Parr Instrument Series 4550 - Manual (Page 15)

4550 Floor Stand Reactors
w w w . p a r r i n s t . c o m 15
be replaced with an A490HC hose which has a PTFE
lining and a braided stainless steel outer covering.
Both of these hoses have the same fittings. 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 continuous
flow 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 flow. 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 available
from Parr upon request.
Do Not Overfill 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 capacity
of the cylinder. Too much liquid in the vessel can
lead to development of dangerous pressures if suf-
ficient 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 filling. Use this valve also to release any
excess pressure during a run and to exhaust the
vessel at the end of a run. If the discharge gases are
flammable 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Liquid samples may be withdrawn from the sam-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.
Always close the inlet valve before withdraw-
ing a liquid 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 “flash” and be
lost as soon as it is released from the vessel. This
problem can be avoided by connecting an optional
4352 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 sample drawn through the tube will truly
be representative 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 first experimental runs. For this
initial test, fill the cylinder not more than half full of
water and run the temperature up to 150 ºC while
checking the apparatus for leaks and observing the
performance of the temperature controller.