Parr Instrument Series 4570 - Manual (Page 13)

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4570 HP/HT Pressure Reactors Parr Instrument Company
HOW TO USE THE VESSEL
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Continued )
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 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Liquid samples may be withdrawn from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 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
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 handling 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.