Calculating Production Reliability for Two 60% Capacity Compressors in Parallel

Question:

Hello Expert, I am seeking your guidance on calculating the reliability of a machine. Within the manual, a scenario is described where two 60% capacity machines run in parallel, allowing the process plant to operate smoothly even if one compressor fails. While theoretically the overall mechanical reliability of such a system would be 81% with individual machine reliabilities at 90%, a simple calculation may be misleading as production would be reduced to 60% capacity when one unit is down. Therefore, the actual production reliability of this setup is approximately 92%. I am curious how this 92% production reliability is determined. Your insights are greatly appreciated. Best regards,

Top Replies

Which user guide is being referred to?

Hey there! That's an intriguing matter you've raised. The 92% production reliability is likely calculated by assuming that only one machine will fail at a time. In such cases, we would have at least 60% production capacity available from the secondary machine. Now, if you think about it, if a machine is running 90% of the time (which is its reliability), it's down 10% of the time. Therefore, the 10% downtime would be running at 60% capacity. Essentially, 10% of the time, you have 60% production, which amounts to 6%. So, if we add this 6% to the 90% of uptime when both machines are in play, we get a total of 96% production reliability. However, upon considering factors like the time it takes to switch to the secondary machine and the possibility of both machines breaking down simultaneously, it seems that the manual may have rounded down the reliability to 92%, which indeed sounds about right.

Hi there! It seems like you're referring to the availability (also referred to as production reliability). In the case of two 60% capacity machines running in parallel, the concept of 'redundancy' comes into play. Even if one machine fails, the second steps in to continue operation. This type of system design increases the reliability on a production level. The 92% reliability in production likely accounts for the overlapping operational capability with the redundant system. Think about it this way: if you have backups or alternatives in place, the chance of having a complete shutdown is reduced, hence the higher reliability percentage compared with individual machinery. However, for a more specific breakdown and to assure this is the method they used, you might need more detailed information about their computation methods underlying that 92% figure. I hope this helps!

Hi there, it's indeed a complex calculation but the idea here is to map out all the scenarios that can occur. Let's say machine A runs successfully 90% of the time and fails 10% of the time. It's similar for machine B. When A fails, B with its 60% capacity will be operating 90% of the time allowing 54% (0.6*0.9) production, and it will fail 10% times causing production to halt. This way, we get 90% successful run and 4% halted production when A fails. With the same principle, when A operates, B may or may not fail but A will still provide 90% capacity. Add them up altogether and that figures out to be 92%. Even though the system seems to have 81% mechanical reliability, technically the production reliability is some 92% considering all possible cases. Hope this makes sense!

Hi there! It seems like you've delved into a fascinating area of reliability engineering. The 92% production reliability is likely derived from a concept known as 'system reliability' in the context of parallel systems. Essentially, when the two machines are operating in parallel, there's only a 10% chance (100% - 90%) that either will fail. Now, for the system as a whole to fail (i.e., for production to drop below 60%), both machines would have to fail simultaneously. So, the chance of this happening is 0.1 (chance one fails) * 0.1 (chance the other fails) = 0.01 or 1%. So, the system reliability, or the chance the system does not fail, is 1 - 0.01 = 0.99 or 99%. This 99% system reliability is higher than the original 90% reliability of the individual machines because you have redundancy built into the system. Now, if we account for the fact that each machine can only run at 60% capacity, the actual production reliability becomes 0.99 (system reliability) * 0.6 (capacity of one machine) = 0.594 or 59.4% for each machine. Then, since you have two machines, your total production reliability is 0.594 * 2 = 1.188 or approximately 92% when rounded to the nearest whole number. It's also important to note that this is a simplification and actual industrial scenarios may involve more complex calculations and considerations.

That’s a great question! The 92% production reliability comes from considering not only the individual machine reliabilities but also how the combined system functions under load. When one machine fails, the other takes over, but since both machines only operate at 60% capacity, when one goes down, you’re still left with that maximum output of 60% from the working machine. The 92% figure likely reflects the uptime calculations based on the probability of both machines working together, adjusted for expected production capacity instead of just mechanical reliability percentages. Essentially, it balances the reliability of the machines with the operational impact of any failures.

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Frequently Asked Questions (FAQ)

FAQ: 1. How is production reliability calculated for two 60% capacity compressors running in parallel?

Answer: - The production reliability for this setup is determined by considering the impact of having one compressor down on the overall production capacity. In this case, even though each compressor has a reliability of 90%, the system's production reliability is approximately 92% due to the reduced capacity when one unit is not functioning.

FAQ: 2. Why is the actual production reliability higher than the individual machine reliabilities in this scenario?

Answer: - The actual production reliability is higher than the individual machine reliabilities because the setup involves two machines running in parallel at 60% capacity each. This redundancy allows the process plant to continue operating at a reduced capacity (60%) even if one compressor fails, resulting in a higher overall production reliability of approximately 92%.

FAQ: 3. What factors should be considered when calculating production reliability for parallel machines?

Answer: - When calculating production reliability for parallel machines, it is important to consider the impact of machine failures on overall production capacity, the redundancy provided by having multiple machines, and how the system responds to failures to maintain operation. These factors can influence the actual production reliability of the setup.

FAQ: 4. How can a simple calculation be misleading when determining the reliability of machines running in parallel?

Answer: - A simple calculation may be misleading when determining the reliability of machines running in parallel because it may not account for the impact of machine failures on overall production capacity. In the case of two

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