By Daniel N.D. AfuwaiE.M.D.C., A.B.U. ZARIA November 2011
Environment is defined as conditions influencing development or growth. Engineers, Technologist and Scientists are responsible for the environment that equipment are kept; where students and staff work , which should be conducive. Adequate care of equipment makes sense these days of dwindling funds in the Departments and personally. Due to lack of trained personnel we may find repairs very expensive.
If you misuse your equipment by not following the instruction in the manual provided by the manufacturer or do not protect it from environmental elements, you can be the cause of its failure. A few moments of care can yield many more hours of good performance. Proper preventive maintenance begins with an understanding of what we are fighting.
The following factors can influence the performance of your equipment: ◦ Extremes of temperature ◦ Moisture & corrosion ◦ Dust and foreign particles ◦ Power line problems ◦ Human factors Each of these can lead to equipment breakdown
The Ics, belts, insulators and other devices in the equipment are very sensitive to high temperatures. As long as boards and chassis are not too hot to touch, the amount of heat being produced should not cause any damage.
The following suggestions should help to prevent heat related failures: Keep the dust cover off during operations Allow plenty of ventilation around the unit Keep cooling vents clear and unblocked Keep system dust free inside and outside by using compressed air to rid the system of dust.
Towards the end of the dry season, rapid changes of temperature leads to build up of humidity and condensation on the metal chassis and circuit boards, which leads to tarnishing, short circuit and possibly damage to the equipment. Equipment should be covered with cotton cloth after use and not with plastic cover. Silical gel is useful in preventing build up of moisture in equipment
The metal connector pins on cables, circuit boards, IC pins, and other component leads are subject to corrosion. Corrosion can damage not only electronic connections in equipment but connections in mechanical section as well. Corrosion is caused by chemical attack from spilled reagents, corrosive atmospheres, and even touching delicate metal contacts with our fingers! Don’t touch circuit board contacts with your fingers because the oil in your fingers contain salt to begin oxidation of the pins.
The best preventive action is cleaning and lubrication to keep the electrical contacts, gears & bearings from oxidation buildup and prevent corrosion. Oxidation of some contacts can be cleaned by using soft rubber eraser, or contact cleaner spray. Do not use sand paper as it will grind the metal plating. Spraying the pins with contact cleaner spray is an effective corrosion preventive.
During the HARMATAN, dust is the main problem in Nigeria because dust enters through the smallest slots & cause problems such as: Dusty work place and living area Clogging of ventilation systems & moving parts Bad electrical Contacts Wear on all moving mechanical parts
The build up of dirt and dust on circuit boards creates an insulation blanket that prevents the release of heat generated during normal operation, which leads to overheating then failure of the mechanical or electronic components of the equipment. Dust settles on lenses and reflective surfaces leading to degradation in performance of optical systems.
Tobacco smoke increases the failure rate of rubber tires & belts in the mechanical section of equipment. Foreign particles such as food crumbs, are a great attraction for insects & rats!, which have been known to wreck havoc on rubber tubing and electrical cables. Therefore do not smoke instrument rooms or laboratories. Clean and clear up any food spills and crumbs.
If we clean our work area daily, if we cover our equipment after use with dust covers, the problem of dust is minimised and dust cannot accumulate. We have to do it ourselves, we cannot wait for someone else to do it for us. The use of oil free compressed air to blow out dust and dirt from inside the equipment at regular intervals is highly recommended. It is important to wash labs floors rather than sweep with brooms, because brooms raise dust into the equipment.
Good clean power supply is essential for the proper functioning of scientific equipment. Unfortunately, provision of this service is an exception rather than a rule. In fact over 50% of equipment breakdown can be traced to problems caused by power fluctuations and erratic supply. There are four types of power line problems that cause concern: Brown outs & line dips Blackouts Mains borne Transients Noise
Brownouts – are those planned and sometimes unplanned reduction of voltage resulting from an unusually high demand in electric power. This 5% to 15% drop in voltage can last for several hours. During brownouts, equipment tend to operate intermittently, motors/fans tends to overheat & some equipment simply shut down while others lock up. Do not operate equipment during a brownout as it places a severe stress on the equipment and accelerates the condition of which equipment power supply fails.
A voltage dip –is a short reduction in line voltage due to a mains fault or sudden increase in electrical load. This happens when equipment are operated in the same line with arc welders, grinding machines or air conditioners. This is very harmful to sensitive equipment as computers. A blackout is a total loss of line voltage. When power goes out be careful and be sure that when power is restored – a tremendous voltage spike will be produced as lights & motors go On all over the neibourhood, which could damage your equipment.
Always unplug your equipment when a blackout occurs, and wait till power is restored for some few minutes before plugging in the instruments. The automatic voltage switch (AVS) and Uninterruptable Power Supply (UPS) are indispensable. Line Transients are a momentary overvoltage/ under voltage conditions often cause by lightning, start up of nearby large electrical equipment such as motors or arc welders. Transients disrupts system operation of microprocessors or damage sensitive equipment.
Electrical Noise consists of high frequency and high voltage interference on the power line and often affects equipment such as pH metres, computers, radios, tvs etc. Its main symptoms are visible white streaks in the lower portion of the computer screen, and in pH metres unstable readings. These problems are solved using filters, grounding the installation and shielding the signal leads of the instrument properly.
1. Use uninterruptible power supply(UPS) of adequate power rating for the equipment in question. 2. Use of ferro-resonant transformer type Line Conditioner. 3. Use of voltage stabilisers that use electronic components and relays; these are useful in the absence of line conditioners as they are affordable.
ELECTRICAL PRECAUTION ◦ a, All single phase mains sockets and plugs should be three pin. ◦ b, Connections between equipment and plugs should be made with three core flexable cable of suitable current rating. ◦ C, Use the correct fuse for the equipment chosen as provided or calculate the current drawn by the equipment and use it to select the fuse. The formula is Current(I) = Power(P) divide by Voltage (V). (Give example on board). NEVER use a nail or a very thick length of wire to replace a fuse , even as a temporary measure. ◦ D. Plugs and other fittings should be wired correctly. This to be done practically
Sockets should not be overloaded. If using a number of plugs (equipment) the proper multi- way adaptors should be used and the total rating of the equipment attached should not exceed the maximum rating of the socket. Equipment should be isolated from the mains whilst maintenance takes place. All plugs, sockets and wiring should be inspected and tested by competent person at least twice a year, for earthing, insulation, isolation and suitable fuses.
TO CONCLUDE Ensure that no one, as a result of using electrical equipment, is ever put in a situation where an electric current might pass through his body. Ensure that unnecessary electrical heating never occurs in wires, cables, flexes, plugs, sockets or connectors. THANKS