scope:

This standard discusses portable ventilation equipment and systems used for the reduction, control, or prevention of exposure to hazardous atmospheres or airborne substances in the occupational environment, and for provision of comfort to employees.

Note: Portable ventilation systems are an important engineering control for establishing and maintaining acceptable air quality and supplementing the effectiveness of fixed systems in the work environment. The major approaches employed in the use and application of portable ventilation systems include provision of clean tempered air to provide and maintain comfort, displacement of airborne contaminants from the workspace, dilution of airborne contaminants in the workspace, supplying breathable air to eliminate or prevent oxygen deficiency in an environment (positive pressure ventilation), and the capture or containment of airborne contaminants at or as close as possible to the point of generation (negative pressure ventilation). Properly designed, installed, and operated portable ventilation systems can provide excellent control of airborne contaminants.

This standard establishes minimum requirements for the design, construction, and labeling of portable ventilation equipment and systems.

This standard also establishes fundamental requirements for the application, management, operation, maintenance, performance validation, and testing of portable ventilation equipment and systems to ensure satisfactory performance over their lifetime.

This standard covers components of portable ventilation systems, including:

• air movers and their modes of power

• other components of portable ventilation systems including entry hoods; duct, hose, and other conveying structures; air-cleaning equipment including filters and sorbent air-purifying devices; and air coolers and heaters

This standard does not intend to address every application and technical problem that arises during the use of portable ventilation systems in industry. The manner in which portable ventilating equipment is used requires judgement and discretion by the end user.

Note: There is no simple formula governing decisions concerning use of this equipment. The end user should refer to appropriate technical references and publications, such as included here, for further guidance on uses and applications and strengths and limitations of portable ventilation systems in specific applications.

Containment materials may be temporary in nature and made from tarps or plastic sheeting. These materials may not hold up to the static pressures needed for capture of particulates nor for removal of other contaminants. Thus, the balance of various factors involved in use of temporary containments may not eliminate all hazards within environments. Additional measures are often required for such situations, e.g., abrasive blasting and industrial painting.

The standard does not cover:

• air recirculation systems, such as recirculating fume hoods, intended for use in laboratory applications

• air moving systems that are part of fixed or continuous industrial processes

Note: Vacuum cleaners, including industrial vacuums, and HEPA filtered vacuums are sold as an integrated unit. Several OSHA standards, such as the new silica standard, require use of HEPA vacuums. These units are self-contained except for attaching the flexible collection hose and, occasionally an exhaust hose. When using equipment, refer to the manufacturer's instructions regarding these units.

Where provisions of this standard conflict with other standards, the more stringent shall apply.

Note: Requirements stated in other non-regulatory standards including other standards in the Z9 series may not apply to portable ventilation systems for technical reasons. ANSI/ASSP Z9.4, for example, is limited in scope to fixed locations rather than temporary locations such as construction sites. Air flow from portable equipment can interfere with use of process equipment such this form of ventilation can overpower the spray characteristics of a paint spray gun to render it unusable. The use of dilution ventilation requires unusual design considerations. ANSI/ASSP Z9.10 which covers dilution ventilation is intended for use in in fixed locations. ANSI/ASSP Z9.10 uses efficiency K values (now referred to as Mi values) of 1 to 2. Temporary containments often require higher values for efficiency. The Industrial Ventilation Manual published by ACGIH discusses the selection of appropriate efficiency values.