Clarke 56381408 (21KBCATCLDC), Руководство оператора, Страница: 4 / 64

A-4 / ENGLISH
A-4 - FORM NO. 56091023 - PBU Propane Burnisher with Dust Control
ENGINE EMISSIONS AND CO SAFETY
Potential Effects of CO Exposure
· Work place/industry guidelines for CO exposure limits
· De fi nition of CO effects
Work place/industry guidelines for CO exposure limits
Limits for permissible exposure to CO vary substantially from region to region. City, State, and Industry requirements should be consulted prior to
use of any equipment.
The current Occupational Safety and Health Administration (OSHA) Permissible Exposure Limit (PEL) for CO is 50 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 Total 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
Total time interval and PPM 8 HR Total ppm = 400k
The current National Institute for Occupational Health and Safety (NIOSH), immediately dangerous to life and health concentration (IDLH)
recommended level for CO is 1,200 ppm. NIOSH de
fi nes the IDLH exposure level as the concentration that could result in irreversible health
effects or death, or prevent escape from the contaminated environment within 30 minutes.
De fi nition of CO effects
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 hemoglobin molecule, carboxyhemoglobin is incapable of
carrying Oxygen. The af
fi nity of hemoglobin for CO is 200 to 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) in
inspired air, since this will not raise blood saturation above 10 %. 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.
AIR QUALITY MONITORING
WARNING!
Deployment of a monitor/detector is essential for the safe operation of any equipment that has the potential to produce CO. CO sensors/detectors became available on the mass
market around 1978. At present several brands sell in the
fi fty-dollar range. The main differences between the technologies involved are battery or electric and Semiconductor or
Biomimetic types. Detectors for carbon monoxide (CO) are manufactured and marketed for use in either the home or occupational industrial settings. The detectors for home use
are devices that will sound an alarm before CO concentrations in the home become hazardous. There is an Underwriters Laboratories, Inc., performance standard (UL 2034) for
residential CO detectors. Detectors currently available on the market are battery-powered, wall mount, Operator worn portable personal protective, plug-in, or hard-wired. Some
models incorporate a visual display of the parts per million (ppm) concentration of CO present in the home. For more information on CO detectors for home use, call the Consumer
Product Safety Commission Hotline at 1-800-638-2772. CO detectors for use in residential settings are not designed for use in typical workplace settings. Monitoring requirements in
an occupational setting are different from monitoring requirements in the home. In the workplace, it is frequently necessary to monitor a worker’s exposure to carbon monoxide over an
entire work shift and determine the time-weighted average (TWA) concentration of the exposure. It may also be necessary to have carbon monoxide monitors with alarm capabilities
in the workplace. The direct-reading instruments are frequently equipped with audio and/or visual alarms and may be used for area and/or personal exposure monitoring. Some have
microprocessors and memory for storing CO concentration readings taken during the day. It is signi
fi cant to note that some of the devices mentioned for workplace CO monitoring are
not capable of monitoring TWAs, and not all are equipped with alarms. The appropriate personal protective monitor must be chosen on an application-by-application basis. For more
information on the availability of workplace CO monitors or their application, call the National Institute for Occupational Safety and Health at 1-800-35-NIOSH (1-800-356-4674).
revised 3/11