Engineering System Safety Report about Microwave Oven - Book Report/Review Example

of Lecturer] Engineering System Safety Report about Microwave Oven Executive Summary Microwave ovenis one of the modern day household appliances that make life easier, faster and more convenient for humans. However, being an electromechanical appliance, its ownership and use is accompanied by many health and operational hazards. Through safety analysis, these risks and health hazards associated with the use, ownership, closeness to microwave oven can be identified then the right barriers and mitigation measures established. This paper details the findings of various analyses conducted on microwave oven and gives recommendations and conclusions that are instrumental in the operationalisation, storage and maintenance of the appliance. Importantly, through the analysis report, operators and those close to the appliance are informed on how to care for their health so that they are not physiological, psychological and physical harmed by the appliance’s many health hazards. Evidently, if used well, with strict adherence to manufacturer instructions on usage and maintenance, microwave oven is one of the electromechanical appliances than can make a person’s life more comfortable and convenient. Introduction More and more families are acquiring modern and complex household electronic and electrical gadgets to make their lives easier and more comfortable (Ericson, p. 23). Because of the busy life and the need to do things faster, electronic and electrical items businesses continue to boom by the day (Juran & Frank, p. 21). An example of the electronic and electrical gadgets that have become common in homes in recent times is the microwave oven. Due to its nature and the process by which it heats food, microwave oven use has been shrouded in many controversies, especially with regards to its health hazards and risks. These risks are psychological, physical and physiological. This paper conducts a hazards analysis of the microwave oven. Before conducting a preliminary hazard analysis, a list of some of the risks associated with the microwave oven is given. Then, a hazard analysis of its support and operating systems will be conducted followed by a failure mode and effect analysis. Finally, barrier, health hazard assessment and fault tree analysis will be conducted. Diagram 1: the general parts of microwave oven Microwave oven is used in heating and cooking and it uses shortwave electromagnetic energy, which move at the speed of light. This radiation from the device interacts with food or water molecules as the positive and negative ends of these waves interact with the positive and negative ends of water and food molecules. The high-watt alternating current in microwave ovens interact with and bombard food molecules, which then rotate at rates of millions of times per second. This agitation of food and water molecules results in friction. The friction heats the food and damages its molecules, a process referred to as structural isomerism. In its basic formation and functioning, a microwave oven is made of mechanical devices and electrical circuits, which functioned in a combined and coordinated manner to produce controlled energy in the form of microwave. Microwave oven is used for heating and cooking. A microwave oven has control and high-voltage sections. The former section regulates the system’s power output. This section is composed of an electronic timer in addition to other protection and interlocking devices. As its name suggests, the high-voltage section is used to step up the output of the system to high voltage. This high voltage is changed into microwave energy. The working of the microwave oven starts when electricity from the socket outlets moves to the gadget’s power cables, fuses, protection circuits, which turns off the gadget in case of overheating. Under normal heating, the electric power goes through the timer and interlock circuits. With the oven door closed, electric path is established via the interlock switches. When the oven timer is set and the cooking operations started, the voltage established is extended to the control circuit, which has an electromechanical relay system known as the triac. The diagram below summarises the parts and the functioning of a microwave oven. Diagram 1; showing the parts and the functioning of a microwave oven Methodology The use of microwave oven has been surrounded by many controversies related to health hazards and their effects on human life and well being. Hence, quite many studies have been conducted to analyse the extent to which the operating and support systems of a microwave oven endanger human life and well-being. To assess and analyse the risks and hazards to the microwave oven, this study applied different approaches to the analysis. First, a quick literature review was conducted to give a basic idea on the components and the principles and procedures of the microwave oven. In the analysis of the risks and health hazards of the system, a preliminary list of its risks and hazards was developed. Second, a preliminary analysis of the system’s hazards was done. The third phase of the analysis targeted the microwave oven operating and support system. The fourth analysis done was the assessment of the health hazards associated with the device. The study also entailed a fault tree analysis, failure mode and effect analysis as well as a barrier analysis. Diagram 2: a schematic presentation of microwave oven Preliminary List of Hazards This section lists some of the hazards associated with microwave oven usage for heating and cooking. 1. Monitoring system failure to interlock switch status 2. Broken door latches 3. Timer failures 4. Damages and leakages to the door 5. Malfunctioning thermal protector 6. Prtially discharging capacitor 7. Magnetron malfunction/failure 8. Malfunctional thermal fuse 9. Faulty triac 10. Exceedingly high voltage Preliminary Hazard Analysis In the preliminary hazard analysis revealed that a microwave oven may have a damaged glass door, which may expose the operator and others around the gadget to harmful radiation and heat from the oven. Second, the preliminary analysis identified a failure in the monitoring system of the device as potentially harmful as it may damage the electric circuit and cause leakages of heat and radiation, thus harming the operator. System: Microwave Oven Analysis: Preliminary Hazard Analyst:………………………………………………………………… Date:……………… Preliminary Hazard Causes Effects Comment 1 Monitoring system failure to interlock switch status Manufacture defect; design error; poor connections of interlocks and the monitoring system Electric circuit damages and leakage; serious injury Top-level mishap (TLM) 2 Broken door latches Factory defects; substandard materials; design errors; operator accidents Electromagnetic leakages, adverse health and environmental effects TLM 3 Timer failures System failures Possible explosion and fire TLM 4 Damages and leakages to the door Misuse/poor handling, poor quality appliance, factory defects High-energy electromagnetic radiation may leake to the environment, causing injuries to the environment TLM 5 Thermal protector fails to deactivate in case of overheating System/control panel failure Possible explosion and fire TLM 6 Partially discharging capacitor Faulty high-voltage transformer Machine damage and electric shock TLM 7 Magnetron failure/malfunction Faulty/defective magnetron Excessive microwaves, microwave leakages, injuries to the operator and the environment TLM 8 Faulty triac Factory errors, defects, non-conformance to safety requirements, sub-standard appliance Leakage of harmful microwaves, harm to the environment, machine damages TLM 9 Malfunctioning thermal fuse Electric system/circuit failures Explosion, fire, injuries to health TLM 10 Exceedingly high voltage Faulty high-voltage transformer Machine damage, health injuries to the operator, possible death TLM Operating and Support Health Analysis There are numerous hazards or risks associated with the operation of the microwave oven. The table below summarises these hazards or risks, their causes, mitigation measures and their effects on the devise as well as the user. System: Microwave Oven Analysis: Preliminary Hazard Analyst:………………………………………………………………… Date:……………… Operation area Risk/Hazard Causes Effects Mitigation Measures 1 Monitoring Failure of monitoring system Poor connections, design or manufacture errors Injuries to the user because of electric leakage Routine inspection of system and connections of interlocks 2 Operating the device Broken interlock switches Damaged switches Current passes to the control circuit even when the door is open Use of multiple interlock switches, use of quality parts for the switches 3 Power gush Faults in the wiring system Could damage the device Inspection and installation of power surge-protection devices 5 Failure of thermal protector Wear and tear of parts and substandard parts System overheating Use of quality device and parts 6 Manufacturer or design defects, wear and tear Interruption of current flow, impaired operations Quality device, routine inspection Health Hazard Assessment The microwave oven is associated with numerous health hazards, especially to the use and those within the vicinity of the device. These categories of people are not only exposed to the electromagnetic radiation and heat from the device but also face danger from spilling of the device’s contents. They are also exposed to dangers arising from accidents such as the device exploding. Microwave health hazards originate from shock, radiation, extremely high temperatures and chemical substances from which it is made. The operator of the device should therefore be aware of these hazards and establish effective mitigation measures to prevent their occurrence. Health Hazard source Causes Effects Mitigation measures Explosion of food/ water being heated High microwave temperatures Poor handling of the device, not following manufacture instructions Scalds, burns Setting the right heat level, locking the door, allowing cool-down Electric shock High voltage discharge Exposure to parts of device that carry electric power Serious injuries, electrocution Use of electric shock or ‘danger’ warnings Exposure to damaging radiation from the device Leakage of electromagnetic radiation from the device Poor insulation of the device, faulty doors and hinges and unlocked door Increased risks of ancerous cells or growths Proper installation and use of quality doors, latches and hinges Exposure to harmful oven elements Metallic components of the device Contact with harmful components due to ignorance or accidents Damage to skin, fire, inhalation o and contact with toxic elements Adherence to manufacturer safety instructions Barrier Analysis It is equally of the essence to assess the barriers or mechanisms and gadgets by which an operator of the microwave oven can protect himself or herself from the identified risks and hazards of using or owning the device. The table below summarises the identified gadget and operator barriers, which would be quite effective in protection and minimisation of the risks and hazards associated with the device. Operator/device Barrier Hazard prevented Causes and sources of hazard Operator Hand gloves Burns and scalds from the device and hot food Careless handling of food and hot points of the device Device and operator Warning/danger notices Explosion of overheated food/water, causing burns and scalds Overheating food/water, extremely hot metal containers Device and operator Isolations and insulation High-voltage shock and death from transformer Interaction with high-voltage from malfunctioning transformers operator Insulation of equipment Exposure to harmful electromagnetic radiation Prolonged exposure to high-energy/voltage electromagnetic radiation from the oven Failure Mode and Effect Analysis Just like other electromechanical devices, the microwave oven is prone to many types of failure, which may render it ineffective or harmful to the operator and other living things around it. Hence, a failure mode and effect analysis of the gadget is essential. The components of the device prone to failure are timer circuits, thermal protectors, the magnetron, power input and output controllers, the monitoring system, the interlock switch, the door, hinges and the electric circuit. These failures have their causative factors and effects. Thus, the operator should prevent and detect these failures in a timely manner whenever they occur. Nonetheless, there are set controls that operators should learn from the manufacturers’ instruction as well as from experience (Michalsky, p. 34). The table below summarises the commonest microwave oven failure modes and their effects. Failure Mode Effects Causes Detection Control Mitigation Damaged doors/hinges/latches Poorly locked door, exposure to heat and non-ionizing radiation Poor installation, defects from the manufacturer Device should be inspected on purchase and as a routine Ensure the nuts and locks are fasted Quality locking devices and materials -notices for users to lock door properly Faulty, broken or worn out interlock switch Current exceeds safety levels Broken switch, defects, poor current flow Use of failure detection switch Failure detection switch Maintenance and use of quality parts Faulty thermal protector, which then malfunctions Overheating cannot be quickly detected Friction and breakage, poor quality parts Initial and routine inspection Monitoring of gadget quality and operationalisation Purchase and use of standard and recommended devices and spare parts Timer circuits malfunction Interference with current flow, time wastage Poor design and quality, short circuit Use of alarm Quality monitoring and evaluation after use Maintenance and quality devices and spare parts Faulty monitoring system Unsafe and erroneous operation Design and manufacture defects/errors, poor device connections Via the control circuit Control circuit Following manufacturer instruction, proper connections Discussions, Conclusions and Recommendations As the safety analysis has revealed, microwave oven use is marred by quite many health hazards and risks. Consequently, the operator of the device should take utmost care while using or handling it in anyway. The first and most important recommendation for preventing and addressing the safety issues of microwave oven is to leave all the repair of electronic parts of microwave oven to a professional. Notwithstanding its small size, the device has the capacity to store high volts of electricity in its capacitor. This voltage is equally dangerous when the device has been unplugged from the source of electricity. Thus, the replacement of worn out or malfunctioning parts of the device could be quite dangerous for non-professionals. Cleanliness is also of importance in the maintenance of the device and its safety. In fact, the inside of the gadget should be cleaned more frequently. Since food particles and splatters normally absorb some of the microwave energy while the microwave oven in operational, it is advisable to clean the inside of the gadget using a microwave oven cleaner. The other microwave safety and protection strategy is to close the door carefully, taking care not to slam it. The three switches of the latch mechanism should also be closed in the set order. Notably, slamming the door could interfere with this sequence. The operator should also use the preset cooking time to promote the effective heating of the food. In addition, the device should not be run empty since empty running may damage it. When there is no food in the switched on gadget, the microwave energy bounces back and forth inside since it is not absorbed. This bouncing results in the magnetron overheating and failing. Clearly, the overheating makes it more costly, in terms of energy wastage and costly repairs. Of greatest importance in the maintenance and safety of a microwave oven is the avoidance of surge damage. The operator is advised to plug the microwave oven into a surge suppressor to protect its circuit systems from damage during voltage spikes or surges. The surges may be caused by lightning and other power fluctuations. It is also recommended that the operator replace common parts. There are basic problems that the operator may solve such as replacing turntables, light bulbs and charcoal filters. To avoid overheating, water should not be heated in a microwave oven. In overheating, water may become hotter than the boiling water, a situation that may result in the sudden bursting of water if the cup or the glass is touched. This bursting could cause burns. Listed below are some of the safety precaution tips for microwave ovens. 1. Follow manufacturers’ instructions for operating procedures and safety precautions because misusing the oven could cause injuries 2. Always, check and confirm that the door seal and inside surfaces of door and oven cavity are thoroughly clean, especially after the device has been used 3. Repair or replace any microwave that malfunctions 4. Seek professional services for repairs 5. Do not use the microwave unless the door is closed. The door should not be bent, warped or damaged. 6. Do not disable or by-pass any safety locks. 7. Do not insert objects through an opening or around the door seal. Tips for Microwave Oven Maintenance The operator should always ensure that no damage occurs to the portions of the device that contact the door and door seals. As mentioned for safety reasons, a professional should do all the repairs. It is of the essence that the service personnel are aware of the risks associated with exposure to microwave energy when performing their tests and repairs works. Care should also be taken so that the right adjustment of applied voltages is done just as the replacement of the microwave power-generating component. Professionals should also undertake the dismantling of oven components and refitting of waveguides. The microwave power generator should also be done using the appropriate connection of load and output. Care must also be taken to prevent radiation from leaking out of the device. The question that many users or potential users ask is whether microwave ovens are safe. Microwave oven is often a safe and convenient method of heating and cooking if used and maintained according to manufacturers’ instructions (Michalsky, p. 54). It only requires the operator to take certain precautionary measures concerning the potential safety problems and health hazards associated with exposure to the high-energy electromagnetic radiation from the device. The other hazards the operator should look out for are relate to food handling, scalds and thermal burns. The safety issues raised about microwave oven is taken into account during its design. The design ensures that the waves are confined in the oven and are only generated when the device is switched on, with the door closed. The glass door is also designed in a manner that limits leakage of radiation. Only levels of leakage permitted by international standards are allowed through the glass door. Nonetheless, leakage may still take place, especially in modified and dirty ovens. Hence, microwave ovens should be well maintained continually to ensure they remain in good condition. Besides checking and ensuring the door closes properly, users should confirm that the safety interlock devices are properly fitted to the door to prevent microwaves from being generated while it is open, work correctly. Hence, the door seals must constantly be kept clean with no signs of damages to the seals or the outer casing. The other key area within which the safety of microwave oven should be considered is human health. The body can absorb the electromagnetic energy emitted from microwave ovens, thereby producing heat in exposed tissues. Some delicate organs such as the eye, which have low blood supplies and poor temperature control mechanisms or temperature-sensitive body tissues such as the testes, have a higher risk of heat-damage due to exposure to these high-energy radiations. Nonetheless, only long exposures to high-energy radiations are likely to result in thermal damage. Thermal injuries, which could result from handling of hot items, should also be preempted and prevented. In fact, microwave ovens cause quite peculiar thermal injuries, distinct from the burns obtained from other sources of heat. For instance, whereas in conventional stove, heated water releases steam via bubbling, microwave oven superheats water without any bubbles being formed on container wall. The sudden boiling of water in the microwave oven could result in burns that are more serious. Fault Tree Analysis Works Cited Ericson, C. A. Hazard Analysis Techniques for System Safety, 2005. John Wiley & Sons, Inc., Hoboken, New Jersey.  Evans, J. R., and William, M. L. The Management and Control of Quality, 2001. Mason, OH: South-Western Thomson Learning. Juran, J. M., and Frank, M. G. Quality Planning and Analysis, 1991. New York: McGraw-Hill. Michalsky, W. J. Top Tools for Manufacturers, 1998. Portland, OR: Productivity Press. Read More