There are two types of clean air systems that can be used for battery manufacturing
operations:
- Laminar Flow
(Supplied-Air)
Island Systems
- Clean Air Room
Both systems:
- Protect the worker from exposure to contaminated background air.
- Help propel dust produced at the workstation away from the operator's breathing zone.
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| Laminar Flow
(Supplied-Air) Island Systems |
Laminar flow (supplied-air) islands
(SAI) provide a zone of clean air at a workstation. The supplied air may come from
outside the plant or the air may be filtered plant air.
Laminar flow (supplied-air) islands are especially useful in limiting lead exposure when:
- An employee remains in a stationary position at the workstation for long periods of time. The
SAI provides an envelope of clean air to a worker. The clean air flows down over the worker
which normally keeps factory air from entering the clean air core.
- A supply of fresh, clean air is available. Note: Outside air may not require cleaning and
costs will be lower. If no outside source of clean air is available, intake air should be
filtered.
- The air is tempered. Employees will not remain in an environment that is too hot or too cold.
Note: If the air is not tempered employees will block off the air flow with cardboard or other
material in the winter or try to increase the flow for cooling in the summer which could
result in higher exposures.
Laminar Flow (Supplied Air) Islands
are not always
necessary if adequate
capture velocity is
provided to control
airborne lead.
Design
Specifications
The
laminar flow (supplied-air) island (SAI) should be designed to provide a laminar flow of
fresh air through the employee's breathing zone at a low enough velocity so that additional airborne
lead dust is not generated through reentrainment.
- The SAI height is typically 80 inches from the floor
but is often restricted by overhead clearance limits and other equipment installed in the area.
Curtains are used to extend the
length of the SAI to the operators breathing zone; cut pass throughs to prevent workers from
disturbing dust collected on the curtains.
- The
air flow is designed so that the velocity measured at the employee's breathing zone is 100-125 feet
per minute.
- SAIs can be used in conjunction with exhaust-ventilated work benches. In this case, the air should be
approximately balanced so that make-up air provided is nominally equal to the amount of the exhaust air.
It is recommended that the volume of make-up air be in the range of 90 to 110 percent of the exhaust
volume.
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| Clean Air Room |
Perform the following to ensure clean air rooms are free of lead contaminants:
- Vacuum enclosures and scrub
them with soap and water so lead dust does not collect on flat
surfaces.
- Ensure that the structural integrity of all enclosures
are intact and under positive pressure at all
times.
- Develop a preventive maintenance checklist that includes schedules for:
- Replacing ventilation system filters.
- Replacing ventilation system hoses, clamps, and blower internal parts.
- Replacing window and door moldings.
- Checking and replacing air shower ventilation systems, including automatic doors,
blower, nozzles, and
lighting.
- Monitoring intake and exhaust airflow to ensure that the rooms are under positive
pressure at all
times.
Design
Specifications
Using clean air rooms can effectively lower lead exposure.
They can be used for oxide mill or paste mix operators. Some clean air rooms are used as lead-free
environments where employees can remove their respirators.
- These rooms need to have positive pressure,
be tempered, and have a filtered air system with a HEPA filter designed to remove 99.97 percent of
lead dust greater than 0.3 micron in diameter.
- An ante room should be included to give employees a
place to remove their protective equipment without spreading contamination in the clean air rooms.
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