Parr Instrument Series 3900 - Manual (Page 8)

Hydrogenation Apparatus
P a r r I n s t r u m e n t C o m p a n y 8
Pressure Limits
The use of glass bottles in these reactors introduces
certain pressure limitations and a potential hazard
which the user must understand. Although each
bottle is pressure tested before it is sold, the physi-
cal characteristics of glass are such that it is impos-
sible to guarantee these bottles against breakage
or to predict their service life. For this reason, each
apparatus is equipped with a bottle shield to restrain
fl ying glass in case of breakage. The user must take
whatever additional precautions he considers neces-
sary to protect himself from injury in case a bottle
should unexpectedly fail. Working pressures should
never exceed 60 psig when using either 250 or 500
mL bottles in the 3911 apparatus, and never more
than 40 psi for one liter bottle and 30 psi for two liter
bottle in the 3921 apparatus.
Safety Barricades
Parr shaker type hydrogenators are usually operated
in an open laboratory without additional barricades
or protective screens, but the operator must realize
that additional protection may be necessary if there
is any possibility that a reaction might run out of
control, or if unexpected bottle breakage would pro-
duce a hazardous spill of toxic or fl ammable materi-
als. Potentially explosive reactions are best handled
with the apparatus located behind a suitable barri-
cade or in a pressure test cell.
If a barricade is used it should be built of concrete,
brick or steel in whatever thickness or form is con-
sidered necessary to protect the operator from fl y-
ing fragments if the reaction bottle should explode.
Glass shields, either plain or reinforced with wire
mesh, are not recommended. The requirements
for barricades differ so widely that each should be
designed and built in order to protect against the
potential hazards inherent in each installation. This
subject is well covered in the references listed on
page 15.
General Precautions
Pressure reactions with hydrogen are not unduly
hazardous if the user maintains his hydrogenator in
good condition and operates it with the realization
that hydrogen is highly fl ammable and that pres-
sures and reaction rates must be carefully controlled
at all times.
All catalysts must be handled cautiously because of
their highly reactive nature. Do not add dry catalyst
to a bottle containing a fl ammable solution or vapor.
The vapor might ignite. Instead, add the catalyst
fi rst and cover it immediately with the sample in
solution. Precautions must also be taken to wash the
catalyst from the thermocouple, the inlet tube and
the stopper when opening the bottle. Any catalyst
left on these parts may ignite when exposed to the
Gas Tank and Valve System