Filter Service Life.

Particulate Filter:

• Replace the primary filter when the flow rate is less than 18 CFM for one occupant or 22 CFM for two occupants.

• Flow rates are measured with a hot wire (CAF-recommended test procedure) and correlate to a differential pressure gauge to indicate minimum flow.

  When measuring with a hot wire instrument is not possible:

  1. Install a differential pressure gauge

  2. Install a new filter

  3. Run the system

  4. Mark the differential pressure gauge with a magic marker

  5. Replace filter when the reading of the pressure gauge is ½ of the original reading

Vapor Filter:

1. Directly monitor the vapors using real-time methodologies (recommended).

2. Measure the concentration of all vapors and calculate service life (may lead to incorrect filter life calculations).

3. When the first two approaches are not possible, replace the filter when one of the following three conditions occurs:

   1. Taste, odor, or symptom of a contaminant is detected within the enclosure.

   2. 12 months of use

   3. 500 hours of use