In keeping with the Physics Division policy to give the
highest priority to Environmental, Safety, and Health concerns in its
operations, it is the intent of Physics Division management to minimize
cryogenic hazards to staff and visitors and to assure adherence to applicable
safety codes. This will be accomplished through the development of
operational procedures, the proper training of personnel, the design of
equipment, and the establishment of a Cryogenic Safety Committee.
Responsibilities and Functions
The Physics Division Cryogenic Safety Committee shall
consist of at least three Physics Division members appointed by the Division
Director and a member from the ESH Division.
Members having expertise in cryogenics from other divisions
may be appointed at the discretion of the Division Director.
The Divisional Safety Coordinator shall be a member of the
Ad hoc members will be invited to participate in safety
reviews of specific cryogenic equipment or when membership expertise needs to
Frequency of Meetings
This Committee will convene at least quarterly in order to
fulfill its responsibilities and accomplish the mandates as specified in this
Amendment of the Charter
The Committee will review the terms of its charter on an annual
basis and at other times as needed and make recommendations for change to the
Director of the Physics Division.
The Physics Division Cryogenic Safety Committee will report
to the Physics Division Director.
The Committee’s membership must be approved by the
Physics Division Director.
1.2 Definition and Scope:
temperatures are defined as those below 120 K (-153◦C).
The safety criteria established in this document apply to the cryogens in use
in the Physics Division, namely liquid helium and nitrogen. Flammable
fluids, such as hydrogen, and reactive liquids, such as oxygen and fluorine,
are excluded. The use of flammable cryogens will require special approval
procedures not outlined in this document.
of Cryogenic Safety Hazards
safety hazards associated with the use of cryogenic liquids (Appendix 1) can be
categorized as follows:
or low-temperature gas from any of the specified cryogenic substances will
produce effects on the skin similar to a burn.
of asphyxia will occur when the oxygen content of the working environment is
less than 20.9% by volume. Effects from oxygen deficiency become
noticeable at levels below ~18% and sudden death may occur at ~6% oxygen
content by volume. This decrease in oxygen content can be caused by a
failure/leak of the cryogenic vessel or transfer line and subsequent
vaporization of the cryogen.
flux into the cryogen from the environment will vaporize the liquid and
potentially cause pressure buildup in cryogenic containment vessels and
transfer lines. Adequate pressure relief must be provided to all parts of
a system to permit this routine outgassing and prevent explosion.
fluids with a boiling point below that of liquid oxygen are able to condense
oxygen from the atmosphere. Repeated replenishment of the system can
thereby cause oxygen to accumulate as an unwanted contaminant. Similar
oxygen enrichment may occur where condensed air accumulates on the exterior of
cryogenic piping. Violent reactions, e.g. rapid combustion or explosion,
may occur if the materials which make contact with the oxygen are combustible.
and Administrative Responsibility
is the responsibility of the experimenter in charge of an apparatus to ensure
that the cryogenic safety hazards are reduced to as low a level as is reasonably
achievable. This will entail (1) a safety analysis and review for all
cryogenic facilities, as described in Section 3, (2) cryogenic safety and
operational training for relevant personnel, (3) upkeep of appropriate
maintenance and inspection schedules and records.
is emphasized that it is the responsibility of the experimenter to maintain the
system in the original working order, i.e. the condition in which the system
was approved for use. Alterations to the system which impact worker safety
must be reported to the Physics Division Safety Coordinator.
ultimate responsibility for safety rests with the worker and is best ensured by
thorough education and awareness