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How to Conduct HEPA Filter Integrity Test procedure? DOP Test

The HEPA filter integrity test is typically performed on cleanroom supply air HEPA filters using a photometer to scan the filter surface for pinhole leaks that could allow the transmission of contaminant particles that would be unacceptable in a critical application.

Which test is used for the validation of HEPA filter?
Dispersed Oil Particulate (DOP) testing, also known as filter integrity testing, is the process in which the integrity of your HEPA (High Efficiency Particulate Air) or ULPA (Ultra Low Penetration Air) filter is challenged through introducing particulates and measuring the output.

  1. Keep the instrument in the area.
  2. Ensure that the instrument used for DOP testing is calibrated and calibration is valid.
  3. Provide Nitrogen / Compressed air to the DOP smoke generator.
  4. Keep the smoke generator in the supply air plenum.
  5. Smoke will travel through supply air and come out through HEPA Filter.
  6. Check the 100% concentration before filter.
  7. Move the sensing probe at not more than 10 feet per minute at a maximum of 1 inch under the HEPA Filter complete area.
  8. If leakage is there, needle on dial will show the deflection, Tighten the filter properly and again repeat above procedure.
  9. If the penetration of smoke is less than acceptable limit the filter passes DOP test.
  10. If probe shows penetration more than the acceptable limit within area of filter, then filter is leaking. So replace filter and repeat the above procedure.
  11. Collect the test certificates from the outside agency and check as per requirement.
  12. Take five reading with vane type Anemometer in a plane parallel to and 6 inch downstream of the HEPA filter in feet per minute. (four corners and one center).
  13. Note down the reading and calculate the average velocity.
  14. If the velocity is less than the acceptable limit, check and reset the damper. Even after correction if the velocity is below the acceptable limit, the filter is choked and replace the same.
  15. Carry out the above test on the new filter.
  16. Carry out the above qualification once in a year.

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  1. Sir, this practice has been upgraded with the Poly Alfa Olefin & scanning rate of the filter to per second with complete upstream concentration micro gram per ml.