American Magnetics 185 & 186 Liquid Level Instruments (CE-Marked) - Manual (Page 9)

Rev. 3 ix
Foreword
Safety Summary
2. Do not apply heat. Loosen any clothing that may restrict
circulation. Apply a sterile protective dressing to the affected area.
3. If the skin is blistered or there is any chance that the eyes have
been affected, get the patient immediately to a physician for
treatment.
Containers of cryogenic liquids are self pressurizing (as the liquid boils off,
vapor pressure increases). Hoses or lines used to transfer these liquids
should never be sealed at both ends (i.e. by closing valves at both ends).
When pouring cryogenic liquids from one container to another, the
receiving container should be cooled gradually to prevent damage by
thermal shock. The liquid should be poured slowly to avoid spattering due
to rapid boil off. The receiving vessel should be vented during the transfer.
Introduction of a substance at or near room temperature into a cryogenic
liquid should be done with great caution. There may be a violent gas boil
off and a considerable amount of splashing as a result of this rapid boiling.
There is also a chance that the material may crack or catastrophically fail
due to forces caused by large differences in thermal contraction of different
regions of the material. Personnel engaged in this type of activity should
be instructed concerning this hazard and should always wear a full face
shield and protective clothing. If severe spraying or splashing could occur,
safety glasses or chemical goggles along with body length protective
aprons will provide additional protection.
The properties of many materials at extremely low temperatures may be
quite different from the properties that these same materials exhibit at
room temperatures. Exercise extreme care when handling materials cooled
to cryogenic temperatures until the properties of these materials under
these conditions are known.
Metals to be used for use in cryogenic equipment application must posses
sufficient physical properties at these low temperatures. Since ordinary
carbon steels, and to somewhat a lesser extent, alloy steels, lose much of
their ductility at low temperatures, they are considered unsatisfactory and
sometimes unsafe for these applications. The austinetic Ni-Cr alloys
exhibit good ductility at these low temperatures and the most widely used
is 18-8 stainless steel. Copper, Monel
®
, brass and aluminum are also
considered satisfactory materials for cryogenic service.
Safety Summary
Cryogenic storage systems are complex systems with the potential to
seriously injure personnel or equipment if not operated according to
procedures. Proper use of safety mechanisms (pressure relief valves,