Law Department notice on WTC document preservation, Oct 2001

NYC 9/11 Public Portal Document

10. Encapsulation: The application of a bridging (resurfacing) or penetrating compound on internal ventilation system surfaces to bond, mechanically resurface, or lock-down fibrous and other ventilation system components which have deteriorated or been damaged, to control the entrainment of particulates from these components into the airstream.

11. Environmental Cleaning Contractor: The Environmental Cleaning Contractor at 110 Liberty Street is WRS Infrastructure and Environment, Inc., as the authorized by the USEPA.

12. Environmental Service Contractor: An independent environmental contractor performing an initial assessment of the WTC-related dust, as authorized by the USEPA

13. Fan: A power driven machine that moves a volume of air by converting rotational mechanical energy to an increase in the total pressure of the moving air (See AMCA 99-86).

14. HEPA Filter: High efficiency particulate air filter capable of a 99.97% collection efficiency for a 0.3 micron size particle as per DOP testing.

15. Mechanical Cleaning: Physical removal of debris and other foreign matter from ventilation system surfaces.

16. Negative Air (Vacuum Collection) Cleaning: Procedure for removal of debris from a ventilation system using a HEPA-filtered Vacuum Collection Device for particulate control and capture.

17. Non-Porous Surface: Any surface of the ventilation system in contact with the air stream which cannot be penetrated by either solutions or air. This would exclude ventilation system materials such as wood, fiberboard, thermal/acoustic insulation, and concrete.

18. Porous Surface: Any surface of the ventilation system in contact with the air stream which can be penetrated by either solutions or air, including but not limited to ventilation system materials such as wood, fiberboard (ductboard), fibrous thermal/acoustic insulation, and concrete.

19. Pressure Drop: (1) Loss in pressure, as from one end of a refrigerant line to the other, from friction, static, heat, etc. (2) Difference in pressure between two points in a flow system, usually caused by fnctional resistance to fluid flow in a conduit, filter, or other flow system (See ASHRAE Terminology of Heating, Ventilation, Air Conditioning, and Refiigeration, 1991).

20. Sanitization: A process to reduce the proliferation of microbial growth in an ventilation system, usually involving the application of a biocide agent.

21. Source Removal: An HVAC hygiene mitigation process, which involves the physical capture, removal, and controlled containment of foreign matter from an ventilation system.

22. Static Pressure: The normal force per unit area that is exerted on the interior surfaces of the ventilation system by the air.

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