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P a r r I n s t r u m e n t C o m p a n y
1 - 8 0 0 - 8 7 2 - 7 7 2 0
5
O p t i o n a l F i t t i n g s
External Valves and Fittings
powerful than external heat-
ers. Internally heated vessels
are equipped with insulated
electrical feed-throughs to
power the heater and multiple
thermocouples to monitor
and control the temperatures
in the hot zone and the vessel
inner wall.
The reactions or studies
carried out in internally heated
vessels must be limited to
those which will not destroy
the exposed internal heaters
and insulation. These are
normally gas-solid reactions
or controlled atmosphere
heat treatment studies. The
heating elements are normally
ceramic. Some users have
developed induction style
heaters and insulators and
have extended their investiga-
tions to above 2500 °C.
Although internal heaters
can be installed in almost
any non-stirred Parr pressure
vessel the 1.8 liter, Model
4683 High Pressure/High
Temperature vessel is an
excellent starting point. It can
accommodate a cylindrical,
insulated heater 1.75" diameter
by 8" deep, capable of produc-
ing and sustaining internal
temperatures to 1200 °C.
Protected Heaters.
Internally heated vessels
have also been manufactured
with cartridge type heating
elements inserted in specially
designed “thermowells”.
These wells protect the heater
from the reactants and expand
the applications that can be
studied. Cartridge type heaters
have a maximum temperature
of 760 °C.
Materials of Construction
I
n the standard configuration,
the valves, gage, magnetic
drive and other external parts
on Parr reactors are furnished
in stainless steel, even when a
different material is specified
for the cylinder, head and
internal wetted parts. The
external stainless components
are typically only exposed to
the vapor of the reactants and
are at much lower temperature
than the cylinder and internal
fittings. These conditions allow
stainless steel external fittings
to perform satisfactorily in
most cases. If external parts
made of a material other than
stainless steel are required for
safety or other reasons, Parr
can accommodate this in most
cases. Any request for external
parts made of a specific mate-
rial must be stated clearly
when ordering.
Valves
Most reactor valves are
available in Alloy 400 as well
as stainless steel at a reason-
able cost premium. Valves
made of Alloy C-276 are also
available, but generally only
on special designs and at a
considerable cost premium.
Soft materials such as titanium
and zirconium generally make
poor performing valves.
Gages
Pressure gages are avail-
able in Alloy 400 and stainless
steel. Other materials of
construction are not avail-
able. The standard method
for protecting the gage in a
corrosive environment is to
install a diaphragm gage pro-
tector. These have a flexible
diaphragm which isolates the
gage from the reactants and
a sealed hydraulic connection
for pressure transfer to the
gage. These assembles are too
large to install on all but the
largest Parr reactors.
As an alternative, Parr has
designed an oil filled piston
isolator gage protector to iso-
late the gage (and transducer,
if required) on small reactors
and pressure vessels where
space is limited. These isola-
tors can be furnished in any of
the current Parr materials of
construction.
Pressure Transducers
Pressure transducers are
only available in stainless
steel and Alloy C-276. Parr
provides a mounting adapter
with a water cooling jacket
on pressure transducers to
protect them from excessive
temperatures. These can be
augmented with piston style
isolators similar to gage
protectors when corrosion
resistance is required. When
a gage and a pressure trans-
ducer are installed, a single
isolator can protect both.
Magnetic Drives
Magnetic drives can be
furnished in all of the current
Parr materials of construc-
tion except nickel, which is
magnetic.
Rupture Discs
The standard material of
construction for rupture discs
is Alloy 600. A gold facing is
available for the smaller discs
used on vessels up through 2
liters in volume. Alloy C-276,
Tantalum and other premium
materials are available on
special order.
