Parr Instrument Series 4530 - Manual (Page 11)

Floor Stand Reactors
w w w . p a r r i n s t . c o m 11
be used at ambient temperature for all non-corro-
sive gases at pressures up to 2500 psig. For opera-
tions involving corrosive gases, this hose should
be replaced with an A490HC hose which has a PTFE
lining and a braided stainless steel outer cover-
ing. Both of these hoses have the same fi ttings. The
A506HC all metal hose is also available in stainless
steel and other corrosion resistant materials.
Pressurizing the Vessel
Check all valves carefully before admitting gas into
the system. The liquid sampling valve must remain
closed throughout the charging procedure. The gas
release valve must also be closed unless the vessel
is to be purged, or unless there is to be a continu-
ous fl ow through the reactor during a run. Always
make certain that the pressure in the gas tank is
greater than the pressure in the vessel; otherwise
liquid will be forced out of the vessel and into the
gas tank when the inlet valve is opened. If there is
any possibility that the tank pressure might not be
high enough to force gas into the reactor, install
a one-way check valve (optional) in the gas line to
prevent any reverse fl ow. After the desired pressure
has been reached, close the valves and disconnect
the hose at the vessel end.
Alternate gas hoses with check valves are avalable
from Parr upon request.
Do Not Overfi ll the Vessel
Always watch the pressure gage closely when ad-
mitting gas so as not to exceed the maximum work-
ing limit. Remember that any subsequent increase
in temperature will raise the pressure. Also, be
sure that the amount of liquid placed in the vessel
is carefully controlled. As a general rule, the liquid
charge should not exceed two-thirds of the capac-
ity of the cylinder. Too much liquid in the vessel can
lead to development of dangerous pressures if suf-
fi cient space is not provided for expansion when the
liquid is heated. This hazard is explained in greater
detail in a warning statement included in the Safety
Instruction Manual No. 230M.
Releasing Pressure
Use the gas release valve to reduce the pressure in
the vessel if the reactor is accidentally overcharged
when fi lling. Use this valve also to release any ex-
cess pressure during a run and to exhaust the vessel
at the end of a run. If the discharge gases are fl am-
mable or toxic, discharge to an exhaust hood or to
any other safe release point.
Withdrawing Liquid Samples
Liquid samples may be withdrawn from the sam-
pling valve attached to the same adapter as the gas
inlet valve whenever the vessel is pressurized. Al-
ways close the inlet valve before withdrawing a liq-
uid sample and open the sampling valve cautiously
because liquid will be discharged with considerable
force. Be particularly careful if the temperature of
the sample is above its boiling point at atmospheric
pressure. If so, it will “fl ash” and be lost as soon
as it is released from the vessel. This problem can
be avoided by connecting an optional 4351 Sample
Collection Vessel to the sampling valve to collect the
liquid into an appropriate receiver. The addition of
a small amount of gas can be used to clear the dip
tube between liquid samples so that the next sam-
ple drawn through the tube will truly be representa-
tive of the mixture..
Initial Operating Test
Read all operating instructions carefully so as to be
well acquainted with the correct procedures for han-
dling the vessel and for operating the controller and
other accessories. An initial operating test should
be made, with only water, to check the apparatus
before starting the fi rst experimental runs. For this
initial test, fi ll the cylinder not more than half full
of water and run the temperature up to 150ºC while
checking the apparatus for leaks and observing the
performance of the temperature controller.