28-11-00
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757
MAINTENANCE MANUAL
~............................................................................. | HEALTH-SAFE CONDITION | | | | A HEALTH-SAFE CONDITION OCCURS WHEN THE OXYGEN CONTENT IS A | | MINIMUM OF 19.5% TO A MAXIMUM OF 23.5% BY VOLUME AT SEA LEVEL, | | AND THE VAPOR CONCENTRATIONS ARE BELOW THESE PERMISSIBLE EXPOSURE | | LIMITS: | | | ............................................................................... | | Permissible Exposure Level | | | | Total Hydrocarbons TWA *[1]| Lower Explosive Level | | Fuel | (ppm) | (percent) | ............................................................................... |Aviation Gasoline | 300 | 1.0 | ...............................................................................
|Jet A | | |
|Jet A-1 | 160 | 0.7 |
|JP-5 | | |
|JP-8 | | |
2..................…..............................…...........................1
*[1] TWA - Time Weighted Average
S 912-217
(8)
Lower Explosive Limits (LEL):
(a)
The minimum concentration of flammable vapors in air below which propagation of flame does not occur on contact with a source of ignition.
S 912-218
(9)
Permissible Exposure Level (PEL):
(a)
The time weighted average airborne concentrations of substances at which it is believed that nearly all workers may be repeatedly exposed 8 hours a day, 40 hours a week, without adverse health effects.
NOTE: The PEL limits used in this procedure are the PEL limits
____ used by Boeing personnel during fuel tank entry. If the local PEL limits are more restrictive than the ones given in this procedure, use the equivalent local PEL limits.
S 912-219
(10)
Purging or Purged (For Fuel Tank Entry):
(a)
Purging an aircraft fuel tank is defined as the removal of any fuel or fuel vapor that remains after the fuel tanks are sumped. A purged fuel tank contains a nonflammable atmosphere that can be maintained by mechanical ventilation.
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28-11-00
ALL ú ú 01 Page 206 ú May 28/99
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757 MAINTENANCE MANUAL
S 912-220
(11)
Unwanted Sources of Ignition:
(a)
Unwanted sources of ignition include 1) Open flames (matches, cigarette lighters etc.) 2) Electrical equipment (lights, motors, sparks from engine
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