Parr Instrument Series 4580 - Manual (Page 15)

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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 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
Safety Instruction Manual No. 230M.