Parr Instrument Series 4540 - Manual (Page 14)

4540 High Pressure Reactor System
P a r r I n s t r u m e n t C o m p a n y 14
Gas Connections
Gas connections are dependent on applications.
For general usage, use the pressure hose furnished
with the reactor. Screw the Type “A” coned pressure
fitting into the adapter attached to the gas inlet valve
and tighten the compression nut firmly. Do not use
any thread dope on the coned fitting.
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. With the inlet valve open and the
flow control valve on the gas tank closed, open the
main valve on the gas tank only about one-quarter
turn; then use the flow control valve or the valve
on a pressure regulator to control the flow of gas
into the vessel. After the desired pressure has been
reached, close the tank valves and the vessel inlet
valve and disconnect the hose at the vessel end.
Do Not Overfill the Vessel
Always watch the pressure gage closely when
admitting gas so as not to exceed the maximum
working 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 ca-
pacity of the cylinder. Too much liquid in the vessel
can lead to development of dangerous pressures if
sufficient 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
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 sampling
valve attached to the same adapter as the gas inlet
valve whenever the vessel is pressurized. Always
close the inlet valve before withdrawing 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 150ºC while
checking the apparatus for leaks and observing the
performance of the temperature controller
Note: The following steps are common to both head configurations.