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How to Maintain Chemicals Below LEL Using a Ventilation System

Ventilation is required in order to control exposure to chemical hazards in the workplace. Initially, ventilation systems were used to control heating, airflow and air-conditioning; however, the Occupational Safety and Health Administration (OSHA) requires by law that ventilation systems be monitored and maintained for air contaminants. In addition, contaminants that are flammable are to be at a specific level known as the LEL (lower explosive limit). There is a multitude of steps that a facility can take in order to keep air contaminants at the LEL.

Instructions

- 1
  Maintain laboratory hoods. Continually monitor all laboratory hoods in the workplace to ensure that there are no complaints from workers. In addition, enforce proper training for hood instructions for all employees to ensure that each employee is capable of properly using the hood system.
- 2
  Train employees on the necessity of the ventilation system even if the ventilation system interferes with their productivity. The ventilation system can not be bypassed. If bypassed, the LEL levels will increase.
- 3
  Check all ducts for particles or buildup of materials. If your ducts are plugged or clogged, there is a possibility that they are poorly designed. In addition, make sure there is proper ventilation in the room, such as open access doors close to fans.
- 4
  Monitor all fans and centrifugal fans. Make sure the fans are working properly and that the blades are not worn out. If the centrifugal fans are working backward, they will deliver only up to 50 percent capacity.
- 5
  Investigate the emission sources. Record the relative contribution of each source. Record the chemical composition, temperature, rate of emission, pattern of emission, mass of emitted material and time intervals of emitted material. Reduce emissions as needed.
- 6
  Monitor the room temperature, air movement in regard to direction and velocity. Take measurements of the wind speed and directions and any type of effects due to the weather. Look at the air movement in relation to ventilation systems. Check the air changes per hour.
- 7
  Take any steps needed in order to reduce the LEL of chemical contaminants. Contact OSHA if you have any questions or need a ventilation evaluation or help in providing employees with working OSHA knowledge.

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