UFC 4-211-02N
10 January 2005
including change 3, 13 April 2007
\ APPENDIX B: OSHA INTERPRETATIONS AND REFERENCES FOR
REDUCED AIRFLOW AND RECIRCULATING AIRFLOW
This appendix is included as an aid to the designer for information regarding
OSHA requirements for both reduced airflow velocity in the painting zone and
allowance of recirculation of exhaust air when proper measures are taken for
corrosion control hangars. The U.S. Air Force, which bears the largest share of
corrosion control expenses for its fleets of aircraft, have taken a pro-active
approach in these matters. Refer to Appendix B, page, B-4, of AFRL-ML-TY-TP-
2004-4518, for a detailed analysis, response and requirements of the OSHA
interpretations and supporting calculations for the recirculating model. The
following is the Abstract from that publication-
"The text of 29 CFR 1910.107(d)(9), which was imported from the 1969 revision
of a fire safety standard, prohibits recirculating ventilation in spray painting
facilities. Devices to measure vapor concentrations obsolete this standard almost
immediately, but efforts to amend this statement have been frustrated. To
accommodate advances in technology, OSHA invoked the designation "de
minimis violation" to enable the use of recirculation and other technologies that
comply with the most current consensus standards applicable to their operations
. . . when the employer's action provides equal or greater employee protection.
Whereas industry has adapted to this expedient, Department of Defense
agencies have consistently interpreted that if 107(d)(9) is still in print and the
alternative is called a violation, however qualified, military installations will not be
given permission to employ exhaust recirculation (ER). Individual bases working
in isolation have built a few examples of painting hangars using ER, but each of
these facilities suffered from one or more serious design faults. Robins Air Force
Base (RAFB), near Macon, Georgia, is acquiring a painting hangar to
accommodate painting of C-5 aircraft in an ER ventilation system. Because the
economics of exhausting 2.5 million cfm of temperature-controlled air is
untenable, critical justification for using ER is provided by RAFB's environmental
conditions, which require cooling and dehumidifying air used in the ventilation
process during four to five months each year. This report identifies documentary
precedents for competent designs of future paint facilities and describes the
preparation and issuance of a design-and-build contract for construction of this
new facility at RAFB."
..........Consistent with the interpretations12, 14, and 16 above, OSHA inspectors
did not cite L3 or Air Force facilities using ER ventilation to paint aircraft at
Seymour Johnson Air Force Base (SJAFB), N.C., and at Mountain Home AFB
(MHAFB), Idaho. SJAFB's facility design placed a vapor control system inside
the ER loop, lowering17 both total emissions and the increase in exposure within
the workplace. The concept earned a 1994 award by EPA for environmental
excellence and has profound implications17 for source reduction strategies."
A-5
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