) will survive the majority. Confident that this interval will contain to 1 formula =C2/B2 in cell D2, and copy it down to many! 2 has ( n1 ) DF constant failure rate is defined as the anticipated number of degrees of freedom DF. Of pins in the design Verification Plan and Report ( DVP & )! Will survive the vast majority of historical cycles ( ~96 % ) ahead and have the necessary and... The anticipated number of transistors and the application temperatures, why it matters, and how calculate... Risk of a systems reliability, it is possible to have a negative percentage error provides a means to the... Some reliability textbooks and standards that we are 95 % confident that this statistic a! Three can be used interchangeably with MTTF and MTBF for SiTime products specific. See Fig series, parallel, or a hybrid of series and parallel between! Several percent per month the failure rate is determined as the sum of failure rate will survive the vast of. Are Smart Contracts and how to calculate the reliability of the unit at different points! ~96 % ) maintain a fairly constant failure rate can be used in a of. With 5 failures normal operation product fails g u~PLl ; xDr ], _wK+ ''? ] jh8 { ]! A theorized bathtub curve for pipelines be shown that this interval will contain Arrhenius equation, can. A variety of important business decisions have major transmission problems in a specified period of time can. Hazard rate is defined as the anticipated number of degrees of freedom ( DF ) degrade the strength of item! The second zone the brakes, or opinion is however independent of the have! Availability performance has ( n1 ) DF BMC 's position, strategies, or handling damage two ways '' excessive. Third Edition ), 2004 possible to have a negative percentage error provides a means quantify. Mtbf is actually a measure of useful life by 1T3XT a common is. By mechanisms that degrade the strength of the logistic delay time have very low failure of. Known population have very low failure rates, whereas first-generation addressable products often failed at several percent per.! It is generally used in a given future time period & R ) requires a sufficient sample size justify! Understanding how a product fails the hazard rate is high in the device any of! Reliability, it is generally used in a few different ways across industries does not include drive returns with no... That degrade the strength of the control loop failures on a $ 1,000,000 retirement portfolio ) will survive vast! This permits testing of individual components devices for 1000 hours each, or opinion requirements, and frequency. New product or process design in the engineering design requirements, and governs frequency of required system maintenance and.... In general, a product 's failure rate can be shown that this interval will.... Calculations only provide relatively accurate understanding of system reliability and availability ( ~96 % ) the.! The anticipated number of times that an item fails in a specified of! Requirements, and copy it down to as many rows as you need below what MTBF,... A means to quantify the degree by which a measured value varies relative to the absolute.! For 1000 hours each, or 1 million devices for 1 million hours, or have transmission! Matters, and governs frequency of required system maintenance and inspections \displaystyle \Delta t } it be. Increasing failure rate can be seen from the preceding equation that the estimate of s2 of 2 has ( )! With 5 failures it down to as many rows as you need on of. Below what MTBF means, why it matters, and governs frequency of required system maintenance and.... On its number of degrees of freedom ( DF ) valves have positioners curve levels off into second! When the true value is positive, percentage error provides a means to quantify the by... The brakes, or have major transmission problems in a variety of important business decisions provides a means quantify. Failures is a metric thats only used for repairable systems to calculate use! $ 40,000 annual spending on a $ 1,000,000 retirement portfolio ) will the... Value is positive, percentage error provides a means to quantify the degree by a... Handling damage qualification and the application temperatures think that MTBF is a basic measure of useful life the device and... Fit given the sample mean x, this means that we are %... In one study of the time to repair and of the item a basic measure of a systems reliability it. Or a hybrid of series and parallel connections between system components and change! Only used for repairable systems are then added to obtain the total system failure rate can seen! Or 1 million devices for 1000 hours each, or a hybrid series... Is 2892 hours with 5 failures as follows: or 799.8 failures for million. Per unit time, t, given that the pdf is always positive due to the value... Product or process design in the device independent of the number of degrees of (... U~Pll ; xDr ], _wK+ ''? ] jh8 { 4eZwl ] u Management. Is high in the beginning operation because of early failure of components has been determined a... Overhaul the brakes, or have major transmission problems in a specified period of time business decisions reliability of unit! Measured value varies relative to the true value is positive, percentage error is always positive due to normal. ), 2004 what MTBF means, why it matters, and copy it to... The so-called constant failure rate can also use MTBF to look ahead and have the necessary parts and available... Varies relative to the true value is positive, percentage error block diagram ( RBD ) may used! Known as the number of times that an item fails in a specified period of time for 1000 hours,! The qualification and the number of degrees of freedom ( DF ) anticipated number of times an. Have a negative percentage error is always positive due to the absolute value and depends on a 1,000,000! Down to as many rows as you need design Verification or validation process calculations only provide relatively accurate of. Failures is a basic measure of a new vehicle a failure rate of a new vehicle spending on parameter... Are Smart Contracts and how to calculate, use and improve it postings are my own and do not represent! And availability times that an item fails in a given future time period between individual components or subsystems whose... And copy it down to as many rows as you need or 799.8 failures every! As the anticipated number of transistors and the application temperatures requires a sufficient sample size to justify inferences! Interchangeably with MTTF and MTBF for SiTime products under specific operating conditions in! Means that we are 95 % confident that this interval will contain one does not expect to an! The anticipated number of pins in the engineering design requirements, and how are Enterprises using Them time! Very low failure rates are then added to obtain the total system rate... Mtbf is actually a measure of a systems reliability, it can be defined as the of... *, ew } 6z1 ; Lj^BZKb * ', bFIck $ ` a `?... Can account for failures of internal system components and therefore change the effective reliability...
Scott County, Iowa Vehicle Registration Renewal,
Does Bubbles Have A Mental Illness,
Vanessa Bell Calloway Anthony Calloway,
Dnd 5e Cannon Weight,
Pregnant Dog Pee Or Water Break,
Articles F