[Beowulf] immersion cooling baths and US OSHA dip tank regulations

[Mark Kosmowski]

 As an industrial hygienist that used a personal Beowulf cluster
during graduate studies in chemistry, I found the recent discussion on
immersion cooling doubly interesting.  Is an immersion coolant bath a
dip tank according to US OSHA regulations?  The two potentially
relevant ways for such use to be considered a dip tank would be if the
immersion bath is considered to either "alter the surface of an
object" or "change the character of an object".  Ultimately, it would
be up to the OSHA Inspector and associated legal team to decide
whether they wanted to pursue temperature change as meeting one of
these criteria.

If it is determined that an immersion bath is a dip tank, then there
are some specific requirements for liquids with a flashpoint.  All
liquids with a flashpoint of less than 200 F are covered by these
requirements, liquids with a flashpoint greater than 200 F are covered
by these special requirements (OSHA Standard 1910.125) if "the liquid
is heated as part of the operation".  So, pretty much any liquid used
as an immersion coolant that has a flashpoint would be covered, as the
whole purpose of the setup is to heat the liquid (and then
subsequently cool it).

The major elements of this specific standard is that a fire
suppression system or a lid that can be operated manually and that
automatically closes in the event of a fire be installed if the tank
contains more than 150 gallons of flammable liquids (remember, OSHA
considers any liquid with a flashpoint to be a flammable liquid now)
or has a liquid surface area of more than 4 square feet.  The other
element of concern is that a liquid with a flashpoint used in a dip
tank may not be heated to the boiling point (regardless of the size of
the dip tank).  Do the phase change liquids have flashpoints?  There
are some other regulations involving overflow piping and drainage
dependent on the size of the dip tank.

Happy, and safe, computing!