Working safely with cryogenic liquids

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Working safely with cryogenic liquids   Reyer
Jochemsen
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Cryogenic liquids
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Working safely
avoid contact avoid pressure build-up avoid rapid
evaporation (suffocation, elevator) do not breath
in use safety glasses use insulating gloves do
not work alone (as much as possible)
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Transport
only in metal vessels not at over-pressure careful
in the elevator only inert gases
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Liquid helium
Liquid helium Whenever one works with very low
temperatures, the safety aspect should play an
important roll. There are several hazards to
consider. 1. The fluids mentioned are extremely
cold as mentioned, helium is the coldest of all
fluids. Contact with cold fluids (even cold
helium gas!) causes severe frost burns. 2. The
extremely low temperatures of liquid helium will
cause air to condense and freeze. A typical
example of this is the occurrence of fluid
droplets on helium evaporation pipelines these
are droplets of liquid air, so be careful. 3.
When working with liquid helium, keep external
surfaces clean. In paragraph 2, the occurrence of
droplets on the outside of pipelines is
mentioned. In case of this kind of condensation,
the liquid nitrogen will evaporate out of the
liquefied air first, because it has a lower
boiling point than oxygen. As a result an
oxygen-rich fluid drips from the pipeline when
this happens, spontaneous ignition of grease and
oil is not impossible. A clean work area is
important. 4. NEITHER helium, NOR nitrogen
supports life. At high concentrations of helium
gas or nitrogen gas an imminent oxygen shortage
occurs. Although helium is not toxic, it may
cause breathing difficulties in poorly ventilated
rooms. High concentrations of helium gas can be
noticed by the effect on the vocal cords.
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Gasses at high pressure
high pressure cylinders - do not drop - use
with safety cap - fix to the wall -
transport on cart with chain - do not pump on
pressure reducer - always close the main valve
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What to do if
there is an accident phone reception
5678 someone gets severely frozen phone EHBO
through reception 5678 telephone number outside
working hours 4444 someone gets a frozen spot
treat like burning lots of running water
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How to obtain cryogenic liquids
Cryogenic Department (groundfloor) Hans van Kuijk
5941 Rob van Noort Wilfred van der
Geest http//www.physics.leidenuniv.nl/institute/
cryo/command.asp
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Demonstration
Lets go