PBU Operator's Manual (EN) - Propane Stripper FORM NO. 71506A - 5 -
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ENGLISH
Engine Emissions and CO Safety
PotentialEffectsofCOExposure
· Workplace/industry guidelinesfor CO exposure limits
· DefinitionofCOeffects
Workplace/industryguidelinesforCOexposurelimits
Limits for permissible exposure to CO vary substantially from region to region. City, State, and Industry require-
ments should be consulted prior to use of any equipment.
ThecurrentOccupationalSafetyandHealthAdministration(OSHA)PermissibleExposureLimit(PEL)forCOis50
ppm, as an 8-hour time weighted average (TWA). This is computed by making measurements at intervals over 8 hours,
then adding the sums of the concentrations and the intervals, and dividing by 8 hours. For example:
Time Interval PPM
8:00-9:00 1 HR 100
9:00-10:00 1 HR 25
10:00-11:00 1 HR 25
11:00-12:00 1 HR 50
12:00-1:00 1 HR 50 400ppm/8HR=50ppm TWA
1:00-2:00 1 HR 50
2:00-3:00 1 HR 50
3:00-4:00 1 HR 50
Time intervals = 8 HR ppm = 400
The current National Institute for Occupational Health and Safety (NIOSH), immediately dangerous to life and
healthconcentration(IDLH)recommended level for CO is 1,200 ppm.NIOSHdefinestheIDLHexposurelevelasthe
concentration that could result in irreversible health effects or death, or prevent escape from the contaminated environ-
mentwithin30minutes.
DefinitionofCOeffects
The toxic effects of carbon monoxide in the blood are the result of tissue hypoxia (lack of oxygen). carbon monoxide
combines with hemoglobin to form carboxyhemoglobin. Since CO and oxygen react with the same group in the hemoglo-
binmolecule,carboxyhemoglobin is incapable ofcarryingOxygen. The affinity ofhemoglobinfor CO is200to 240 times
greater than for oxygen. The extent of saturation of hemoglobin with CO depends on the concentration of the gas, the
quantity of inspired air and on the time of exposure. The severity depends on the state of activity of the individual and
his tissue oxygen needs.
According to Harrison’s Principles of Internal Medicine 7th edition, no symptoms will develop at a concentration of
0.01%CO(100ppm)ininspiredair,since this will not raisebloodsaturationabove10%.Exposure to 0.05% (500ppm) for
1 hour during light activity will produce a blood concentration of 20% carboxyhemoglobin and result in a mild or
throbbing headache. Greater activity or longer exposure causes a blood saturation of 30 to 50 %. At this point head
ache, irritability, confusion, dizziness, visual disturbance, nausea, vomiting, and fainting can be experienced. Exposure
for one hour to concentrations of 0.1% (1000ppm) in inspired air the blood will contain 50 to 80% carboxyhemoglobin
which results in coma, convulsions, respiratory failure and death. On inhalation of high concentrations of CO, saturation
of the blood proceeds so rapidly that unconsciousness may occur suddenly without warning.
