Parr Instrument Series 5100 - Manual (Page 11)

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5100 Low Pressure Reactors
11
How to use the Vessel
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 fining. The A495HC
pressure hose is made of reinforced Nylon which
can be used for all noncorrosive gases at pressures
up to 2500 psig. For operations involving corrosive
gases, this hose should be replaced with an A490HC
hose which has a PTFE lining and a braided stain-
less steel outer covering. Both of these hoses have
the same fittings. An 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. 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 capacity 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 warn-
ing 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 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 “flash” 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 first experimental runs. For this
initial test, fill the cylinder not more than half full of
water and run the temperature up to 150 ° C while
checking the apparatus for leaks and observing the
performance of the reactor controller.