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Every local exhaust ventilation (LEV) system will undergo inspection, testing and examination at regular interval. This is important to ensure the system works properly and efficiently. To meet the design specification, each new system installed are advise to go through quality test and examined. This is to make sure the airflow through each of the hood is sufficient to extract contaminant effectively away from the workroom.

Best time for Local Exhaust Ventilation Inspection

Basically, once in a month is the best time to do inspection on local exhaust entilation (LEV) system. The purpose of inspection is to ensure the system functioning properly and effectively.

Local Exhaust Ventilation (LEV) | Zabsi

Local exhaust ventilation (LEV) system inspection consists of it’s all component physical condition, observation of how the work carried out in relation to the utilisation of LEV system, smoke tube tracer test, identifying if there is any thing that can be obstruction of flow, observation of condition surrounding and near the hood, inspection on the air cleaner device and maintenance of the fan’s motor. If there is indication reduction in flow, can carry out the testing and examination every 12 months.

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During the inspection, precautionary measures on inside of ducts important to prevent chemical poisoning or exposure to chemical hazards; on motors to prevent contacts with dangerous part of motor that can hurt injured a person; on passages and scaffolds to prevent slip or fall down and on electric parts to prevent electric shock.

Instruments used during inspection.

  1. smoke tube to indicate direction of air flow.
  2. manometer for measuring static pressure.
  3. traverse pitot tube connected to a manometer for measuring velocity pressure.
  4. surface/glass thermometer for measuring bearing box surface temperature.
  5. a test hammer for sound test of thick wall ducting.
  6. a wooden or bamboo bar used for sound test of thin wall ducting.
  7. a tachometer for measuring fan speed,
  8. an anemometer for measuring air velocity.

Inspection item

Hood, duct, damper, fan and air cleaner are such inspection items. Hood inspection includes physical appearance, obstruction of flow, direction and size of opening area for exterior hoods, velocity, environmental monitoring and static pressure. Whereas for the duct are its outer and inner surface physical condition, loose joints, condition of inspection holes, static pressure, velocity and temperature in the duct. The inspection of damper and air cleaner are its condition and static pressure. Fan inspection consists of its condition of outer and inner casing surface, impellers and guide vanes, belts, bearings and rotating direction of the fan.

Subsequently, inspection of Local Exhaust Ventilation (LEV) system is utmost necessary to carry out to determine its effectiveness and efficiency.

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