Соnditiоn Monitoring and Fault Diagnosis Essay Example

Соnditiоn Monitoring and Fault Diagnosis 4


Failure in monitoring machinery can lead to their failure. It is monitoring that aids in decisions whether to rotate a machine, repair or replace them depending on what has been detected. Some machines are vital to the operation of an organization and, therefore, should always be kept functioning. A water cooling system for this case is a very crucial system in the maintenance of other machinery that works within its environment.

With the use of machine maintenance methodology which is predictive such as vibration monitoring, conditions of impending failures in a system can be predicted earlier enough and necessary actions such as rotation of the machinery taken. With the help of these predictive machines, conditions such as catastrophic failures can be reduced, increase the life of machinery apart from reducing the cost of maintenance for vital machinery.

In the design of a water cooling system, the materials to be used should be those that are not good in oxidation like copper or brass since water is a very good oxidant. Also bearing in mind that it is a cooling system and a lot of heat is involved, the material should also be that which has a good thermal conductivity[ CITATION Kim03 l 1033 ].

Vibration analysis which always a common method of monitoring rotating systems or parts of these systems is one of the most commonly used methods of monitoring technology. Most vibration machines today use Fast Fourier Transform technology where vibration signals from the sensor for a given period of time are converted into a frequency domain which is easy to present and analyze. This technique is known as vibration signature analysis or spectral vibration analysis. A water cooling system would have an accelerometer which will be directly attached to a vibration meter to assist in measuring the output power of the system[ CITATION Raj03 l 1033 ]. The readings from the accelerometer can be recorded and kept in a database and the statistics used in assessing the pump. There should be a limit set on the pump that when it passes or approaches, the mechanics may be in apposition to tell that the machine is approaching a danger zone, and appropriate action be taken which may include rotation. Vibration monitors should be placed around parts of the system that rotate such as pumps, fans and motors in their bearings at 90 degrees rotation to capture both horizontal and vertical acceleration of these rotating parts[ CITATION MaZ08 l 1033 ].

Advantages and Disadvantages of Vibration Sensors

The advantage that comes in hand with vibration sensing is that monitoring periods can be increased without incurring additional costs hence giving space for improved fault detection. However, in the case of failure of these detectors, the costs for their replacement are very high. Another disadvantage is that these vibration detectors stainless steel bodies which are resistant to water to rest on which are expensive to acquire and maintain having in mind that they are working on the water environment and are sensitive to both heat and other fluids apart from water. A vibration detector at times may mistake sound waves for a vibration thereby leading to incorrect reading. This is one of the disadvantages of using a vibration detector[ CITATION Kus97 l 1033 ].

Advantages and Disadvantages of a Sound Analyzer

The advantage of the sound analyzer is that it has the ability to capture non-repetitive events. It also has the ability to analyze sound signal phase on its own. However, its disadvantage is that it has a set frequency limit which it cannot capture signals beyond. It is also very costly to purchase

Advantages and Disadvantages of Temperature Sensors

The advantage of temperature sensors compared to other condition sensors is that they are rather cheap and have a higher degree of stability on average conditions. However, the disadvantage is that most become unstable when used in areas with extreme temperatures. A universal disadvantage of these monitoring systems is that they are electronic devices which are known to be very sensitive to oil, water, and high temperature[ CITATION Kus97 l 1033 ]. Water can make them short circuit, and oil can lead to the incorrect measurement from devices like those which monitor temperature because some oils have a tendency of absorbing heat.

From the data in the tables, there seems to be a sense of consistency which implies a good and healthy condition for the equipment. If at be beginning of, week one the readings could be high then down the line the readings get smaller; there could be a suspected fault in the equipment. My comment for the data in the tables is that it shows consistency, and it is a sign of healthy functioning of the equipment.

Graphs for average vibration (mm/s) against time (weeks) are as shown below:

Condition monitoring and fault diagnosis

Condition monitoring and fault diagnosis  1

Graphs for temperature (Celsius) against time (weeks) are as shown below:

Condition monitoring and fault diagnosis  2

Condition monitoring and fault diagnosis  3

Condition monitoring and fault diagnosis  4

Online condition monitoring method involves continuous and cyclic monitoring of the entire system and processes the data collected immediately, and the monitoring device is attached to the machine while an offline method is that which is time based or periodic and can be removed out of the system.

Advantages of Online Monitoring Processes

Using an online monitoring system, it detection in failures can be done earlier enough before they harm since the monitoring system is always with the machine

It is easy to follow the data trend for the machine since the data is only from that particular device[ CITATION Pan09 l 1033 ].

Disadvantages of an Online Monitoring System

The permanency nature of the monitoring system makes it be used only on one machine. Failures in the monitoring system might be hard to notice due to less interaction with the system due to its permanent nature. Online monitoring systems are subjected to risks which may be due to those associated with leakage and fire hence their high probability of failure[ CITATION Pan09 l 1033 ].

Advantages of an Offline Monitoring System

Their temporal nature makes them easy to be used on more than one machine.

Failures on offline monitoring systems are easy to detect since the system engineer usually interacts with them. They are less subjected to risks such as fire and those from accidents like leakage, hence making their lifespan longer than the online monitoring systems[ CITATION MaZ08 l 1033 ].

Disadvantages of Offline Monitoring Systems

It is hard to determine data trend for one machine when using an offline monitoring system since it is used for more than one machine and only attached to the system when the readings are being taken[ CITATION MaZ08 l 1033 ]. On offline monitoring system is more subjected to fraud and misuse due to it flexible nature than an online management system.

Alternative Maintenance Strategies

A run to failure maintenance strategy is where maintenance is only carried out when a piece of equipment fails. This maintenance strategy aims at reducing the total maintenance cost, unlike preventive maintenance strategy. Run to failure maintenance strategy can be adopted where preventive maintenance is not easy, like when the equipment to be maintained is located in a place that is not easily reachable which may be a confined place or a remote location. This maintenance strategy can lead to a standstill of the organization processes if the failure occurs on critical machinery, for example, the power supply like a generator[ CITATION Kru141 l 1033 ].

Other maintenance strategies may include fault diagnosis where there is the use of historical data and the behavior of a system that is still functioning to foresee damage and necessary repair schedules are put in place, so that in case a fault occurs, there is an immediate action taken for it.

Another method might be a measurement in containment. This is a technique of monitoring machinery or machinery parts in a room where the environment has no bias. These rooms are free from contaminations for any instrumentation used making them conducive. Examples of machines that can be tested using this technique include the mortar, fans, and pumps[ CITATION Kus97 l 1033 ].

The next maintenance strategy is trend analysis which is a method of using the past and the current data from the system to make a schedule for a possible future breakdown. Trend analysis uses the data at extreme ends of the machine operation. These kinds of data may be those from the least expected reading and the highest from the machine producers.

Low equipment criticality is a method in relation to failure maintenance strategy where an equipment which fails cannot cause a threat to lives or has no significant contribution to an organization’s profit can be considered to be maintained when it fails. An example can be a gate bulb[ CITATION Raj03 l 1033 ]. You only replace the bulb when it blows out.

Vibration Monitoring

Vibration monitors can be attached to a cooling water system on its base using magnetic adapters for temporary installation on portable systems and also using quick fit adapter where permanency is needed. Vibration monitors attached to rotating parts receive vibration signals from time to time converting them to wave domain for presentation. The signals can tell be as a result of lack or inadequacy of lubricants on the bearings, misalignment and even looseness of the system part. Depending on the analysis of the waves, the system engineer is in a position to tell the condition of the part this device is attached to and devise an appropriate plan for repair or rotation in case of a suspected defect.

Temperature Monitoring

Heat detectors are also fitted in around moving parts because these parts are associated with friction and friction also relate to heat. A Large amount of heat can lead to the breakdown of electronic devices and also high temperatures are known to be uneconomical when it comes to power consumption; therefore, heat detectors are necessary. The role of a temperature monitor is to check the amount of temperature and take a necessary action depending on the amount. If the temperature is too low, it raises it to the required amount. If the temperature is too high, it provides a cooling mechanism. A cooler consists of three primary components which are an evaporator, condenser, and a compressor. When the temperature increases, a water cooler will act as follows. The water will be evaporated; the evaporated water being in the gaseous state will be compressed and turned back to liquid. In the process, the heat is lost, and the cooling effect is achieved. When the temperature drops below normal, the sensors will detect it. The evaporator will provide a heating sensation that will see the temperature rise to the required amount.

Leak Detectors

This detector is used in systems that contain gasses and liquid to determine whether a leak has occurred. The main method used by these detectors is the hydraulic test. This testing technique involves determining pressure loss in closed systems. The gas or the liquid supply valves are closed and also the outlet valves for a suspected system the observation is made whether the pressure is steady or whether there is a decrease. If there is a decrease in pressure, it means that the system is leaking, and necessary repair or replacement can be made before other expenses are incurred. For a water cooling system, the leak can reduce the water pressure leading to a long period of cooling phase bearing in mind that the higher the pressure, the higher the rate of condensation hence the higher the rate of cooling.

Detecting Corrosion and Cracks

Corrosion and cracks can sometimes occur due to acidity, wear and tear of some machine parts due to poor maintenance or high pressure; therefore, it is necessary to put controls to this. Through the use of leak detectors, the engineer is able to tell the occurrence of both cracks and corrosion however it is advisable that regular checkups be done to the system apart from using the control systems to ensure that moving parts are properly greased, and there is no leaking part that might lead to corrosion.

Commercially Available Sensors

An example of a commercial pressure sensor is BMP180 Breakout, which is a barometric pressure sensor. It measure the pressure of the air around and then the data collected from it is transferred to an external microcomputer which runs a software knows as Arduino which is available for both Windows and Macintosh operating systems.

An example of a leak detector is FroLogic, which made in the USA. This leak detector is used in homes do prevent the abnormal flow of water from damaged pipes. It uses circuit breaker technology and automatically cuts the power supply to the water source preventing further flows which could cause damage. This system is available in versions for commercial buildings and for residential.

An example of temperature monitoring system is the TempTrak from TempTrak Enterprise. It is a wireless monitoring system that uses a special hardware with is software installed to monitor temperature. It also has an additional hardware for storing temperature data.

Reference List

Kim, J. K. & Smith, R., 2003. Automated retrofit design of cooling-water systems. AICHE Journal, 49(7), pp. 1712-1730.

Krupenko, L. S. & Kapelush, N. V., 2014. Condition of assimilation system tilia cordata under aerogenic pollution in Zaporozhye City. Питання біоіндикації та екології, 19(2), pp. 84-90.

Kusnetsov , J. M., Tulkki, A. I., Ahonen, H. E. & Martikainen, P. J., 1997. Efficacy of three prevention strategies against legionella in cooling water systems. Journal of Applied Microbiology, 82(6), pp. 763-768.

Ma, Z., Wang, S., Xu, X. & Xiao, F., 2008. A supervisory control strategy for building cooling water systems for practical and real time applications. Energy Conversion and Management, 49(8), pp. 2324-2336.

Panjeshahi, M. H., Ataei, A., Gharaie, M. & Parand, R., 2009. Optimum design of cooling water systems for energy and water conservation. Chemical Engineering Research and Design, 87(2), pp. 200-209.

Rajagopal, S., Van der Velde, G., Van der Gaag, M. & Jenner, H. A., 2003. How effective is intermittent chlorination to control adult mussel fouling in cooling water systems?. Water Research, 37(2), pp. 329-338.