1. Authorisation
§ Authorisation from academic-in-charge, is required to undertake work in the metallography laboratory
§ Potential user should complete the risk control worksheet and assessment
§ Potential user should be trained by a qualified or licensed user
2. Hazards associated with equipment/process:
§ Electrical hazards associated with the use 240 VAC electrical appliances.
§ Ultrasonic energy can cause damage to joint tissues if fingers or any other part of a body is immersed in the cleaning fluid of an operating ultrasonic cleaner.
§ Prolonged exposure to high frequency sound emitted from an operating ultrasonic cleaner unit may lead to hearing impairment.
§ Organic solvent is flammable, harmful and may be reactive hazard if mix with other chemicals.
3. Preparation for work:
§ Locate first-aid box, safety shower, eye wash, emergency telephone, emergency exits and fire extinguisher.
§ Locate MSDS and risk assessment in the folder behind the lab door.
4. Personal protective equipment (PPE) to be used:
§ Safety glasses, closed-toe shoes, protective gloves, lab coat, mist mask.
§ Loose and long hair should be tied back away from the face.
5. The environment where the task is to be undertaken:
§ The ultrasonic cleaner unit should be mounted on a level surface, free from extreme temperatures, strong vibrations and corrosive environment to protect the equipment from damage.
§ Working bench and floor should be dry and clean to avoid electric shock, slip and contamination.
§ No naked flame, heat or ignition source in the vicinity
§ No eating, drinking or smoking
6. Step-by-step working procedures
a) Wear PPE as mentioned above.
b) Visually inspect condition of the ultrasonic cleaner unit and the electrical connection is satisfactory.
c) If necessary, clean and fill the tank with water to the appropriate level. Do not over fill with water that causes water to spill over the top of the tank. Too low a water level will result in poor cleaning efficiency and may cause transducers damage.
d) Ensure that the external surface and electrical connection are thoroughly dry before plugging the cleaner to the mains supply.
e) Suspend the stainless steel mesh tray inside the water-filled tank. Items to be cleaned should not be placed directly on the tank bottom; otherwise the transducers could be damaged because of ultrasonic energy reflecting directly back to the transducers
f) Fill a small beaker with the cleaning solution to the level sufficient to cover the item to be cleaned.
g) Gently lower the beaker onto the mesh tray suspended inside the water-filled tank. Care should be taken not to allow water to overflow the top of the tank. The beaker should be stable when seated on the mesh tray. Otherwise add more cleaning solution for more weight.
h) Switch on the unit to degas both the water and the cleaning solution. Cover the lid to reduce noise and aerosols escaping. Degassing will provide optimal cleaning.
i) After 5-10 mins of degassing, switch off the unit and gently put the item to be cleaned (using a pair of forceps or tongs) in the beaker of cleaning solution. Switch on the unit and cover the lid.
j) Monitor the cleaning process regularly; if necessary, use the timer switch. Switch off the unit to inspect the item.
7. Clean-up procedures
§ If the water in tank is contaminated, unplug the unit from the mains before draining the contaminated water.
§ Thoroughly rinse the tank with fresh water. If necessary, clean inside of tank with sponge and mild detergent.
§ Fill the tank with clean water.
§ Dry all external surfaces of the unit with particular attention on the electrical connection and socket.
8. Waste disposal procedures
§ Dispose of any waste organic solvent in the designated receptacle for eventual disposal through Chemsal.
§ Dispose of other cleaning solutions as per respective MSDS guidelines.
9. Emergency procedures
§ In case of emergency alarm or power outage, leave the lab in an orderly manner.
§ Use the emergency red phone or dial ‘333’ for any emergency.
§ For minor injury requiring first aid treatment, use the first-aid cabinet or contact the nearest first-aider.
§ In case of minor spills, wear appropriate PPE and wipe spills with paper towels.
§ Report any major spills; a general chemical spill treatment kit (in Room 179) may be used. Refer to MSDS for further procedures.
§ If contact with acetone or ethanol, rinse skin or eyes with fresh running water.
10. After-hours access procedures
§ After-hours access is restricted; contact person-in-charged for after-hours authorization.
§ Register your details in the after-hours log book if the metallography lab is to be used after normal working hours.
§ Only trained and licensed user of the equipment is allowed to enter the log book.
11. Associated Documents
§ Risk assessment for ultrasonic cleaning
§ MSDS for ethanol
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