CHART TRIFECTA 2K, Руководство по обслуживанию

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4 Trifecta 2K
Prior to reusing a damaged container, the unit must be tested, evaluated, and repaired as
necessary. It is highly recommended that any damaged container be returned to MVE for repair
and re-certification.
The remainder of this safety bulletin addresses those adverse environments that may be
encountered when a cryogenic container has been severely damaged. These are oxygen
deficient atmospheres, oxygen-enriched atmospheres, and exposure to inert gases.
OXYGEN DEFICIENT ATMOSPHERES
The normal oxygen content of air is approximately 21%. Depletion of oxygen content in air,
either by combustion or by displacement with inert gas, is a potential hazard and users should
exercise suitable precautions.
One aspect of this possible hazard is the response of humans when exposed to an
atmosphere containing only 8 to 12% oxygen. In this environment, unconsciousness can be
immediate with virtually no warning.
When the oxygen content of air is reduced to about 15 or 16%, the flame of ordinary
combustible materials, including those commonly used as fuel for heat or light, may be
extinguished. Somewhat below this concentration, an individual breathing the air is mentally
incapable of diagnosing the situation. The onset of symptoms such as sleepiness, fatigue,
lassitude, loss of coordination, errors in judgment and confusion can be masked by a state of
“euphoria,” leaving the victim with a false sense of security and well being.
Human exposure to atmosphere containing 12% or less oxygen leads to rapid
unconsciousness. Unconsciousness can occur so rapidly that the user is rendered essentially
helpless. This can occur if the condition is reached by immediate change of environment, or
through the gradual depletion of oxygen.
Most individuals working in or around oxygen deficient atmospheres rely on the “buddy
system” for protection - obviously, the “buddy” is equally susceptible to asphyxiation if he or
she enters the area to assist an unconscious partner unless equipped with a portable air supply.
Best protection is obtainable by equipping all individuals with a portable supply of respirable
air. Lifelines are acceptable only if the area is essentially free of obstructions and individuals
can assist one another without constraint.
If oxygen deficient atmosphere is suspected or known to exist:
1. Use the “buddy system”, and use more than one “buddy” if necessary to move a fellow
worker in an emergency.
2. Both the worker and “buddy” should be equipped with self-contained or air line
breathing equipment.
OXYGEN ENRICHED ATMOSPHERES
An oxygen-enriched atmosphere occurs whenever the normal oxygen content of air is
allowed to rise above 23%. While oxygen is non-flammable, ignition of combustible materials
can occur more readily in an oxygen-rich atmosphere than in air; and combustion proceeds at a
faster rate although no more total heat is released.