GROUND FORCE 717H01 - Page 12

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2.11 CONFINED SPACE SAFETY
Some maintenance procedures on Ground Force
Worldwide water trucks require entering the tank
itself. Working inside a conned space such as a
water tank is highly dangerous. Technicians work-
ing inside the tank must follow safety guidelines.
To work safely in a conned space, the entrant
must be able to communicate with the attendant
who is on duty outside the space. A system of com-
munication must be set up prior to beginning work.
The attendant must always be aware of what is
going on inside the space in order to be able to
react in event of an emergency.
Oxygen-decient atmospheres have less than 19.5
percent available oxygen by volume while normal
air contains approximately 21 percent oxygen.
Deviations from normal concentrations are a major
concern in conned spaces.
Ground Force water truck tanks are considered
“Permit-Required Conned spaces," based on the
following guidelines:
• Contains or has a potential to contain a hazardous
atmosphere.
• Contains a material that has the potential for engulf-
ing an entrant.
• Has an internal conguration such that an entrant
could be trapped or asphyxiated by inwardly converg-
ing walls or by a oor which slopes downward and
tapers to a smaller cross-section.
• Contains any other recognized serious safety or health
hazard, ex., reduced visibility, darkness, etc.
Equipment will include at a minimum:
• Ventilation Fans (1 minimum for Assembly, 2 minimum
for Fabrication) and hoses.
• A calibrated and tested air monitor.
• PPE appropriate to the tasks or jobs being performed.
• Lighting equipment appropriate to the task or jobs
being performed.
• Signs posting the conned space and restricting
access.
• Stanchions or other barriers restricting the access of
non-permit personnel.
• Radio equipment as necessary to support communica-
tion between the attendant(s) and entrant(s)
• Rescue equipment tested and in a place near the
conned space and readily available for rescue
personnel.
• OSHA requires that a standby person be present with
suitable rescue equipment when self-contained
breathing apparatus or hose masks with blowers are
used in atmospheres immediately dangerous to life or
health.
The following are other hazards you should consider when
evaluating a conned space:
• Temperature extremes can have an adverse effect on
entrants. For example, if a space has been steam-
cleaned, it must cool before any entry is made.
• Engulfment hazards such as loose material (grain,
sand, coal, etc.) can crust over in a bin and break
loose under your weight and trap you during entry.
• Noise can become excessive in a conned space and
can not only damage hearing but can affect communi-
cation, causing warnings to go unheeded.
• Slick/wet surfaces can cause slips and falls and
increase the chances of electric shock.
• Falling objects are a danger if work is being done
above the entrant in a conned space.
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SAFETY